Self-lofting devices propelled by sunlight have been tested for the first time in near-vacuum conditions akin to those in Earth's upper atmosphere, paving the way for a revolution in atmospheric science.

The tiny, lightweight membranes — which are made of aluminum oxide and a layer of chromium — take advantage of a phenomenon known as photophoresis, which occurs when one side of a slice of thin material gets warmer than the other. As gas molecules bounce off the warmer side, they push the membrane upward. However, the effect is very weak and thus can be observed only in very low-pressure environments, such as those near the edge of space.

In the recent experiment, described in a paper published Aug. 13 in the journal Nature, the researchers made 0.4-inch-wide (1 centimeter) specks float in a vacuum chamber when exposed to light about 55% as intense as natural sunlight.

"That's a big result showing that this would actually work in the same conditions that you have in the upper atmosphere," said Ben Schafer, lead author of the paper and a researcher at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS).

"We are talking [about a] region of the atmosphere that is sometimes called the ignorosphere, because there is nothing that can fly there. Being able to send something out there would enable us to take a lot more precise data than we currently can," he told Space.com.

Related: Earth's elusive 'ignorosphere' could shed new light on auroras

The ignorosphere includes the mesosphere — the layer of Earth's atmosphere at altitudes between 30 and 53 miles (50 to 85 kilometers) — plus a section of the thermosphere up to an altitude of 100 miles (160 km). The ignorosphere is too high for aircraft to reach but too low for instruments on board low-Earth-orbit satellites to sample. Sensors placed on sounding rockets make occasional measurements of the region, but most of the processes taking place there are little understood.

The ignorosphere forms a boundary between Earth's gaseous shroud and outer space. When coronal mass ejections — vast expulsions of charged plasma from the sun — hit Earth, they deposit most of their energy in the ignorosphere. Auroral glows occur in the ignorosphere, and so do the energetic exchanges that lead to geomagnetic storms that can knock out power grids and throw satellites off their orbits. These unexplored altitudes are also where satellites burn up during their reentries and where the air pollution produced during their incineration accumulates.

"Getting accurate data from this region about winds, temperatures, pressures, etc. would really up the accuracy of existing global climate models," Schafer said. "It would fill that gap that we have."

Shafer and his colleague Angela Feldhaus spun out a company from Harvard SEAS called Rarefied Technologies. The aim of the startup is to conduct realistic atmospheric experiments with such devices in the hope of commercializing them.

To lift miniature sensors and antennae into the ignorosphere, the membranes would have to be somewhat bigger, around 2.4 inches (6 cm) wide. "It would be a disc that could loft about 10 milligrams [0.0004 ounce] into near space," Schafer said.

The devices would be released from a stratospheric balloon about 30 miles (50 km) above Earth. From there, they would self-propel to altitudes of up to 60 miles (100 km), where they would remain during the day. At night, the devices would sink down in the atmosphere, but if they were lightweight enough, wouldn't fall all the way back to Earth and would rise back up after sunrise, Schafer explained.

The researchers want to focus on improving the material and its structure to decrease its weight, which would make larger devices possible.

Building on earlier ideas

Photophoresis was discovered in the 19th century but remained mostly overlooked until recently. Advances in material science and nanofabrication technology in the past couple of decades finally made it possible to contemplate its practical applications.

Schafer and his colleagues got inspired by a theoretical paper by David Keith, then a professor of applied physics at SEAS and now at the University of Chicago. Keith proposed that reflective membranes powered by photophoresis could be used as a geoengineering intervention to reduce Earth's temperature if the world failed to contain climate change by reducing its carbon emissions.

Keith oversaw Schafer's work until 2023.

"This is the first time anyone has shown that you can build larger photophoretic structures and actually make them fly in the atmosphere," Keith said in a statement. "It opens up an entirely new class of device: one that's passive, sunlight-powered, and uniquely suited to explore our upper atmosphere."

Schafer thinks the technology could find many uses. It could help study Mars' thin atmosphere or even compete with SpaceX's Starlink satellite broadband megaconstellations.

"If you were to put small communications packages on board of these things and lofted them into the mesosphere, you could actually rival data rates of low-Earth-orbit constellations," Schafer said.

He admitted that the devices would have to get quite a bit lighter and larger to host large-enough communication payloads and navigation units to maintain a stable position above fixed spots on Earth.

Researchers from Kyushu University in Japan have provided some new insights about the powerful geomagnetic storm that flared up last Mother's Day, after a big solar storm hit Earth.

The work focuses on the storm's activity in a region of Earth's ionosphere called the E layer, which sits in the upper atmosphere about 56 miles to 75 miles (90 to 120 kilometers) above sea level.

"The sporadic E layer hasn't been studied very much during the storm because it appeared unaffected by solar storms," study leader Huixin Liu said in a statement.

"But we wanted to see if something as powerful as the Mother's Day geomagnetic storm did anything to the E layer," Liu added. "What we found was very interesting."

The E layer was significantly enhanced during the storm, the team found; thin patches of high ionization density — known as sporadic E layers, or sporadic Es for short — suddenly appeared in the ionosphere.

To gather data on the phenomena, the team relied on a combination of sources from space and on the ground.

Using the joint U.S.-Taiwanese COSMIC-2 satellite network, as well as 37 ground-based radars called ionosodes, the team gathered a massive amount of information during and after the solar storm to get a global map of sporadic E layer activity.

Related: The US isn't prepared for a big solar storm, exercise finds

"This large amount of data was critical for both detecting the presence of sporadic Es and tracking where they formed as time went by," Liu said.

"In our analysis, we found that sporadic Es formed after the main phase of the solar storm, during what we call the recovery phase," Liu added.

First, the team detected sporadic Es at higher latitudes, around the poles. The phenomena slowly extended toward the equator over time. "This propagation characteristic from high to low latitudes suggests that sporadic E layers are most likely caused by the disturbed neutral winds in the E region," Liu said.

The researchers want to understand this phenomena because it can disrupt HF (high frequency) and VHF (very high frequency) bands of radio communication, which have important uses in areas such as navigation.

With greater insight into activity in the E layer during a geomagnetic storm, the researchers hope to find ways to work around the disruptions.

The new paper was published last month in the journal Geophysical Research Letters.

This article was originally published on Space.com.

The rapid unscheduled disassembly (aka explosion) of SpaceX's Starship megarocket that rained scorching fragments of metal across the Caribbean in mid-January may have released significant amounts of harmful air-pollution into the upper layers of Earth's atmosphere.

The rocket's upper stage blew up at an altitude of around 90 miles (146 kilometers) according to astronomer and space debris expert Jonathan McDowell, and weighed some 85 tons without propellant. Its plunge back to Earth through the atmosphere may have generated 45.5 metric tons of metal oxides and 40 metric tons of nitrogen oxides, according to University College London atmospheric chemistry researcher Connor Barker. Nitrogen oxides in particular are known for their potential to damage Earth's protective ozone layer.

Barker, who had recently published an inventory of rocket emissions and pollutants from satellite re-entries in the journal Nature, posted the estimates on his LinkedIn profile shortly after the mishap. He, however, stressed in an email to Space.com that the numbers are a rough, preliminary estimate rather than an accurate calculation of the accident's environmental impact.

In Barker's LinkedIn post, however, the scientist said that the amount of metallic air pollution potentially produced in the accident equals that generated by one third of meteorite material that burns up in Earth's atmosphere every year.

Exactly how much pollution the Starship mishap produced in the higher atmosphere is hard to tell. Scientists, for example, are also not sure how much of the megarocket's mass burned up and how much of it fell to Earth.

Related: ISS dodges its 39th piece of potentially hazardous space junk. Experts say it won't be the last.

McDowell told Space.com that "many tons" likely splashed down into the ocean.

Fortunately, the Starship upper stage is made of stainless steel and not aluminum like satellites and upper stages of many other rockets including SpaceX's Falcon 9. The incineration of aluminum is what worries many scientists. When aluminum burns at high temperatures during a satellite re-entry, it produces aluminum oxides, or alumina, a white powdery substance known for its potential to damage ozone and change the reflectiveness of Earth's atmosphere.

In recent years, the number of satellites orbiting Earth and that of subsequent atmospheric re-entries has been rising fast. With that the amount of alumina released into the mesosphere and upper stratosphere — the otherwise pristine middle layers of the atmosphere — has been skyrocketing. Air pollution in the mesosphere and upper stratosphere concerns scientists as the high altitudes at which it arises mean the pollutants remain in the air for a very long time.

Scientists think that the quantity of alumina from incinerated satellites is already approaching the same levels that result from the atmospheric demise of natural space rocks such as asteroids or meteoroids, which contain only trace amounts of aluminum. The amount of nitrogen oxides produced during re-entries is also nearing that generated by natural space rocks.

Nitrogen oxides arise as space rocks or space debris fragments, travelling at hyper-sonic speeds, compress the surrounding air as they fall to Earth. The atoms of nitrogen heat up and react with oxygen, creating the harmful oxides.

With the expected increase in rocket launches and the growth of satellite fleets and the subsequent frequency of re-entries, concentrations of these damaging gases and particles could quickly rise. The pollutants could thwart the recovery of the planet's ozone layer, worsening the damage caused by ozone-depleting substances used in aerosol sprays and refrigerators in the past. The air pollution from incinerated satellites could also change how much heat the Earth's atmosphere retains, leading to possibly serious consequences on the planet's climate.

Originally posted on Space.com.

Japanese scientists have created the first-ever long-term dataset about Earth's entire atmosphere, stretching all the way to space.

They hope the project will help shed light on some little-explored processes taking place inside our planet's gaseous shroud, including the magnificent northern lights.

Some parts of Earth's atmosphere are studied continuously in incredible detail. For example, millions of weather stations all around the world, hundreds of meteorological balloons and countless airplanes provide daily measurements of the entire troposphere, the atmosphere's lowest region. The balloons also reach the lower part of the stratosphere, the layer above the troposphere. The amount of data generated by these measurements is so high that it makes modern computational weather models nearly infallible.

Look a little higher, however, and the story is completely different. The mesosphere, the layer of sparse air above the stratosphere that reaches nearly to the edge of space, is very much a complete unknown. So little is known about processes in the mesosphere that the region is sometimes called the "ignorosphere." This void in our knowledge is a result of the ignorosphere's unreachability — it's too high for stratospheric balloons and generally too low for instruments on satellites in low Earth orbit to explore.

Related: Extremely rare, black 'anti-auroras' paint luminous 'letter E' above Alaska

A team of researchers from the University of Tokyo attempted to solve the problem using computer modelling. They took the rare available measurements of meteorological parameters in the ignorosphere — obtained by sounding rockets and Earth-based radar and lidar instruments — and fed them into a new data assimilation system they had developed earlier. Data assimilation is a technique that combines modelling with direct observations to predict the evolution of a system. The system was then instructed to reconstruct what may be happening within the mesosphere to fill in the blanks.

The Japanese researchers used the model to generate 19 years' worth of data encompassing the evolution of the entire atmosphere up to the altitude of 110 kilometers (68.4 miles). They then used additional measurements of mesospheric winds obtained by ground-based radar to verify some parameters in the model to gain confidence in its results.

The dataset covers the period between September 2004 and December 2023 and will enable researchers to explore and model some of the mysterious phenomena that take place at higher altitudes, including the mesmerizing aurora borealis and its antipodean counterpart, the aurora australis.

"For the troposphere and stratosphere, we have a lot of data, and numerical modelling for this region is almost perfect," Kaoru Sato, a professor of atmospheric physics at the University of Tokyo and lead researcher behind the project, told Space.com. "In the region above, the models don't perform that well because they don't have accurate data of the initial conditions. Our dataset can provide that."

The ignorosphere is the atmospheric region where many effects related to space weather occur. When bursts of charged particles from the sun hit our planet, they mix with the thin gases high above Earth, exciting the air molecules. As that happens, the molecules give off the mesmerizing glow we can observe on Earth as the auroras. But there are other, less visible effects that space weather has on the atmosphere.

"The high-energy solar particles can change ozone chemistry and disrupt the ozone layer," Sato said. "We also know that the aurora phenomenon can create what we call gravity waves, which then propagate downward into the atmosphere."

Gravity waves (not to be mistaken for the gravitational waves produced by black hole collisions, among other dramatic encounters) are vortices that occur throughout the atmosphere. They transport energy across the globe, thus affecting climate patterns. So far, however, climate modelers haven't been able to understand the effects of gravity waves that occur at higher altitudes.

"Our dataset provides initial conditions in very high resolution for the general circulation model of the atmosphere," Sato said. "So, it allows us to simulate gravity waves in the entire atmosphere, from the surface to the edge of space."

The data will also help researchers better model how processes in the lower atmosphere affect the ionosphere, the part of the atmosphere above altitudes of 50 miles (80 km), where gaseous particles are constantly ionized by the solar wind. Sato said that atmospheric waves, including gravity waves and global-scale tidal waves, affect the ionospheric dynamo, a process generating an electrical current around the planet through the interaction between Earth's magnetic field lines and the motions of the ionized air of the ionosphere.

There are other mysteries the researchers hope their dataset will help to crack — for example, the odd phenomenon known as inter-hemispheric coupling, first observed in the late 2000s. The inter-hemispheric coupling is an assumed connection between the Antarctic mesosphere and Arctic stratosphere, in which rare high-altitude clouds regularly appear and disappear at the same time, usually in the month of January, Sato said.

"If we want to understand the mechanisms behind this inter-hemispheric coupling, we need data," said Sato. "Our dataset can provide very valuable information to tackle this coupling."

A paper describing the work done by the Japanese team was published in the journal Progress in Earth and Planetary Science on Jan. 10.

Originally posted on Space.com.

A loud boom that shattered the Saturday morning quiet in Utah may have been a Perseid meteor. 

According to The Deseret News, the noise startled northern Utah at about 8:32 a.m. local time. Numerous home security and doorbell cams caught the sound. Seismographs ruled out an earthquake, and the National Weather Service Salt Lake City soon posted a radar image of two red flashes on a lightning monitor — in a spot where there was neither lightning nor a storm. The flashes were likely the meteor trail and flash, according to the weather service. 

Home security camera footage from Roy, Utah, soon clinched the identification: Posted to Twitter, the video shows a blue fireball streaking across the morning sky just before the boom.

Numerous reports of the fireball were posted to the American Meteor Society. 

Related: What’s the difference between asteroids, comets and meteors?

There have been no reports of meteorites found from the explosion, though a NASA volunteer told KSLTV that the explosion may have scattered space rock fragments across the area. The destruction of the meteor makes it hard to determine where it originated from, but a likely culprit is the Perseids, experts told the Deseret News. 

The Perseid meteor shower occurs each year in July and August as Earth swings through debris left by the comet 109P/Swift-Tuttle. Most of this debris is miniscule, but it hits Earth's atmosphere at 133,200 mph (214,360 km/h), according to the American Meteor Society. This year, the Perseids peaked on Aug. 11 and 12. 

Meteors create sonic booms when they move across the atmosphere faster than the speed of sound, according to CalTech's CoolCosmos. Because light moves faster than sound, the "boom" of a traveling meteor usually comes several seconds after the sight of the fireball. But in most cases, meteors are too high in the atmosphere for the sound to reach any listening ears on the ground. 

Falling space rock is relatively common. Earlier this year, a fireball lit up the skies over Ontario, Canada. Another scattered small meteorites (space rocks that reach the ground) over Mississippi. On rare occasions, meteors large enough to cause damage streak through the atmosphere. In 2013, a large fireball exploded over Chelyabinsk, Russia, blowing out thousands of windows and creating an eye-burning flash. The meteor that caused the fireball was an estimated 65 feet (20 meters) across, according to EarthSky. 

Originally published on Live Science.

Look up at the sky on a clear night in a dark area, and the stars appear to twinkle. The concept is so well established that it's the premise of one of the most popular children's songs of all time. 

But what's the science behind this sparkly sight? What is it about stars that makes them twinkle?

It turns out, "twinkle, twinkle, little star" is a bit of a misnomer.

Related: 15 unforgettable images of stars

Stars don't actually twinkle

The honest answer to why stars twinkle is that they don't. The twinkling we see has nothing to do with the stars themselves. Rather, it's a result of how we see them from our perspective on Earth.

Because stars are so far away, we see them as tiny points of light in the night sky.

"Starlight travels a great distance to reach our eyes on a clear night," said Ryan French, a solar physicist at University College London in the U.K. After our own star, the sun — whose average distance to Earth is 93 million miles (150 million kilometers) — the nearest star to us isProxima Centauri, which is over 4 light-years from Earth.

On the way to our eyes, this light from distant stars encounters Earth's atmosphere — the key driver behind the twinkling effect.

"As this point of light reaches the atmosphere, it passes through layers of wobbling air before reaching our eyes, causing it to twinkle," French said. 

So it's Earth's wobbling atmosphere that makes stars appear to twinkle. In space, high above the atmosphere, stars don't twinkle at all. (That's one reason why the Hubble Space Telescope was sent into orbit: It could get sharper images of space without the images being distorted by atmospheric turbulence.)

Why some stars twinkle more than others

Many factors affect how much a star appears to twinkle. One variable is the star's place within our field of view.

"Stars will twinkle more if their starlight travels through more air before reaching our eyes," French said, so stars near the horizon appear to twinkle more because their light has to  journey through more atmosphere to get to us. 

Weather also plays a role. "Humid nights will also cause the air to be thicker," making stars appear to twinkle more, French said. 

These issues help guide astronomers when they are deciding where to place the world's biggest and best telescopes. "Observatories are placed in high, dry places, to remove as much air between the star and telescope as possible," French said. 

Ideal spots include the bone-dry Atacama Desert in Chile, as well as the volcanic peaks of Hawaii and the Spanish Canary Islands. These locations are examples of places with what astronomers refer to as good "seeing." "Thick air, causing a lot of wobble or twinkle, is bad seeing, whereas dry, calm and thin air creates good seeing."

When you look up at the night sky, you may also notice that some stars appear to shift between different colors as they twinkle. Sirius, the brightest star in Earth's night sky, is a classic example. 

"Starlight gets refracted [bent] by the atmosphere a little bit, which can cause it to change color," French said. This effect is more noticeable with brighter stars.

You may also notice a few "stars" that don't twinkle at all. That's because they are actually planets. "Unlike stars, planets are not point sources in the sky, but have width," French said. "This is because they are far closer to us." In other words, they are too big in the night sky for the atmosphere to make them appear to twinkle.

However, if you look at the planets, or even the moon, through a telescope, you'll still see them appear to shimmer, as the light you're seeing has been jostled by the atmosphere on its way to your eyes.

Original article on Live Science.

Millions of tons of a class of extremely reactive chemicals called hydrotrioxides can linger in the atmosphere for several hours, a new study suggests  — which could have implications for human health and the global climate.

The chemicals interact with other compounds extremely quickly, and their presence means that chemists will have to rethink just how processes in the atmosphere occur.

It's long been thought that hydrotrioxides — chemical compounds that contain a hydrogen atom and three oxygen atoms — were too unstable to last long under atmospheric conditions.

But the new research shows instead that hydrotrioxides are a regular product of many common chemical reactions, and that they can stay stable enough to react with other compounds in the atmosphere.

"We showed that the lifetime of one of them was at least 20 minutes," Henrik Grum Kjærgaard, a chemist at the University of Copenhagen, told Live Science. "So that's long enough for them to do stuff in the atmosphere."

Related: 10 signs that Earth's climate is off the rails

Kjærgaard is one of the authors of a new study on hydrotrioxide formation in the atmosphere published online May 26 in the journal Science.

The discovery doesn't mean that something new is happening in the atmosphere; rather, it seems that hydrotrioxides have always formed there. But the new study is the first time that the existence of these ultra-reactive chemicals in the atmosphere has been verified. 

"We can now show, through direct observation, that these compounds actually form in the atmosphere, that they are surprisingly stable and that they are formed from almost all chemical compounds," University of Copenhagen doctoral student Jing Chen, the second author of the study, said in a statement. "All speculation must now be put to rest."

Powerful oxidants

Hydrotrioxides are a type of hydrogen polyoxide. Water is the simplest and most common hydrogen polyoxide, with two hydrogen atoms and one oxygen atom, or H2O. 

Another hydrogen polyoxide is hydrogen peroxide, which has two oxygen atoms — H2O2 — and is commonly used as a bleach or disinfectant. The extra oxygen atom also makes many peroxides extremely flammable, and they are sometimes used as a component of rocket fuels. 

Related: Why does Earth have an atmosphere?

Hydrotrioxides are a stage further, as they have three oxygen atoms attached to each other, which makes them even more reactive than peroxides. They're written chemically as ROOOH, where R is any bonded group, such as a carbon group.

But while it's known that peroxides can form  from chemical reactions in the atmosphere, it wasn't known before now that hydrotrioxides can also form there, albeit for a relatively short time before they decompose into less reactive chemicals.

In the new study, the researchers estimate that about 11 million tons (10 million metric tons) of hydrotrioxides form in the atmosphere each year as a product of one of the most common reactions: the oxidation of isoprene, a substance produced by many plants and animals and which is the main component of natural rubber. 

The researchers estimate around 1% of isoprene released into the atmosphere forms hydrotrioxides, and that they are produced from these reactions in very low concentrations — about 10 million hydrotrioxide molecules in a cubic centimeter of the atmosphere, which is only a very faint trace.

"We are super-happy that we were able to show that [hydrotrioxides] are there and that they are living long enough to be — most likely — important in the atmosphere," study lead author Torsten Berndt, an atmospheric chemist at the Leibniz Institute for Tropospheric Research (TROPOS) in Leipzig, Germany, told Live Science in an email. 

Atmospheric experiments

Berndt led the research laboratory experiments at TROPOS to discover if hydrotrioxides were in fact produced by chemical reactions in the atmosphere, while the University of Copenhagen team studied the theoretical aspects of how hydrotrioxides form.

Berndt and his colleagues used very sensitive mass spectrometry to detect the ultra-reactive hydrotrioxides — a technique that can determine the molecular weight of chemicals to find out what atoms they consist of. 

The reactions to make the hydrotrioxides took place in the TROPOS free-jet flow system, which creates a flow of air unobstructed by solid boundaries.

And the study also used the results of experiments in an atmospheric chamber at the California Institute of Technology at Pasadena.

Now that their research has confirmed that hydrotrioxides are formed by common chemical reactions in the atmosphere, the scientists will next investigate how the compounds might affect humanhealth and the environment during the minutes or hours of activity before the compounds decompose, Berndt said.

"From the knowledge of organic chemistry, we can expect that [hydrotrioxides] will act as an oxidant in the atmosphere," he said.  It’s also possible that hydotrioxides could have an effect when our lungs breathe in  air that contains them in very low concentrations, “but this is all very speculative at the moment."

Berndt said hydrotrioxides could also penetrate atmospheric aerosols — very fine solid particles or liquid droplets suspended in the atmosphere, such as the ash from volcanic eruptions or the soot from large fires — and they might initiate chemical reactions there. But "experimental investigations on that are very challenging," he said. "It's a lot to do."

Originally published on Live Science.

When mountaineers climb Mount Everest, they routinely carry oxygen cylinders, devices that allow them to breathe freely at high altitudes. This is necessary because the closer you get to the edge of Earth's atmosphere, the less oxygen there is available compared with the plentiful amounts found at sea level.

This is just one example of how variable Earth's atmosphere is and showcases the elemental makeup of its layers, from the troposphere, near sea level, to the exosphere, in its outermost regions. Where each layer ends and begins is defined by four key traits, according to the National Weather Service: temperature change, chemical composition, density and the movement of the gases within it. 

So, with this in mind, where does Earth's atmosphere actually end? And where does space begin?

Related: How much water is in Earth's atmosphere?

Each of the atmosphere's layers plays a role in ensuring our planet can host all manner of life, doing everything from blocking cancer-causing cosmic radiation to creating the pressure required to produce water, according to NASA.

"As you get farther from Earth, the atmosphere becomes less dense," Katrina Bossert, a space physicist at Arizona State University, told Live Science in an email. "The composition also changes, and lighter atoms and molecules begin to dominate, while heavy molecules remain closer to the Earth's surface."

As you move up in the atmosphere, the pressure, or the weight of the atmosphere above you, weakens rapidly. Even though commercial planes have pressurized cabins, rapid changes in altitude can affect the slim eustachian tubes connecting the ear with the nose and throat. "This is why your ears may pop during takeoff in an airplane," said Matthew Igel, an adjunct professor of atmospheric science at the University of California, Davis.

Eventually, the air becomes too thin for conventional aircraft to fly at all, with such craft not able to generate enough lift. This is the area scientists have decreed marks our atmosphere's end, and space's beginning.

It's known as the Kármán line, named after Theodore von Kármán, a Hungarian American physicist who, in 1957, became the first person to attempt to define the boundary between Earth and outer space, according to EarthSky.

This line, given it marks the boundary between Earth and space, not only denotes where an aircraft's limits lie, but is also crucial for scientists and engineers when figuring out how to keep spacecraft and satellites orbiting Earth successfully. "The Kármán line is an approximate region that denotes the altitude above which satellites will be able to orbit the Earth without burning up or falling out of orbit before circling Earth at least once," Bossert said. 

"It is typically defined as 100 kilometers [62 miles] above Earth," Igel added. "It is possible for something to orbit the Earth at altitudes below the Kármán line, but it would require extremely high orbital velocity, which would be hard to maintain due to friction. But nothing forbids it.  

"Therein lies the sense one should have for the Kármán line: It is an imaginary but practical threshold between air travel and space travel," he said. 

Various factors, such as the satellite's size and shape, play a part in determining how much air resistance it will experience and, consequently, its ability to orbit Earth successfully, according to Bossert. Typically, satellites that are in low Earth orbit — a classification that tends to be given to satellites at an altitude of less than 621 miles (1,000 km) but sometimes as low as 99 miles (160 km) above Earth, according to the European Space Agency — will fall out of orbit after a few years, Bossert said, due to "drag from the Earth's upper atmosphere gradually slowing down orbital speed." 

Related: How fast does the Earth move?

However, that doesn't mean Earth's atmosphere is undetectable beyond 621 miles.

"The atmosphere doesn't just disappear once you get into the region where satellites orbit," Bossert said. "It is thousands and thousands of kilometers away before evidence of Earth's atmosphere is gone. The very outer atoms from Earth's atmosphere, the hydrogen atoms that make up its geocorona [the outermost region of the atmosphere], can even extend beyond the moon."  

So, if someone were to reach the Kármán line, would they notice anything? Would they be aware that they were, essentially, straddling the boundary between Earth and space? Not really. "Nothing really changes," Bossert said.

Igel agreed. "The line is not physical, per se, and so one would not notice crossing it, nor does it have any thickness," he said.

What about being able to survive, even for a brief period, at the Kármán line? What if you were dropped there without a bespoke spacesuit or a mountaineering style oxygen tank? If you could get to it, would you be able to breathe at such a high altitude? And could birds ever reach such heights?

"In principle, flight is still possible all the way up to the Kármán line," Igel said. "In practice, however, animals cannot survive at altitudes above the 'Armstrong limit,' which is around 20 km [12 miles] above the surface, where pressures are so low that liquid in the lungs boils."

Originally published on Live Science.

Earth's transition to permanently hosting an oxygenated atmosphere was a halting process that took 100 million years longer than previously believed, according to a new study.

When Earth first formed 4.5 billion years ago, the atmosphere contained almost no oxygen. But 2.43 billion years ago, something happened: Oxygen levels started rising, then falling, accompanied by massive changes in climate, including several glaciations that may have covered the entire globe in ice. 

Chemical signatures locked in rocks that formed during this era had suggested that by 2.32 billion years ago, oxygen was a permanent feature of the planet's atmosphere.

But a new study delving into the period after 2.32 billion years ago finds that oxygen levels were still yo-yoing back and forth until 2.22 billion years ago, when the planet finally reached a permanent tipping point. This new research, published in the journal Nature on March 29, extends the duration of what scientists call the Great Oxidation Event by 100 million years. It also may confirm the link between oxygenation and massive climate swings.

Related: 10 times Earth revealed its weirdness

"We only now start to see the complexity of this event," said study co-author Andrey Bekker, a geologist at the University of California, Riverside.

Establishing oxygen

The oxygen created in the Great Oxidation Event was made by marine cyanobacteria, a type of bacteria that produces energy via photosynthesis. The main byproduct of photosynthesis is oxygen, and early cyanobacteria eventually churned out enough oxygen to remake the face of the planet forever.

The signature of this change is visible in marine sedimentary rocks. In an oxygen-free atmosphere, these rocks contain certain kinds of sulfur isotopes. (Isotopes are elements with varying numbers of neutrons in their nuclei.) When oxygen spikes, these sulfur isotopes disappear because the chemical reactions that create it don't occur in the presence of oxygen.

Bekker and his colleagues have long studied the appearance and disappearance of these sulfur isotope signals. They and other researchers had noticed that the rise and fall of oxygen in the atmosphere seemed to track with three global glaciations that occurred between 2.5 billion and 2.2 billion years ago. But strangely, the fourth and final glaciation in that period hadn't been linked to swings in atmospheric oxygen levels.

The researchers were puzzled, Bekker told Live Science. "Why do we have four glacial events, and three of them can be linked and explained through variations of atmospheric oxygen, but the fourth of them stands independent?"

To find out, the researchers studied younger rocks from South Africa. These marine rocks cover the later part of the Great Oxidation Event, from the aftermath of the third glaciation up to about 2.2 billion years ago.

They found that after the third glaciation event the atmosphere was oxygen-free at first, then oxygen rose and dropped again. Oxygen rose again 2.32 billion years ago — the point at which scientists previously thought the rise was permanent. But in the younger rocks, Bekker and his colleagues again detected a drop in oxygen levels. This drop coincided with the final glaciation, the one that hadn't previously been linked to atmospheric changes.

"Atmospheric oxygen during this early time was very unstable and it went up to relatively high levels and it fell down to very low levels," Bekker said. "That's something we didn't expect until maybe the last 4 or 5 years [of research]."

Cyanobacteria vs. volcanoes

Researchers are still working out what caused all these fluctuations, but they have some ideas. One key factor is methane, a greenhouse gas that's more efficient at trapping heat than carbon dioxide.

Today, methane plays a small role in global warming compared with carbon dioxide, because methane reacts with oxygen and disappears from the atmosphere within about a decade, whereascarbon dioxide sticks around for hundreds of years. But when there was little to no oxygen in the atmosphere, methane lasted a lot longer and acted as a more important greenhouse gas.  

So the sequence of oxygenation and climate change possibly went something like this: Cyanobacteria began producing oxygen, which reacted with the methane in the atmosphere at the time, leaving only carbon dioxide behind. This carbon dioxide wasn't abundant enough to make up for the warming effect of the lost methane, so the planet started to cool. The glaciers expanded, and the surface of the planet became icy and cold. 

Saving the planet from a permanent deep-freeze, though, were subglacial volcanoes. Volcanic activity eventually boosted carbon dioxide levels high enough to warm the planet again. And while oxygen production lagged in the ice-covered oceans due to the cyanobacteria receiving less sunlight, methane from volcanoes and microorganisms again began to build up in the atmosphere, further heating things up. 

But volcanic carbon dioxide levels had another major effect. When carbon dioxide reacts with rainwater, it forms carbonic acid, which dissolves rocks more quickly than pH-neutral rainwater. This faster weathering of rocks brings more nutrients such as phosphorus into the oceans. More than 2 billion years ago, such a nutrient influx would have driven the oxygen-producing marine cyanobacteria into a productive frenzy, again boosting atmospheric oxygen levels, driving down methane and starting the whole cycle again.

Eventually, another geological change broke this oxygenation-glaciation cycle. The pattern seems to have ended about 2.2 billion years ago when the rock record indicates an increase in organic carbon being buried, which suggests that photosynthetic organisms were having a heyday. No one knows exactly what triggered this tipping point, though Bekker and his colleagues hypothesize that volcanic activity in this period provided a new influx of nutrients to the oceans, finally giving cyanobacteria everything they needed to thrive. At this point, Bekker said, oxygen levels were high enough to permanently suppress methane's oversized influence on the climate, and carbon dioxide from volcanic activity and other sources became the dominant greenhouse gas for keeping the planet warm.

There are many other rock sequences from this era around the world, Bekker said, including in western Africa, North America, Brazil, Russia and Ukraine. These ancient rocks need more study to reveal how the early cycles of oxygenation worked, he said, particularly to understand how the ups and downs affected the planet's life. 

Originally published on Live Science.

Life on Earth may have begun with a flash of lightning.

No, an errant thunderbolt didn't literally animate the world's first microbes (sorry, Dr. Frankenstein). But according to a new study published Tuesday (March 16) in the journal Nature Communications, trillions of lightning strikes over a billion of years of Earth's early history may have helped unlock crucial phosphorus compounds that paved the way for life on Earth.

"In our study, we show for the first time that lightning strikes were likely a significant source of reactive phosphorus on Earth around the time that life formed [3.5 billion to 4.5 billion years ago]," lead study author Benjamin Hess, a graduate student at Yale University's Department of Earth and Planetary Sciences, told Live Science. "Lightning strikes may have therefore played a role in providing phosphorus for the emergence of life on Earth."

Related: Earth has a hidden layer, and no one knows exactly what it is

Bombarded with life?

How does a bolt from the blue lead to terrestrial life? It's all about the phosphorus — or rather, the organic materials that phosphorus atoms can make when combined with other bio-essential elements.

Take phosphates, for example — ions composed of three oxygen atoms and one phosphorus atom, which are crucial to all known forms of life. Phosphates form the backbones of DNA, RNA and ATP (the chief source of energy for cells), and are major components of bones, teeth and cell membranes.

But about 4 billion years ago, while there was likely plenty of water and carbon dioxide in the atmosphere to work with, which are also essential for life's fundamental molecules, most of the planet's natural phosphorus was bound up in insoluble rock, and impossible to combine into organic phosphates. How, then, did Earth acquire these critical compounds?

One theory holds that early Earth got its phosphorous from meteors carrying a mineral called schreibersite, which is made partly of phosphorous and is soluble in water; if loads of schreibersite meteorites crashed into Earth over millions or billions of years, then enough phosphorus could be released into a concentrated area to create the right conditions for biological life, according to the new study.

However, about 3.5 billion to 4.5 billion years ago, when life on Earth emerged, the rate of meteor strikes on Earth dropped "exponentially" as most of our solar system's planets and moons had largely taken shape, Hess said. This fact complicates the interstellar phosphorus theory. 

However, there is another way to make schreibersite, right here on Earth, Hess said. All it takes is some land, a cloud and a few trillion jolts of lightning.

Billions of bolts

Lightning strikes can heat up surfaces to nearly 5,000 degrees Fahrenheit (2,760 degrees Celsius), forging new minerals that weren't there before. In the new study, Hess and his colleagues examined a lightning-blasted clump of rock, called fulgurite, which was previously excavated from a site in Illinois. The team found that little balls of schreibersite had formed within the rock, along with a host of other glassy minerals.

With tentative proof in hand that lightning strikes can create phosphorus-rich schreibersite, the team next had to calculate whether enough lightning could have struck early Earth to release a significant amount of the element into the environment. Using models of Earth's early atmosphere, the researchers estimated how many lightning strikes may have fallen over the planet each year.

Today, about 560 million lightning bolts flash over the planet a year; 4 billion years ago, when Earth's atmosphere was significantly richer in the greenhouse gas CO2 (and therefore hotter and more prone to storms), it's likely that anywhere from 1 billion to 5 billion bolts flashed each year, the team calculated. Of those bolts, the team estimated that between 100 million and 1 billion bolts struck land each year (the rest discharged above the oceans).

And, over a billion years, up to a quintillion (a 1 followed by 18 zeros) lightning strikes may have hit our young planet, each one releasing a bit of usable phosphorus, Hess said. The team calculated that, between 4.5 billion and 3.5 billion years ago, lightning strikes alone could have given Earth anywhere from 250 to 25,000 pounds of phosphorus (110 to 11,000 kilograms) per year.

That's a huge range, with a lot of uncertainty about the conditions of early Earth built into it. But Hess said that even the lowest quantity of phosphorus could have made a difference for the emergence of life.

"For life to form, there just needs to be one location that has the right ingredients," Hess told Live Science. "If [250 lbs.] of phosphorus a year were concentrated in a single tropical island arc, then yes, it may well have been enough. But it's more likely that will happen if there are many such locations."

Whether lightning did strike enough exposed land on early Earth to make an impact on life is a question that can never be fully answered. However, the new study shows that, mathematically, it was at least possible. 

It may be that a combination of asteroid impacts and lightning strikes ultimately gave Earth the phosphorus it needed to weave the first bio-essential molecules, such as DNA and RNA, the researchers concluded. But further studies of early terrestrial life should take care not to strike lightning from the record.

Originally published on Live Science.

Star explosions may have played a greater role in Earth's climate history than scientists thought.

Nearby supernovas have left a series of possible fingerprints in the tree-ring record here on Earth over the past 40,000 years, potentially disrupting our planet's climate multiple times over this span, a new study reports.

"These are extreme events, and their potential effects seem to match tree-ring records," study author Robert Brakenridge, a senior research associate at the Institute of Arctic and Alpine Research at the University of Colorado Boulder, said in a statement.

Supernova photos: Great images of star explosions

Brakenridge compiled a list of 18 supernovas — violent explosions that mark the deaths of certain kinds of stars — that occurred within about 4,900 light-years of Earth. He then compared the estimated timing of these cosmic events with spikes in carbon-14, as observed in the tree-ring record.

Carbon-14 is a radioactive isotope of carbon that contains eight neutrons in its atomic nucleus instead of the usual six. Carbon-14 is rare on Earth, and it doesn't occur here naturally without some outside influence — namely, high-energy radiation streaming in from deep space, which can convert some of the "normal" carbon in our atmosphere to carbon-14 (which explains why this isotope is also known as radiocarbon).

"There’s generally a steady amount year after year," Brakenridge said. "Trees pick up carbon dioxide, and some of that carbon will be radiocarbon."

The amount of radiocarbon is not always steady, however. Scientists have spotted spikes in the tree-ring record, which have generally been attributed to powerful flares from our own sun. But Brakenridge suspected that supernovas could be involved, so he investigated a possible link.

And he found a tantalizing but tentative one: Eight of the closest supernovas on his list occurred around the same time as a brief radiocarbon spike. The association was especially strong for four supernovas, including one 13,000 years ago that ended the life of a star in the Vela constellation about 815 light-years from Earth.

Shortly after that explosion, radiocarbon levels shot up briefly by about 3% in Earth's atmosphere, Brakenridge found.

The results are not conclusive, given the various uncertainties involved. For example, it's difficult to date supernovas precisely; the inferred timing of the Vela explosion may be off by as much as 1,500 years, Brakenridge said. But he thinks that the new results, which were published online last week in the International Journal of Astrobiology, show that more research into a supernova-radiocarbon link is warranted.

“What keeps me going is when I look at the terrestrial record and I say, 'My God, the predicted and modeled effects do appear to be there," Brakenridge said.  

He's not the only scientist to suggest that supernovas may have significantly affected life on Earth. Other studies have postulated that nearby star explosions have caused or contributed to some mass extinctions, by altering our planet's atmosphere and causing climatic shifts.

Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook. 

The ozone hole above Antarctica, where the sun's harmful ultraviolet (UV) rays bust through an otherwise sunscreened stratosphere, has shrunk to its smallest size on record going back to 1982, scientists have found.

Typically, at this time of year, the hole in the ozone — a layer made up of molecules containing three oxygen atoms — grows to about 8 million square miles (20 million square kilometers), NASA said. That's bigger than Russia.

But unusually warm weather in the Southern Hemisphere means that the hole only extended less than 3.9 million square miles (10 million square kilometers) for most of September until now, according to a statement from NASA. 

Related: 8 Ways Global Warming Is Already Changing the World

"This warming that occurred is great news for the Southern Hemisphere because ozone is going to be higher and UV levels will be lower," Paul Newman, chief scientist for Earth Sciences at NASA's Goddard Space Flight Center in Greenbelt, Maryland, told Live Science.

Here's how it works: During the winter months in the Southern Hemisphere, clouds form in the stratosphere, which extends from about 6 to 31 miles (9.5 to 50 km) above Earth's surface. There, even the smallest amount of visible light from the sun breaks apart chlorine gas into chlorine atoms; those atoms are considered "reactive" and can chemically destroy ozone molecules. So, the ozone hole over Antarctica tends to be much bigger in the southern winter. 

When temperatures over Antarctica start to warm up, the polar clouds in the stratosphere dissipate, meaning that there's no place for those ozone-annihilating chemical reactions to take place. This year, exceptionally warm weather put the nix on ozone-smashing, keeping that ozone hole super-small.

"This is as small as we were seeing back in the early '80s," Newman said. (The ozone hole was so small that it wasn't even discovered until 1985.)

The ozone-busting chlorine gas mainly comes from chlorofluorocarbons (CFCs) that were manufactured until the U.S. ban beginning in 1996. Even so, some types of CFCs can stay in the atmosphere for more than 100 years, Newman said.

If higher temperatures are good for the ozone layer, does that mean that hole will get even smaller as humans pump greenhouse gases like carbon dioxide into the atmosphere? 

Not quite, Newman said. Turns out, carbon dioxide has the opposite effect in the stratosphere as it does in the layer closer to the ground called the troposphere. The CO2 in the stratosphere absorbs and then emits that heat out into space, Newman explained, adding that this layer of the atmosphere is actually cooling off. 

• Images of Melt: Earth's Vanishing Ice
• In Photos: Antarctica's Larsen C Ice Shelf Through Time
• Icy Images: Antarctica Will Amaze You in Incredible Aerial Views

Originally published on Live Science.

A dense layer of molecules and electrically charged particles, called the ionosphere, hangs in the Earth's upper atmosphere starting at about 35 miles (60 kilometers) above the planet's surface and stretching out beyond 620 miles (1,000 km). Solar radiation coming from above buffets particles suspended in the atmospheric layer. Radio signals from below bounce off the ionosphere back to instruments on the ground. Where the ionosphere overlaps with magnetic fields, the sky erupts in brilliant light displays that are incredible to behold.

Where is the ionosphere?

Several distinct layers make up Earth's atmosphere, including the mesosphere, which starts 31 miles (50 km) up, and the thermosphere, which starts at 53 miles (85 km) up. The ionosphere consists of three sections within the mesosphere and thermosphere, labeled the D, E and F layers, according to the UCAR Center for Science Education.

Extreme ultraviolet radiation and X-rays from the sun bombard these upper regions of the atmosphere, striking the atoms and molecules held within those layers. The powerful radiation dislodges negatively charged electrons from the particles, altering those particles' electrical charge. The resulting cloud of free electrons and charged particles, called ions, led to the name "ionosphere." The ionized gas, or plasma, mixes with the denser, neutral atmosphere.

The concentration of ions in the ionosphere varies with the amount of solar radiation bearing down on the Earth. The ionosphere grows dense with charged particles during the day, but that density subsides at night as charged particles recombine with displaced electrons. Entire layers of the ionosphere appear and disappear during this daily cycle, according to NASA. Solar radiation also fluctuates over an 11-year period, meaning the sun may put out more or less radiation depending on the year.

Explosive solar flares and gusts of solar wind stir up sudden changes in the ionosphere, teaming up with high-altitude winds and severe weather systems brewing on the Earth below.

Light up the skies

The scorching-hot surface of the sun expels streams of highly charged particles, and these streams are known as solar wind. According to NASA's Marshall Space Flight Center, solar wind flies through space at about 25 miles (40 km) per second. Upon reaching the Earth's magnetic field and the ionosphere below, solar winds set off a colorful chemical reaction in the night sky called an aurora.

When solar winds whip across Earth, the planet stays shielded behind its magnetic field, also known as the magnetosphere. Generated by churning molten iron in the Earth's core, the magnetosphere sends solar radiation racing toward either pole. There, the charged particles collide with chemicals swirling in the ionosphere, generating the spellbinding auroras.

Scientists have found that the sun's own magnetic field squishes the Earth's weaker one, shifting auroras toward the night side of the planet, as reported by Popular Mechanics.

Near the Arctic and Antarctic circles, auroras streak across the sky every night, according to National Geographic. The colorful curtains of light, known as the aurora borealis and aurora australis, respectively, hang about 620 miles (1,000 km) above the Earth's surface. The auroras glow green-yellow when ions strike oxygen particles in the lower ionosphere. Reddish light often blooms along the auroras' edges, and purples and blues also appear in the nighttime sky, though this happens rarely.

"The cause of aurora is somewhat known, but it is not entirely resolved," said Toshi Nishimura, a geophysicist at Boston University. "For example, what causes a particular type of color of aurora, such as purple, is still a mystery."

Who is Steve?

Beyond auroras, the ionosphere also plays host to other impressive light shows.

In 2016, citizen scientists spotted a particularly eye-catching phenomena, which scientists struggled to explain, Live Science sister-site Space.com previously reported. Bright rivers of white and pinkish light flowed over Canada, which is farther south than most auroras appear. Occasionally, dashes of green joined the mix. The mysterious lights were named Steve in homage to the animated movie "Over the Hedge" and were later rebranded as the "Strong Thermal Emission Velocity Enhancement" ⁠— still STEVE for short.

"We've been studying the aurora for hundreds of years, and we couldn't, and still can't, explain what Steve is," said Gareth Perry, a space weather scientist at the New Jersey Institute of Technology. "It's interesting because its emissions and properties are unlike anything else we observe, at least with optics, in the ionosphere."

According to a 2019 study in the journal Geophysical Research Letters, the green streaks within STEVE may develop similarly to how traditional auroras form, as charged particles rain down upon the atmosphere. In STEVE, however, the river of light seems to glow when particles within the ionosphere collide and generate heat among themselves.

Communication and navigation

Though reactions in the ionosphere paint the sky with brilliant hues, they can also disrupt radio signals, interfere with navigational systems and sometimes cause widespread power blackouts.

The ionosphere reflects radio transmissions below 10 megahertz, allowing the military, airlines and scientists to link radar and communication systems over long distances. These systems work best when the ionosphere is smooth, like a mirror, but they can be disrupted by irregularities in the plasma. GPS transmissions pass through the ionosphere and therefore bear the same vulnerabilities.

"During large geomagnetic storms, or space weather events, currents [in the ionosphere] can induce other currents in the ground, electrical grids, pipelines, etc. and wreak havoc," Perry said. One such solar storm caused the famous Quebec blackout of 1989. "Thirty years later, our electrical systems are still vulnerable to such events."

Scientists study the ionosphere using radars, cameras, satellite-bound instruments and computer models to better understand the region's physical and chemical dynamics. Armed with this knowledge, they hope to better predict disruptions in the ionosphere and prevent problems that can cause on the ground below.

Additional resources:

• Check out a slideshow of fantastic auroras from National Geographic.
• Learn how GPS works with the Smithsonian National Air and Space Museum.
• Watch an animation of the Earth's magnetic field in action, from Nova and the Khan Academy.

Three years ago, a mysterious purplish glow arced across the Canadian skies. The light show was a completely unknown celestial phenomenon, so it was given a name befitting its beauty and grandeur: Steve.

Now, scientists have finally pinpointed what causes the phenomenon's glowing ribbons of reddish purple and green: magnetic waves, winds of hot plasma and showers of electrons in regions they normally never appear.

A brief history of STEVE

On July 25, 2016, observers noticed an odd type of atmospheric light display illuminating the night sky in the Northern Hemisphere. They quickly realized that this was no ordinary aurora and gave it a new name inspired by the film "Over the Hedge" (DreamWorks Animation, 2006); a group of forest animals, confounded by a hedge for the first time, name the unfamiliar object "Steve." (Astronomers later changed that name to STEVE, an acronym for strong thermal emission velocity enhancement.)

Preliminary analysis of STEVE found that its optical effects came about differently than an aurora's, but scientists couldn't say what exactly was taking place. [Northern Lights: 8 Dazzling Facts About Auroras]

Auroras can trace their origins to the sun, when sunspots spit out clouds of protons and electrons that speed toward Earth on solar winds. Once these charged particles reach the planet, its magnetic field draws them toward the North and South poles. As the particles leave the magnetosphere and bombard the planet's upper atmosphere, they interact with elements such as oxygen and nitrogen to generate swirling ribbons of light.

But STEVE's light shows are different from a typical aurora's. STEVE appears farther south, and over more-populated areas, than most auroras do. And unlike an aurora and its trademark greenish swirls that undulate horizontally, STEVE produces a towering vertical purplish or green band, sometimes accompanied by a column of short bars resembling a picket fence, according to the new study.

"Completely unknown"

In a prior study published in 2018, the same researchers found that STEVE originated in the ionosphere, the zone stretching from about 50 to 375 miles (80 to 600 kilometers) above the ground, where auroras form.

But even though STEVE appeared during the same solar-powered magnetic storms that produced auroras, most of the newfound phenomenon's glowing appearance was not the result of charged particles slamming into Earth's upper atmosphere. That conclusion comes from evidence gathered by satellites that passed through a STEVE event in 2008.

The new study used that 2008 data, along with satellite data and ground observations from two other STEVE events, to identify two different processes that shape STEVE's light ribbon and picket fence.

STEVE's vertical ribbons are illuminated not by a rain of charged particles falling into the atmosphere, but by friction caused by hot plasma flows and powerful magnetic waves about 15,000 miles (25,000 km) above Earth, according to the study. Heat from these flows energizes particles so that they generate purple light, a mechanism similar to the illumination of incandescent lightbulbs.

While aurora glows occur when electrons and protons fall into Earth's atmosphere, "the STEVE atmospheric glow comes from heating without particle precipitation," study co-author Bea Gallardo-Lacourt, a space physicist at the University of Calgary in Canada, said in a statement.

STEVE's green picket fence, on the other hand, forms as auroras do: when electrons rain down on the upper atmosphere. However, this occurs far south of the latitudes where auroras usually form, "so it's indeed unique," Gallardo-Lacourt said.

This distinctive picket fence also appeared in skies over the Northern and Southern hemispheres at the same time, the authors wrote. This demonstrates that the energy source fueling STEVE is abundant enough to create simultaneous light shows in both hemispheres, the study authors said.

But scientists still don’t know why the phenomenon appears so much farther south than auroras do, meaning that STEVE retains a little of its mystery.

The findings were published online April 16 in the journal Geophysical Research Letters.

• Aurora Photos: Northern Lights Dazzle in Night-Sky Images
• Aurora Borealis: What Causes the Northern Lights and Where to See Them
• Aurora Photos: See Breathtaking Views of the Northern Lights

Originally published on Live Science.

Nearly 80 years on, impacts from the violent bombings of World War II are still felt around the globe. Christopher Scott would know —two of his aunts were killed at just 9 and 11 years of age during the London Blitz, Nazi Germany's eight-month onslaught against the British.

Those aerial raids didn't just have rippling effects through generations of families. Scott, who is a space and atmospheric physicist at the University of Reading in the U.K., recently found that the bombs were felt at the edge of space, too.

By combing through archival data, Scott discovered that shock waves from the bombs briefly weakened the ionosphere, the outermost layer of Earth's atmosphere. [10 of the Most Powerful Explosions Ever]

From lightning to bombs

Between around 50 and 375 miles (80 and 600 kilometers) above the ground, the ionosphere is where auroras are created and where astronauts on board the International Space Station live. Atoms of gas in this layer of the atmosphere get excited by solar radiation, forming electrically charged ions. The density and altitude of electrons, the negatively charged particles, in the ionosphere can fluctuate. [Infographic: Earth's Atmosphere Top to Bottom]

"The ionosphere is far more variable than can be explained by solar activity," Scott told Live Science.

Scott's previous research had shown that lightning could enhance the ionosphere. He wanted to find out if this was due to the explosive energy of lightning or its electrical charge. So, he set out to look for well-documented explosions on the ground, and to compare the historical data with archival data from the Radio Research Centre in Slough, where scientists had measured the density ionosphere using radio pulses sent over a range of shortwave frequencies.

Scott said he originally intended to look at the effects of the London Blitz, but little information survives about the timing and munitions used for these raids. As an alternative, Scott's colleague Patrick Major, a historian at the University of Reading, provided a database on the bombing of Berlin between 1943 and 1944 and directed Scott to other data sets about Allied air raids in Europe.

Shock waves

Each raid released the energy of at least 300 lightning strikes, Scott said, and historical accounts from the ground attest to the far-reaching power of bombs like the 22,000-lb. (10,000 kilogram) British "Grand Slam."

"Residents under the bombs would routinely recall being thrown through the air by the pressure waves of air mines exploding, and window casements and doors would be blown off their hinges," Major said in a news release.

When the researchers looked at the ionosphere-response records around the time of 152 large Allied air raids in Europe, they found that the electron concentration significantly decreased due to the shock waves from the bombs. The findings were published today (Sept. 25) in the journal Annales Geophysicae.

"I was able to see an effect in the U.K. ionospheric records from bombing over 1,000 km [620 miles] away," Scott said. "I was surprised by that."

Ingo Mueller-Wodarg, a planetary scientist at Imperial College London who was not involved in the study, said the research is "a neat demonstration of how the ionosphere is affected by activity on the ground, despite being many tens to hundreds of kilometers above the ground."

The effects of the shock waves would be temporary, Scott said, lasting under a day. "The ionosphere is largely controlled by solar radiation," he told Live Science. "The bombing represents a small impact by comparison."

Scott added that the ionosphere weakening may have affected the efficiency of shortwave radio communication, which relied on the ionosphere to reflect the signals over long distances.

More modern technologies, such as GPS, are affected by disturbances in the ionosphere. Another study published earlier this year found that the massive shock wave from a 2017 launch of a SpaceX Falcon 9 rocket created a temporary hole in the ionosphere, which may have disrupted navigation signals for an hour or two afterward.

Next steps

Mueller-Wodarg noted that there has long been speculation on whether earthquakes affect the ionosphere, with mixed results. "This study lends strong support to the suggestion that events on the ground which generate any kind of shock wave or strong impulses should be able to be felt in the ionosphere," Mueller-Wodargtold Live Science.

Scott said he also wants to find out if thunderstorms, volcanoes and earthquakes can be detected using similar methods.

He is also currently digitizing earlier U.K. ionospheric data with the intention to put this information online, so that volunteers can help identify more effects on the ionosphere. Doing so might help Scott understand why lightning has an impact on the ionosphere.

"The ionospheric layer that we saw responding to the bombing was much higher than the one used in the lightning study, as it was the only one for which digital data currently exist," Scott said. "This is one of the reasons why I want to digitize the ionospheric data, so that we can look to see if the layer that was enhanced by lightning is also enhanced by the bombing. Only then can we say for sure if the lightning effect is due to shock waves or an electrical current —or both."

Original article on Live Science

A moderate geomagnetic storm will lash the planet tonight, according to a National Oceanic and Atmospheric Administration (NOAA) alert released yesterday (Sept. 10).

A stream of high-energy particles have escaped through a hole in the sun's corona and are streaming our way. While a sufficiently severe solar storm would pose a significant threat to modern infrastructure, there's no reason to worry about this event. It will, however, offer people in parts of the U.S. and Canada a chance to spot rare auroras flickering at relatively low altitudes.

The aurora borealis happens, as Live Science has previously reported, when charged particles from the sun slam into the particles of a region of Earth's upper atmosphere called the ionosphere. Particles floating between 60 and 600 miles (96 to 960 kilometers) above the planet's surface absorb energy from those charged particles, and re-emit that energy in the form of colored light. From Earth, the effect looks like towering waves of light dancing across the sky. [Northern Lights: 8 Dazzling Facts About Auroras]

A NOAA map, pictured below, highlights the areas where auroras are most likely to appear during this storm. The region betwen the green line (marked kp=5) and the yellow line (marked hp=7) has the highest chance of aurora activity.

In the U.S., that includes Washington state, northern Idaho, Montana, northeastern Wyoming, parts of southern North Dakota, South Dakota, part of northeast Nebraska, southern Minnesota, northern Iowa, much of Wisconsin, northern Illinois (including Chicago), Michigan's lower peninsula, upstate New York, Vermont, New Hampshire and Maine. Tiny slivers of northern Ohio and Pennsylvania, as well as far-northeastern Oregon, also fall within that aurora zone.

Most of Canada's most populous regions also fall within the possible aurora zone, including southern British Columbia and an area of southern Ontario and Quebec that includes Ottawa, Toronto and Montreal.

On the Eurasian continent, the northern British Isles, parts of Scandinavia and central Russia all fall within the most likely aurora zone.

Originally published on Live Science.

Late at night on July 25, 2016, a thin river of purple light slashed through the skies of northern Canada in an arc that seemed to stretch hundreds of miles into space. It was a magnificent, mysterious, borderline-miraculous sight, and the group of citizen skywatchers who witnessed it decided to give the phenomenon a fittingly majestic name: "Steve."

Given its coincidence with the northern lights, Steve was just thought to be part of the aurora — the shimmering sheets of nighttime color that appear in the sky when charged plasma particles streak out of the sun, sail across space on solar winds and jolt down Earth's magnetic field toward the planet's poles. However, a new study published today (Aug. 20) in the journal Geophysical Research Letters suggests that such a simple explanation might not apply. [Aurora Images: See Breathtaking Views of the Northern Lights]

According to researchers at the University of Calgary in Canada and the University of California, Los Angeles, Steve does not contain the telltale traces of charged particles blasting through Earth's atmosphere that auroras do. Steve, therefore, is not an aurora at all, but something entirely different: a mysterious, largely unexplained phenomenon that the researchers have dubbed a "sky glow."

"Our main conclusion is that STEVE is not an aurora," lead study author Bea Gallardo-Lacourt, a space physicist at the University of Calgary in Alberta, Canada, said in a statement. "So right now, we know very little about it. And that's the cool thing."

There's something about Steve

To photographers and stargazers in northern climes, Steve has been a familiar night phenomenon for decades. But the mysterious ribbons of light only entered the scientific literature for the first time earlier this year, thanks largely to Steve-tracking efforts coordinated by Facebook groups like the Alberta Aurora Chasers. Writing in the journal Science Advances in March, researchers (including Gallardo-Lacourt) decided to keep the name "Steve" as the official nomenclature for the colorful happening, but they changed it to an acronym standing for "Strong Thermal Emission Velocity Enhancement" — aka STEVE.

Compared to the northern lights — which tend to shimmer in broad bands of green, blue or reddish light depending on their altitude — Steve is remarkably slim, usually appearing as a single ribbon of purplish-white light. What this ribbon lacks in girth, it makes up for in length; unlike the wavy northern lights, Steve appears to stab straight upward into the night sky, often spanning more than 600 miles (1,000 kilometers).

This study found that, for all its quirks, Steve seemed to look and act like its more familiar cousin, the aurora borealis. When a European Space Agency satellite passed directly through Steve in July 2016, instruments on board confirmed that a pipeline of incredibly fast, ridiculously hot gas was slicing through the atmosphere there. At about 200 miles (300 km) above Earth, the air inside Steve blazed about 5,500 degrees Fahrenheit (3,000 degrees Celsius) hotter than the air on each side, and moved about 500 times faster. This band of hot, surging gas was about 16 miles (25 km) wide.

On March 28, 2018, Steve again appeared in the skies of northern Canada and happened to fall within the sight of both ground- and sky-based recording equipment. In the new University of Calgary study, Gallardo-Lacourt and her colleagues decided to use the data recorded that night to further investigate Steve's mysterious origins.

A particular mystery

For their new study, the team combined images taken by a network of ground-based cameras with data collected from one of the National Oceanic and Atmospheric Administration's Polar-orbiting Operational Environmental Satellites, which were equipped with instruments capable of detecting charged particles descending through Earth's atmosphere.

Contrary to the findings from the Steve study published earlier this year, the satellite did not detect any charged particles raining down toward Earth's magnetic-field lines, indicating that whatever created Steve did not follow the same rules as the solar particles that create the aurora.

According to the authors, that means Steve is likely not a feature of the aurora but is actually something completely different. What could that something be? According to Gallardo-Lacourt, that's "completely unknown." But, for the sake of keeping the conversation going, she and her colleagues dubbed the mysterious force a "sky glow."

"Based on our results, we assert that STEVE is likely related to an ionospheric process," the researchers wrote in their study, referring to the level of Earth's atmosphere that extends between 50 and 600 miles (80 to 1,000 km) above Earth's surface and sits directly below the planet's magnetic field. More observations taken at different levels of the atmosphere will be required to fully tease out the causes of that mystery of mysteries — good old Steve.

Originally published on Live Science.

Editor's Note: This story was updated at 1:35 p.m. E.T.

Mysterious, ghostlike "whistler waves" that are normally created by lightning could protect nuclear fusion reactors from runaway electrons, new research suggests.

These whistler waves are naturally found high above ground in the ionosphere — a layer of Earth's atmosphere about 50 to 600 miles (80 an1000 kilometers) above the planet's surface. These ghostly whistler waves form when lightning bolts generate pulses of electromagnetic waves that travel between the Northern and Southern hemispheres. These waves change in frequency as they cross the globe, and when these light signals are converted to audio signals, they sound like whistles.

Now these whistler waves have been discovered in the hot plasma inside a tokamak — the doughnut-shaped machine where nuclear fusion reactions take place — according to a recent study published April 11 in the journal Physical Review Letters.

Because whistlers can scatter and impede high-speed electrons, they could provide a new way to prevent runaway electrons from damaging the inside of a tokamak.

Fusion power

In nuclear fusion reactions, which power the sun and stars, atoms slam together, fusing into larger atoms while releasing energy. For decades, researchers have been trying to harness fusion energy on Earth, using powerful magnetic fields inside tokamaks to corral doughnut-shaped clouds of hot plasma — a weird phase of matter that consists of electrically charged gas.

Inside the tokamak, electric fields can propel electrons faster and faster. But as these high-speed electrons fly through the plasma, they can't slow down. Normally, objects moving through a gas or liquid  feel a drag force that increases with speed. The faster you drive your car, for example, the more wind resistance you run into. But in plasma, drag force decreases with speed, allowing electrons to accelerate to near light speed, damaging the tokamak.

Researchers already have a few techniques to mitigate runaways, said Don Spong, a physicist at Oak Ridge National Laboratory in Tennessee and a co-author of the new study. They can use artificial intelligence algorithms to monitor and adjust the density of the plasma to prevent electrons from accelerating too fast. If there are still runaways, they can inject pellets of frozen neon into the plasma, which increases the plasma density and slows runaway electrons.

But whistler waves could be yet another way to rein in runaway electrons. "We ideally want to avoid disruptions and runaways," Spong said. "But if they occur, we would like multiple tools available for dealing with them."

Stopping runaways

In the tokamak at the DIII-D National Fusion Facility in San Diego, Spong's research team detected, for the first time, whistler waves being produced by runaway electrons.

Plasma, he explained, is like a piece of Jell-O with many modes of vibration. If some runaway electrons have just the right velocity, they excite one of these modes and trigger whistler waves — similar to how driving an old car at just the right speed can cause the dashboard to vibrate. 

"What we would like to do is reverse engineer that process and put those waves on the outside [of the plasma] to scatter the runaways," Spong said.

By better understanding how runaways create whistlers, the researchers hope they can reverse the process — using an external antenna to generate whistlers that can scatter the electrons and prevent them from getting too fast.

The researchers still need to further explore the relationship between runaways and whistlers, Spong said, for example, by identifying what frequencies and wavelengths work best to inhibit runaways and by studying what happens in the denser plasma needed for fusion reactors.

Of course, suppressing runaway electrons is just one hurdle to creating clean energy from nuclear fusion. Right now, fusion reactors require more energyto heat plasma than is produced by the fusion. To reach the breakeven point, researchers still have to figure out how to get plasma to stay hot without having to add heat.

But Spong is optimistic about fusion energy. "I'm a believer that it's achievable."

In 2025, the ITER project in southern France is slated to begin experiments. and scientists hope it will be the first fusion machine to produce more energy than is used to heat the plasma. Several groups have set their sights on achieving net positive fusion energy by 2050. And a new collaboration between MIT and a company called Commonwealth Fusion Systems announced that the partners hope to put nuclear fusion on the grid in 15 years.

Editor's Note: This story was updated to note that light signals, rather than light frequencies, are converted to audio signals.

Originally published on Live Science.

Wildfires can fuel "dirty" thunderstorms that fill the stratosphere with as much smoke as a volcanic eruption.

That revelation comes from a study on the biggest fire-fueled thunderstorm event on record, which occurred on the night of Aug. 12, 2017, in British Columbia, Canada.

Last year was a record breaker for wildfires in that region. And on that August evening, the heat from fires burning in relatively remote forests in British Columbia combined with the right atmospheric conditions to generate a series of four thunderstorms in a 5-hour period. [Infographic: Earth's Atmosphere Top to Bottom]

These fire storms are called pyrocumulonimbus storms, or pyroCbs. Like regular thunderstorms, they produce lightning and are very tall. But pyroCbs are also filled with smoke.

"You end up with this very dirty thunderstorm," David Peterson, a meteorologist with the U.S. Naval Research Laboratory who presented his findings last week at the annual meeting of the European Geosciences Union in Vienna. "Essentially, this is a giant chimney taking smoke from the surface to high altitudes, at least to aircraft-cruising altitudes."

The enormous smoke plume from the pyroCbs in British Columbia drifted over Europe and then eventually encircled the entire Northern Hemisphere. Using satellite data, Peterson's team observed the signal from this smoke in the lower stratosphere — the second layer of Earth's atmosphere, above the troposphere — for several months later.

"This was the mother of all pyroCbs," Peterson said. "Normally, when you see something like this, you think volcanic eruptions — that's what normally puts a lot of material into the stratosphere — but it's all coming from these wildfire-driven thunderstorms."

For comparison, the explosive 2008 eruption of Mount Kasatochi, an island volcano in Alaska, sent about 0.7 to 0.9 teragrams (nearly 1 million tons) of aerosols — tiny, suspended particles — into the stratosphere, Peterson said. For months afterward, people around the Northern Hemisphere documented unusually colored sunsets, thanks to the sulfate aerosols and ash the volcano injected into the atmosphere.

Peterson's team estimated that the British Columbia pyroCb event sent about 0.1 to 0.3 teragrams (about 200,000 tons) of aerosols into the stratosphere — which is comparable to the amount seen with a moderate volcanic event, and more than the total stratospheric impact of the entire 2013 fire season in North America, he said.

It's well known that catastrophic volcanoes can influence the global climate. The huge 1991 eruption of Mount Pinatubo in the Philippines, one of the largest in living memory, lowered temperatures around the world by an average of 0.9 degrees Fahrenheit (0.5 degrees Celsius).

While such major volcanic events are sporadic, Peterson said, pyroCb events occur every year. But scientists have not studied these storms enough to understand their potential impact on the climate.

Original article on Live Science.

Sprinkling large amounts of salt into the atmosphere could stave off climate change, a group of researchers has proposed.

They've suggested that, because salt is highly reflective, it could potentially reflect sunlight back into outer space, helping to cool the Earth, they wrote in a report presented at the Lunar and Planetary Science Conference in Texas on March 21.

But other climate scientists aren't so sure. This idea falls into the category of geoengineering — a deliberate, large-scale attempt to change the environment as a means to counteract climate change. [Top 10 Craziest Environmental Ideas]

"It's an interesting idea," Michael Mann, a distinguished professor of meteorology at Penn State, told Live Science. But "most of these [geoengineering] schemes,though potentially appealing at the surface, are seen to be fraught with potential unintended consequences when you look at them in more detail."

Salty idea

The salty proposal is more of a last-ditch effort that could be used to offset climate change, in case humans fail to significantly lower greenhouse gas emissions, such as those of carbon dioxide, that are contributing to Earth's rising temperatures, Science magazine reported. The idea is to seed salt into the upper troposphere, the atmospheric layer most commercial airplanes fly over because of its weather conditions and clouds.

The idea was put forward, in part, by Robert Nelson, a senior scientist at the Planetary Science Institute, a nonprofit whose scientists study planetary systems, including the solar system.

Their proposal is hardly the first geoengineering idea out there. Other scientists have considered injecting tiny particles known as aerosols into the stratosphere, the region above the troposphere, as a way to cool the planet, Science magazine reported.

In effect, these particles — whether aerosols or kitchen table salt — could act like natural aerosols that cool the planet after a volcanic eruption. For instance, a series of stupendous eruptions from the Icelandic volcano Eldgjá from A.D. 939 to 940 led to one of the coldest summers the Northern Hemisphere had experienced in 1,500 years, Live Science previously reported.

However, many of the aerosols scientists have suggested using, such as diamond dust or alumina, are harmful to the ozone (a layer that protects the Earth's surface from some of the sun's ultraviolet rays) and human health. But in 2015, while studying evaporated salts on the surfaces of solar system bodies, such as the dwarf planet Ceres, Nelson realized that table salt was a possibility. It's more reflective than alumina and harmless to humans. In addition, if it were ground up into small particles and released into the upper troposphere, the salt would not block infrared heat released by Earth, which also helps the planet cool, he said.

But this proposal is still in its early stages, scientists told Live Science.

"It is hard to emphasize enough just how much further research would be needed to verify its applicability," said Kelly McCusker, a climate scientist at Rhodium Group, an independent research firm in New York City.

For starters, salt (NaCl) contains chlorine, "which is a constituent of ozone-depleting CFCs [chlorofluorocarbons] — so this could actually worsen ozone depletion," Mann said. While ozone depletion does not cause climate change, it's harmful to human health because it lets ultraviolet radiation into Earth, according to the Union of Concerned Scientists.

Simone Tilmes, a project scientist at the National Center for Atmospheric Research in Boulder, Colorado, added that salt often includes iodine, a reactive element that could not just impact ozone chemistry in the troposphere but also affect chemical reactions in the stratosphere.

Moreover, "the salt's reflectance has thus far been measured in a laboratory setting, and we don't know how its properties would change upon delivery (through a nozzle or some other device)," McCusker told Live Science in an email.

It's also unclear "how much [salt] would be needed to be deployed to reduce surface temperature, or how it would interact with water vapor, clouds and the atmosphere in general, to name just a few unknowns," McCusker said. [Doomsday: 9 Real Ways Earth Could End]

McCusker and Mann agreed that the best way to fight human-caused climate change is to reduce greenhouse gas emissions worldwide.

"The only safe way to tackle climate change is to address the root cause — our continued reliance on the burning of fossil fuels," Mann said.

Nelson couldn't be reached for comment, but told Science magazine that he plans to further study salt's properties to see how feasible the project is. What's more, he would like to engage with the public before implementing the salty mission, he said. But Nelson also acknowledged that salt can't solve Earth's long-term climate change challenges.

"This is a palliative, not a solution, somewhat analogous to the application of morphine in a medical situation," he and his colleagues wrote in the report.

Original article on Live Science.

Efforts to heal the hole in Earth's ozone layer over Antarctica appear to be paying off, according to a new, first-of-its-kind study that looked directly at ozone-destroying chemicals in the atmosphere.  

Earth's ozone layer protects the planet's surface from some of the sun's more harmful rays that can cause cancer and cataracts in humans, and damage plant life, according to NASA. In the mid-1980s, researchers identified a massive hole in the ozone layer over Antarctica and determined that it had been caused largely by human-produced chemicals called chlorofluorocarbons (CFCs). 

Previous satellite observations have observed changes in the size of the ozone hole, noting that it can grow and shrink from year to year. But the new study is the first to directly measure changes in the amount of chlorine — the main CFC byproduct responsible for ozone depletion — in the atmosphere above Antarctica, according to a statement from NASA. The study showed a 20-percent decrease in ozone depletion due to chlorine between 2005 and 2016. [Earth's Atmosphere: Composition, Climate & Weather]

The new study looked at ozone data collected between 2005 and 2016 by the Microwave Limb Sounder (MLS) instrument aboard the Aura satellite. The instrument cannot directly detect chlorine atoms, but instead detects hydrochloric acid, which forms when chlorine atoms react with methane, and then bond with hydrogen. When Antarctica is bathed in sunlight in the Southern Hemisphere's summer, CFCs break down and produce chlorine, which then break apart ozone atoms. But during the winter months (early July to mid-September), the chlorine tends to bind with methane "once all the ozone has been destroyed" in its vicinity, according to the statement. 

"By around mid-October, all the chlorine compounds are conveniently converted into one gas, so by measuring hydrochloric acid, we have a good measurement of the total chlorine," lead study author Susan Strahan, an atmospheric scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, said in the statement.

The MLS instrument observed the ozone hole daily during the Southern Hemisphere's winter. 

"During this period, Antarctic temperatures are always very low, so the rate of ozone destruction depends mostly on how much chlorine there is," Strahan said. "This is when we want to measure ozone loss."

Because previous studies relied on measurements of the physical size of the ozone hole, the authors of the new study say their research is the first to directly show that ozone depletion is decreasing as a direct result of a decrease in the presence of chlorine from CFCs, according to the statement. The 20-percent reduction in depletion is "very close to what our model predicts we should see for this amount of chlorine decline," Strahan said. 

"This gives us confidence that the decrease in ozone depletion through mid-September shown by MLS data is due to declining levels of chlorine coming from CFCs," she said. "But we're not yet seeing a clear decrease in the size of the ozone hole because that's controlled mainly by temperature after mid-September, which varies a lot from year to year."

The study was published Jan. 4 in the journal Geophysical Research Letters.

Follow Calla Cofield @callacofield. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.

A new NASA mission, the first to hitch a ride on a commercial communications satellite, will examine Earth's upper atmosphere to see how the boundary between Earth and space changes over time.

Researchers discussed the new mission, which will launch Jan. 25 from Kourou, French Guiana, attached to the SES-14 communications satellite, in a live video from NASA's Goddard Space Flight Center today (Jan. 4).

GOLD stands for Global-scale Observations of the Limb and Disk, and the mission will focus on the temperature and makeup of Earth's highest atmospheric layers. Along with another upcoming satellite, called ICON, GOLD will examine how weather on Earth — and space weather caused by the sun — affects those uppermost layers. [Earth's Colorful Atmospheric Layers Photographed from Space]

"For years, we've been studying the Earth's upper atmosphere — thermosphere and ionosphere — and we've been looking at those [layers] in detail from the ground and from low-Earth orbit missions," Richard Eastes, the principal investigator for GOLD from the University of Central Florida, said at the NASA presentation. "We wanted to be able to back off [to a higher orbit] and get the big picture, get a whole hemisphere at once. That lets us put things into context that we can't understand when we're just looking at one little piece."

GOLD, which will inspect the ultraviolet radiation that the upper atmosphere releases, will also be the first to take comprehensive records of that atmospheric layer's temperature, Eastes added. The satellite carrying GOLD will orbit 22,000 miles (35,400 kilometers) above Earth in a geostationary orbit, which means GOLD will stay fixed with respect to Earth's surface as the satellite orbits and the world turns. For comparison, the International Space Station cruises at about 250 miles (400 km) above the surface. 

GOLD will pay particularly close attention to Earth's thermosphere, which is the gas that surrounds the Earth higher than 60 miles (97 km) up, and the layer called the ionosphere, which forms as radiation from the sun strips away electrons from particles to create charged ions. And although solar flares and other interactions on the sun do have a strong impact on those layers, scientists are learning that Earth's own weather has an impact on the layers, too.

"In the past, people thought that this region of the Earth's upper atmosphere was affected primarily by what's happening at the sun and what's coming to the Earth from the sun," Sarah Jones, GOLD mission scientist at Goddard, said during the presentation. The sun's radiation and charged particles of solar wind hits Earth's atmosphere, and in response, the planet's magnetic field can cause geomagnetic storms and other space weather. "However, in about the last 10 years or so, there's been this growing body of evidence that the upper atmosphere is also affected by what's going on below.

"For example, tsunamis create waves in the air, and those waves move upwards, and the waves could potentially cause changes even at the very boundary between the Earth and space," she added. "GOLD is studying in particular how to tease out the effects coming from the sun above and Earth below."

Being able to model the region accurately is particularly important, the researchers said, because the ionosphere affects radio and GPS technology as well as spacecraft. Right now, changes can be observed only every several hours, and models of the upper atmosphere can predict only about a day of changes. GOLD will be able to monitor how the upper atmosphere changes and evolves throughout the day on an hourly basis so researchers can build better models.

The ICON (Ionospheric Connection Explorer) spacecraft, which will launch later in 2018, will add another dimension to the understanding researchers gain with GOLD: Rather than taking the far-off view, ICON will fly through the upper atmosphere in low-Earth orbit — 350 miles (560 km) — to get a much closer view of what's going on.

"The cool thing about the combo between ICON and GOLD is the fact that we're getting this global view that's actually remote sensing, and then we have the in situ view, [where] we're actually sending something through it," Alex Young, the associate director for heliophysics science at Goddard, said during the presentation. Using the two together, researchers can pin down exactly what causes changes to the boundary between Earth and space, to better understand the impact it will have below — and above, Young said.

"Not only is it telling us about fundamental science, which is pertinent not just to what happens here in our solar system, but in fact in other solar systems, exoplanet systems — but also, all of this energy and matter interacts with our technology," Young said. "It's interacting with spacecraft, sometimes disrupting them, and it even creates a really nasty environment for astronauts. Understanding that is important also for space travel near the Earth and through the rest of the solar system."

Email Sarah Lewin at slewin@space.com or follow her @SarahExplains. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com. 

When the moon's shadow zipped across the United States during the Great American Solar Eclipse this past August, the shadow traveled so fast it created waves in Earth's upper atmosphere, a new study finds.

During a solar eclipse, the moon passes between the sun and Earth, casting its shadow in a narrow path across parts of the planet. Since the 1970s, researchers have suspected that the moon's shadow, which travels at supersonic speeds during a solar eclipse, could create waves in the ionosphere— a part of Earth's upper atmosphere that has electronically charged particles.

But they hadn't been able to prove it until now, the researchers told Live Science. [Photos: 2017 Great American Solar Eclipse]

Bow waves

Researchers suspected that the moon's shadow could "make waves" because whenthe moon travels between the sun and Earth, its shadow blocks the sun's energy, rapidly cooling the area beneath it. But because the shadow moves so quickly, anything in its wake is swiftly reheated. This sudden temperature change was thought to generate waves in "the atmosphere at altitudes where the ozone layer and water vapor efficiently convert solar [ultraviolet] radiation to heat," the researchers wrote in the study.

"The August eclipse provided a great opportunity to examine this," said study lead researcher Shun-Rong Zhang, a research scientist at the Massachusetts Institute of Technology's Haystack Observatory.

To investigate, Zhang and his colleagues used a dense network of about 2,000 sensors across North America that were receiving signals from satellites, known as the global navigation satellite system (GNSS). There were GNSS sensors "in the entire eclipse totality," and in affected regions over the entire continental U.S., Zhang told Live Science in an email.

These sensors can take incredibly accurate measurements. By analyzing data collected by the sensors, researchers can determine the total electron content (TEC) in the column stretching from the sensors to the satellites, which are located about 12,000 miles (20,000 kilometers) above Earth. These sensors can measure differentials in TEC, allowing the scientists to "detect very fine ionospheric disturbances," Zhang said.

During the total solar eclipse on Aug. 21, the sensors collected data on electron movement in the upper atmosphere. In effect, they were looking for bow waves — just like the waves that form in the water at the bow, or front, of a moving ship. The outer limit of the impact region can have a bow-shaped front shock, Zhang said.

The researchers also looked for stern waves, named after the rear part of a boat that also makes waves as it moves through water. "Similar bow waves, including stern waves, occur also when airplanes travel through the air at the speed of sound," said Zhang, who worked with his colleagues at Haystack Observatory and the University of Tromso, in Norway, to do this study.

Their analysis revealed that the moon's shadow created bow waves with front shocks, as well as stern waves, he said. The waves were large — at least 10 degrees longitude by 10 degrees latitude.

They moved mostly along the path of totality at almost 670 mph (300 meters per second), and lasted for about 1 hour, Zhang added.

These waves aren't dangerous, he noted. "It is an object of mainly scientific interests," Zhang said.

Previously, a 2011 study claimed to have detected 55 bow waves and stern waves, but this was based on limited coverage over East Asia during an eclipse on July 22, 2009, the researchers noted.

The story was published online Dec. 4 in the journal Geophysical Research Letters.

Original article on Live Science.

A NASA sounding rocket launched early this morning and lit up the skies over the U.S. East Coast with colorful clouds, ringing in an early July Fourth celebration.

The launch of the Terrier-Improved Malemute two-stage sounding rocket had been repeatedly rescheduled, but the rocket finally got its chance at 4:25 a.m. EDT (0825 GMT) today (June 29). The rocket lifted off from NASA's Wallops Flight Facility in Virginia, and its flight lasted about 8 minutes.

About 4 to 6 minutes into takeoff, 10 canisters released barium, strontium and cupric oxide, which interacted with each other to form colorful vapor. Scientists could use the red and blue-green artificial clouds that formed to track the movement of particles in Earth's ionosphere, which is in its upper atmosphere. They were visible along the mid-Atlantic coastline from North Carolina as far north as New York, and could be seen as far west as Charlottesville, Virginia, according to NASA. (NASA Wallops reported cloud views as far as Staten Island, NY and Outer Banks, NC.)

"Two-stage" refers to the method of rocket launch where the first stage achieves liftoff from Earth's surface, and those propellants are discarded soon after to reduce the weight of the rocket. At that moment, the second, upper stage fires to continue the journey. The word "sounding" is a borrowed nautical term meaning the rocket is intended to take measurements.

The ionosphere that the sounding rocket is looking to study is the layer of Earth's atmosphere that is ionized (hence the name) by solar and cosmic radiation. When an atom or molecule is called an ion, it simply means that the particle does not have the normal number of electrons — instead, it carries a negative or positive charge.

Editor's note: If you caught an amazing photo of the launch or artificial clouds and you'd like to share it with us and our partners for a story or image gallery, send images and comments in to managing editor Tariq Malik at spacephotos@space.com.

Follow Doris Elin Salazar on Twitter @salazar_elin. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com. 

In what appears to be a historic first, a fast-food chicken sandwich was successfully carried to the edge of space today aboard a high-altitude balloon.

The Kentucky Fried Chicken Zinger sandwich journeyed skyward aboard a World View Enterprises Stratollite balloon vehicle at 9:11 a.m. EDT (1311 GMT) from Spaceport Tucson in Arizona. While the live webcast cut out before liftoff, a representative for World View confirmed that the launch was successful, and KFC later released a video of the balloon taking off.

"Holy cow, that's some spicy, crispy chicken moving out at an average rate of 1,000 feet per minute [304 meters per minute]," the announcer in the KFC video said as the balloon lofted skyward. "The Zinger should arrive at target altitude in about 1 hour and 20 minutes, where the Zinger mission will officially begin."

The sandwich is scheduled to remain aloft for four days and maintain an altitude of about 50,000 to 80,000 feet (15,200 to 24,400 meters). During the flight, which is serving as an advertising campaign for Kentucky Fried Chicken (KFC), the company will execute various activities to engage the public over social media, including a coupon drop, in which a coupon will literally be dropped from the balloon down to Earth. 

"The team on the ground here is justifiably celebrating as they watch their months of hard work pay off," the video announcer said. "This is the greatest achievement in chicken sandwich space travel history. In all my years in this business I've certainly never seen anything like it. What a time to be alive."

The Zinger-1 mission will serve as a test flight for World View, which aims to make stratospheric balloons that can remain in flight for months at a time. The flight is scheduled to be the first "extended-duration development flight of [World View's] high-altitude Stratollite vehicle," according to a statement from the company.

World View's high-altitude balloons are designed to operate in a region of the atmosphere that is too high for most commercial airliners, but too low for satellites. The Stratollite vehicles are expected to be able to reach altitudes of up to 28.5 miles or about 150,000 feet (45.8 kilometers), which means they would remain below the Karman line; at 62 miles (100 km) above the Earth, this line is considered the boundary of "space."

The company has said it plans to use these balloons for scientific endeavors such as Earth imaging, weather monitoring and even astronomical observations. In addition, World View has announced plans to make balloons that can carry humans into the stratosphere as part of scientific missions or for near-space tourism.

While neither KFC nor World View has said exactly how much KFC paid for the flight, World View representatives said that the advertising campaign covered most of the cost of the test flight.

The launch was originally scheduled for June 21, but was delayed due to weather.

Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.

A small NASA rocket will launch to create colorful artificial clouds tonight (June 12), and you can watch all the action live. Weather permitting, the launch could be visible to spectators on the U.S. East Coast from New York to North Carolina, NASA officials said.

The two-stage Terrier-Improved Malemute sounding rocket is scheduled to lift off from NASA's Wallops Flight Facility in Virginia tonight between 9:04 p.m. EDT and 9:19 p.m. EDT (0104-0119 GMT). NASA's live webcast will begin at 8:30 p.m. EDT (0030 GMT). You can also watch it live on Space.com, courtesy of NASA. 

About 5 minutes after liftoff, the rocket will deploy 10 soft-drink-size canisters, which will release barium, strontium and cupric-oxide vapor to form blue-green and red artificial clouds.

"These clouds, or vapor tracers, allow scientists on the ground to visually track particle motions in space," NASA officials wrote in a mission update. "The clouds may be visible along the mid-Atlantic coastline from New York to North Carolina."

If you live near the Wallops Island area in Virginia and would like to watch the sounding rocket launch in person, NASA's Wallops Flight Facility Visitors Center will open to the public at 8 p.m. EDT. Because the launch is weather dependent, local spectactors and online viewers can receive the latest updates from NASA via the Wallops center Facebook and Twitter sites.

The mission is designed to test a new multicanister ejection system that should allow researchers to gather data over a wider area than has been possible, agency officials added.

The rocket's total flight time will be about 8 minutes. The mission's main payload will hit the Atlantic Ocean about 90 miles (145 kilometers) off the Virginia coast and will not be recovered, NASA officials said.

The mission was originally supposed to lift off late last month, but it has been delayed several times by weather and once by a boat straying into the launch zone.

Editor's note: If you capture an amazing image of the sounding rocket launch or the colorful artificial clouds that you would like to share with Space.com and its news partners for a story or photo gallery, send photos and comments to: spacephotos@space.com.

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on Space.com.

One of the still-unsolved mysteries about Earth's history is how the planet became oxygenated, and breathable, billions of years ago. Now, a new study says the culprit may have been the giant rock slabs that make up the Earth's outer shell.

As these so-called plates moved, in a process called plate tectonics, they would have buried carbon-rich remains of dead creatures beneath other plates as they slid underneath. In the Earth's mantle, under the crust, the carbon wouldn't be able to react with oxygen, leaving this vital ingredient in the atmosphere, the scientists said.

Until the Great Oxygenation Event, the planet's atmosphere was a mix of nitrogen, carbon dioxide, water vapor and methane. Then, 2.5 billion years ago, a class of single-celled creatures started using that carbon dioxide and producing oxygen as a waste product. But oxygen is highly reactive; reactions with surface rocks and carbon seeping from the remains of dead organisms would quickly deplete the element. 

Related: New Way to Make Oxygen Doesn't Need Plants

Burying carbon

The new study by Megan Duncan and Rajdeep Dasgupta at Rice University in Texas posited that the carbon from the dead creatures got pushed under the Earth's crust, or subducted, to form graphites and ancient diamonds. As such, the duo said, the Great Oxygenation Event was, in part, driven by the start of "modern" plate tectonics, in which the Earth's crust is divided into huge plates that collide, jostle, and slide over and under one another.

The process was efficient enough that the carbon didn't have time to react with the oxygen, so the oxygen — the waste product of all those early creatures — stayed in the atmosphere and accumulated to near the levels seen today. The result: an atmosphere amenable to future oxygen-breathers. [Photo Timeline: How the Earth Formed]

"This work started by considering processes that happen in subduction zones today," Duncan told Live Science. "And then [we continued by] wondering what happened in the ancient subduction zones."

Duncan used a computer model of the atmosphere showing a reaction between carbon dioxide and water. When the two react, they make molecular oxygen (made up of two oxygen atoms) and formaldehyde (a compound made up of carbon, hydrogen and oxygen). The formaldehyde isn't necessarily what living creatures would actually produce; it's a stand-in for more complex organic carbon compounds, Duncan said.

Ordinarily, that reaction is balanced; the oxygen cycles back to make more carbon dioxide (CO2) and water, leaving an atmosphere devoid of oxygen. That's where the plate tectonics come in, the researchers said. According to the new study, the jostling plates pushed all the formaldehyde underground, leaving the air with more oxygen. Meanwhile, without the formaldehyde driving the "balanced" chemical reaction, extra CO2 would remain in the atmosphere, helping the CO2-breathers to thrive and produce even more oxygen as waste, the researchers found in their computer model.

Keeping carbon in check

To check their hypothesis, the researchers used both older measurements of carbon in the ancient crust and lab experiments. In some ancient diamonds, for example, there's a certain amount of carbon-13, a carbon isotope found in tissues of living organisms. That data showed that some amount of organic carbon clearly made it into the mantle (beneath Earth's crust), the researchers said.

The next question was whether the carbon would stay there. Duncan melted a piece of silicate glass and added graphite to it. The glass simulated the ancient crust, and the graphite represented the carbon from organisms, Duncan said. She then increased the pressure and temperature, starting at some 14,800 atmospheres of pressure and increasing it to 29,000 atmospheres (that's some 435,000 pounds per square inch). The results showed that carbon could dissolve in rock under the conditions likely present in early Earth's mantle, the study said. The result also showed that the carbon was likely to stay under the crust for millions of years before volcanoes burped it out again, the study said.

Pinning down the exact mechanism for the Great Oxygenation Event isn't going to be easy, Duncan said, and likely it involved several mechanisms, not just one. One challenge is the timeline of when subduction started, she said.

"If the modern plate tectonic processes have always been in action, this doesn't work," Duncan said. Other lines of evidence seem to show that early Earth might not have had plate tectonics initially and that the process started later, Duncan added.

"It also depends on how much organic carbon was removed from the surface," Duncan wrote in an email. "How much organic carbon made it to the ocean floor (which likely depends on ancient ocean chemistry). We know it happens today. We can go out and measure it. We see it in ancient rocks, and potentially in the diamonds, so we believe that organic carbon was present and subducted throughout Earth's history."

The problem is putting exact limits on how much and how fast, she said.

Tim Lyons, a professor of biogeochemistry at the University of California Riverside, agreed that linking this model to the known record in rocks is a challenge. "One of my questions is whether those data can be tied to a robust record for the history of subduction," Lyons said.

"There have been many mechanisms proposed to cause the GOE [Great Oxygenation Event]; none, on their own, can re-create the magnitude of O2 [oxygen] increase that is observed from the record," Duncan said. "It was likely a combination of many of these mechanisms, including subduction, that allowed O2 levels to rise and be maintained for the rest of Earth's history."  

The study appeared (April 25) in the journal Nature Geoscience.

Original article on Live Science.

In an unexpected first, researchers have discovered ammonia in Earth's lowest atmospheric layer, a new study said.

The detected ammonia was most concentrated in the upper layer of the troposphere above India and China, countries that have experienced population and economic booms in recent years. The gas (NH3) is most likely coming from livestock farming and fertilization in those countries, the researchers said.

Plants and crops need ammonia to grow, but too much of it can harm the environment and human health. However, the newly detected ammonia may have an unexpected silver lining: The gas is involved in cloud formation, so it may act as a cooling agent and help compensate for the human-caused greenhouse gas effect, the researchers said. [Infographic: Earth's Atmosphere Top to Bottom]

Now that researchers are aware of the ammonia, they can incorporate it into models assessing and predicting climate change, the researchers added.

The troposphere

The troposphere reaches from 4 miles to 12 miles (7 to 20 kilometers) above sea level and includes up to 80 percent of Earth's atmosphere and weather phenomena.

During an investigation, a team of researchers from Germany, Colorado and Mexico collected satellite data from different regions of the upper troposphere between June 2002 and April 2012, and calculated the three-month averages of ammonia concentrations.

Surprisingly, they found atmospheric ammonia about 7.5 miles to 9.3 miles (12 to 15 km) above sea level in the same area and time period in which Asian summer monsoons happen. In this region — above north India and southeast China — the ammonia had a concentration of 33 pptv (33 ammonia molecules per trillion air molecules), the researchers found.

A thorough search failed to reveal ammonia at these levels during any other season or anywhere else on Earth, the scientists said.

"We have presented the first evidence of ammonia being present in Earth's upper troposphereabove 10 km [6.2 miles]," the researchers wrote in the study.

The discovery indicates that agricultural ammonia produced on Earth's surface can make its way into the troposphere, where it ends up in monsoons, the researchers said.

"Observations show that ammonia is not washed out completely when air ascends in monsoon circulation," the study's lead researcher, Michael Höpfner, the head of the Remote Sensing Using Aircraft and Balloons Group at the Institute of Meteorology and Climate Research at the Karlsruhe Institute of Technology in Germany, said in a statement. "Hence, it enters the upper troposphere from the boundary layer close to the ground, where the gas occurs at relatively high concentrations."

Cloud formation

Ammonia can act as an aerosol, or teensy particles suspended in the atmosphere. Aerosols often act as "cloud seeds" around which cloud droplets can form.  

Aerosols are the smallest particles known to contribute to cloud formation, and they also appear to influence the properties of existing clouds, the researchers said. For instance, aerosols can alter the size of cloud particles, changing how clouds reflect and absorb sunlight. This can lead to reduced visibility (haze) and redder sunrises and sunsets, according to NASA.

The finding shows that in addition to polluting local ecosystems, agricultural ammonia released in high concentrations can drive the formation of new clouds and alter the properties of existing clouds, the researchers said. [Gallery: Reading the Clouds]

In a strange twist, humans may rely on atmospheric ammonia to mitigate the human-induced effects of climate change. The accumulation of aerosols in the troposphere is thought to have a cooling effect, as clouds reflect the sun's energy. However, clouds can also trap heat released by Earth, which can warm the planet.

In a November study published in the journal Nature Communications, researchers found that ammonia released from guano (seabird poop) in the Arctic may influence cloud formation, leading to a slight cooling effect there.

The new study was published online Nov. 18 in the journal Atmospheric Chemistry and Physics.

Original article on Live Science.

Atmospheric oxygen levels have declined over the past 1 million years, although not nearly enough to trigger any major problems for life on Earth, a new study finds.

The research behind this new finding could help shed light on what controls atmospheric oxygen levels over long spans of time, the researchers said.

Atmospheric oxygen levels are fundamentally linked to the evolution of life on Earth, as well as changes in geochemical cycles related to climate variations. As such, scientists have long sought to reconstruct how atmospheric oxygen levels fluctuated in the past, and what might control these shifts. 

Related: New Way to Make Oxygen Doesn't Need Plants

However, models of past atmospheric oxygen levels often markedly disagree, differing by as much as about 20 percent of Earth's atmosphere, which is oxygen's present-day concentration, the researchers said. 1 It is not even known if atmospheric oxygen levels varied or remained steady over the past 1 million years.

"There was no consensus on whether the oxygen cycle before humankind began burning fossil fuels was in or out of balance and, if so, whether it was increasing or decreasing," said study lead author Daniel Stolper, a geochemistat Princeton University in New Jersey.

In the new study, researchers calculated past atmospheric oxygen levels by looking at air trapped inside ancient polar ice samples. Specifically, they looked at samples from Greenland and Antarctica.

The new estimates suggest that atmospheric oxygen levels have fallen by 0.7 percent over the past 800,000 years. The scientists concluded that oxygen sinks — processes that removed oxygen from the air — were about 1.7 percent larger than oxygen sources during this time.

Although a drop in atmospheric oxygen levels might sound alarming, the decrease the researchers found "is trivial in regard to ecosystems," Stolper told Live Science. "To put it in perspective, the pressure in the atmosphere declines with elevation. A 0.7 percent decline in the atmospheric pressure of oxygen occurs at about 100 meters (330 feet) above sea level — that is, about the 30th floor of a tall building."

There are two hypotheses that may help explain this oxygen decline over the past million years, Stolper said.

"The first is that global erosion rates may have increased over the past few to tens of millions of years due to, among other things, the growth of glaciers — glaciers grind rock, thereby increasing erosion rates," Stolper said.

Rising erosion rates would have exposed more pyrite and organic carbon to the atmosphere. Pyrite is better known as fool's gold, and organic carbon consists of the remains of organisms, mostly land plants and aquatic photosynthetic microorganisms such as algae. Previous research found that both pyrite and organic carbon can react with oxygen and remove it from the atmosphere. [Infographic: Earth's Atmosphere Top to Bottom]

"Alternatively, when the ocean cools, as it has done over the past 15 million years, before fossil fuel burning, the solubility of oxygen in the ocean increases. That is, the oceans can store more oxygen at colder temperatures for a given concentration of oxygen in the atmosphere," Stolper said. Oxygen-dependent microbes in the ocean and in sediments can then become more active and consume this oxygen, leaving less of the element in the atmosphere, he added.

Future research can identify what geological processes are consistent with these findings "and thus help to identify the major processes that control atmospheric oxygen levels," Stolper said.

These findings also reveal what might be a strange contradiction, because it could be assumed that atmospheric carbon dioxide levels should rise as oxygen levels fall — "for example, right now we are consuming oxygen and breathing out carbon dioxide," said study senior author John Higgins, a geochemistat Princeton.

However, previous research has found that atmospheric carbon dioxide levels have not, on average, changed over the past 800,000 years, Higgins noted. "At first glance, these two sets of observations, both from gases trapped in ice cores, are paradoxical," he said.

One way out of this conundrum is a well-known but relatively untested concept that suggests "that on timescales longer than a few hundred thousand years, atmospheric carbon dioxide and Earth's temperature are regulated via a 'silicate weathering thermostat,'" Higgins said.

Basically, increasing atmospheric carbon dioxide levels will boost the rates at which volcanic rocks wear down and their components wash into the seas, which can then go on to trap atmospheric carbon dioxide in ocean minerals. This means that "one can have a change in atmospheric oxygen with no observable change in average carbon dioxide," Higgins said. "Importantly, this silicate weathering thermostat is one reason why Earth is thought to have remained habitable for billions of years despite changes in solar luminosity."

The scientists detailed their findings online today (Sept. 22) in the journal Science.

Original article on Live Science.

More than 50 years after weird radio echoes were detected coming from Earth's upper atmosphere, two scientists say they've pinpointed the culprit. And it's complicated.

In 1962, after the Jicamarca Radio Observatory was built near Lima, Peru, some unexplainable phenomenon was reflecting the radio waves broadcast by the observatory back to the ground to be picked up by its detectors. The mysterious cause of these echoes was sitting at an altitude of between 80 and 100 miles (130 and 160 kilometers) above sea level. 

"As soon as they turned this radar on, they saw this thing," study researcher Meers Oppenheim, of the Center for Space Physics at Boston University, said, referring to the anomalous echo. "They saw all sorts of interesting phenomena that had never been seen before. Almost all of it was explained within a few years." [In Photos: Mysterious Radar Blob Puzzles Meteorologists]

Peculiar radar echoes

Though the other phenomena detected by the observatory got explanations, these radar echoes continued to baffle scientists.

To see what was happening at that altitude, researchers at the time sent rockets, equipped with antennas and particle detectors, through the region. The instruments, which were designed to detect radar waves, "saw almost nothing," Oppenheim said.

Adding more peculiarity to the puzzle, the phenomenon showed up only during daylight hours, vanishing at night. The echo would appear at dawn every day at about 100 miles (160 km) above the ground, before descending to about 80 miles (130 km) and getting stronger. Then at Noon, the echo would start to rise back again toward its starting point at 100 miles above the ground. When plotted on a graph, the echoes appeared as a necklace shape.

And in 2011, during a partial solar eclipse seen over the National Atmospheric Research Laboratory in India, the echo went silent.

"And then there was a solar flare, and it sort of went a little nuts," Oppenheim said. "There was a solar flare, and the echo got really strong."

The sun takes charge

Now, with a lot of supercomputing effort, Oppenheim and Yakov Dimant, also at the Center for Space Physics, have simulated the bizarre radar echoes to find the culprit — the sun. [Infographic: Explore Earth's Atmosphere, Top to Bottom]

Ultraviolet radiation from the sun, it seems, slams into the ionosphere (the part of Earth's upper atmosphere located between 50 and 370 miles, or 80 and 600 km, above sea level), where the radio echoes were detected, they said. Then, the radiation, in the form of photons (particles of light), strips molecules in that part of the atmosphere of their electrons, resulting in charged particles called ions — primarily, positively charged of their electrons, resulting in charged particles called ions, primarily positively charged oxygen — and a free electron (a negatively charged particle that is not attached to an atom or molecule).

That ultra-energized electron, or photoelectron, zips through the atmosphere, which, at this altitude, is much cooler than the photoelectron, Oppenheim said.

Making waves

Using a computer simulation, the scientists allowed these high-energy electrons to interact with other, less energized particles.

Because these high-energy electrons are racing through a cool, slow environment in the ionosphere, so-called kinetic plasma instabilities (turbulence, in a sense) occur. The result: The electrons start vibrating with different wavelengths.

"One population of very energetic particles moving through a population of much less energetic particles — it's like running a violin bow across the strings. The cold population will start developing resonant waves," Oppenheim explained.

"The next step is that those electron waves have to cause the ions to start forming waves too, and they do," Oppenheim said.

Though this last step isn't clearly understood, he explained that periodic waves of ions bunch up with no dominant wavelength winning out. "It's a whole set of wavelengths; it's a whole froth of wavelengths," he said.

That "froth" of wavelengths was strong enough to reflect radio waves back to the ground and to form the mysterious radar echoes.

"The reason it wasn't figured out for a long time is that it's a complicated mechanism," Oppenheim said.

As for why the rockets missed the bizarre echoes, Oppenheim pointed to the messy nature of the waves.

"Turns out, it looks like what the rockets saw is what we see with our simulation," he said. "You don't see strong coherent waves. What you see is sort of a froth of low-level waves, above the noise of thermal material," and those waves are sort of like "foam on the top of sea waves," he added.

Follow us @livescience, Facebook & Google+. Original article on Live Science.

The oldest space dust yet found on Earth suggests that the ancient atmosphere of Earth had significantly more oxygen than previously thought, a new study finds.

Although oxygen gas currently makes up about one-fifth of Earth's air, there was at least 100,000 times less oxygen in the primordial atmosphere, researchers say. Oxygen easily reacts with other molecules, which means it readily gets bound to other elements and pulled from the atmosphere.

Previous research suggests that significant levels of oxygen gas started permanently building up in the atmosphere with the Great Oxidation Event, which occurred about 2.4 billion years ago. This event was most likely caused by cyanobacteria — microbes that, like plants, photosynthesize and release oxygen. [Infographic: Earth's Atmosphere Top to Bottom]

Most evidence regarding how much oxygen there was in Earth's air in the past concerned the lower atmosphere. Until now, scientists had no way to sample oxygen levels in Earth's ancient upper atmosphere.

In a new study, scientists analyzing tiny meteorites found that the upper reaches of the early Earth's atmosphere may not have been oxygen-poor as once thought. Instead, the ancient Earth's upper atmosphere may have possessed nearly the same amount of oxygen as it does today, the researchers said.

"With this project we have opened up a new way of investigating Earth's ancient atmosphere," said study lead author Andrew Tomkins, a geoscientist at Monash University in Melbourne, Australia.

Space dust

The researchers analyzed 60 microscopic meteorites from samples of ancient limestone collected in the Pilbara region in Western Australia. These cosmic dust particles are 2.7 billion years old, the oldest yet found.

"We weren't certain that the project was going to work," Tomkins told Live Science. "The project started out as a student research project, and it was a bit of a risk to try and find micrometeorites when few other people had tried it before. I had some backup plans, but the extra tension made for a lot of excitement when we found our first micrometeorites."

The micrometeorites ranged from two to 12 times thinner than the width of an average human hair. They are cosmic spherules — remnants of meteorites the size of sand grains that broke apart during atmospheric entry. Previous research suggested that these kinds of particles melt at altitudes of about 45 to 55 miles (75 to 90 kilometers).

The scientists analyzed the micrometeorites using electron microscopes and high-energy X-rays from the Australian Synchrotron. They found that a significant portion of the iron in these meteorites had reacted with oxygen to form iron oxide minerals, which suggests that the thin upper atmosphere in which they melted was richer in oxygen than thought.

"Once we recovered the first micrometeorites, I realized that the minerals inside them were telling us that they had been oxidized in the upper atmosphere," Tomkins said. "These were essentially the first samples of our Earth's ancient upper atmosphere." [Fallen Stars: A Gallery of Famous Meteorites]

This finding was unexpected, "because it has been firmly established that the Earth's lower atmosphere was very poor in oxygen 2.7 billion years ago," study co-author Matthew Genge, a professor in the Department of Earth Science & Engineering at Imperial College London, said in a statement. "How the upper atmosphere could contain so much oxygen before the appearance of photosynthetic organisms was a real puzzle."

What could have happened?

One possible origin of this oxygen is that sunlight broke apart water vapor in the lower atmosphere into hydrogen and oxygen — the oxygen could have risen to the upper atmosphere, while the lighter hydrogen would have escaped Earth's atmosphere into outer space. Another possibility is that sunlight broke apart sulfur dioxide gas emitted from volcanoes into sulfur and oxygen — the sulfur could have condensed to form particles that fell to Earth, leaving oxygen behind, the researchers said.

"A caution — it's important to understand that the density of the atmosphere at the very high altitudes sampled by micrometeorites is extremely thin," Tomkins said. "We are not talking about generating large amounts of oxygen here, but rather elevated proportions of oxygen relative to the other gases."

It remains uncertain how the ancient upper atmosphere could have stayed oxygen-rich while the ancient lower atmosphere remained oxygen-poor. The researchers suggest that a methane haze layer may have existed between the upper and lower atmosphere, reducing mixing between them.

"Methane is thought to have been produced by early single-celled organisms known as methanogens. These exist today as well," Tomkins said. "There has been a lot of debate as to how much methane there might have been, and when it might have first arisen. The general thought is that the methane, combined with carbon dioxide, may have created an organic haze if the conditions were right."

The next step "is to try and extract micrometeorites from rocks of a range of ages, to examine how the chemistry of Earth's upper atmosphere might have changed over very long periods of geological time," Tomkins said. "It should be possible to use micrometeorites to investigate changes in atmospheric composition across very broad periods of time."

"It should also be possible to find micrometeorites on Mars," Tomkins added. "If the rovers can find them, and somehow determine their age of atmospheric entry, they could be used to investigate changes in Mars' atmosphere."

The scientists detailed their findings in the May 12 issue of the journal Nature.

Follow us @livescience, Facebook & Google+. Original article on Live Science.

Scientists may have finally found the cause of a mysterious disappearance of electrons dozens of miles above Earth.

It turns out that a layer of invisible meteor dust falling to Earth every day may be sucking up electrons coming from higher in the atmosphere, creating the so-called "D-region ledge," where the concentration of electrons suddenly plunges, Earle Williams, an atmospheric electrician at the Massachusetts Institute of Technology, said earlier this month at the annual meeting of the American Geophysical Union.

Physicists have long been hunting for the disappearing electrons, and had turned to everything from high-flying ice clouds to electrically charged water clusters in the atmosphere to explain the sudden drop-off in this region, he said. [Infographic: Earth's Atmosphere Top to Bottom]

"It's the most dramatic gradient anywhere in the ionosphere," Williams said, referring to the part of Earth's upper atmosphere where the D-region ledge is found. "It really is very conspicuous, so it's begging for an explanation."

The case of the disappearing electrons

Far above Earth's surface, ultraviolet rays from the sun interact with nitric oxide in the atmosphere to produce electrons that travel toward Earth. But since the 1960s, scientists have known that there is an sharp drop in the number of electrons present in the atmosphere at night. This drop was found when rockets first breached the upper atmosphere to sample its temperature, pressure and electron density. This "electron ledge" occurs within the ionosphere's D-layer, which stretches between 37 miles and 56 miles (60 km and 90 km) above the Earth's surface.

The D-region ledge plays a critical role in modern communication. The planet itself conducts electricity, as does the layer of the ionosphere above the ledge, but electromagnetic waves don't travel through nonconductive materials, like the electron-depleted region below the ledge. Below the ledge, the electron-depleted air acts as an insulator, forming a layer between the Earth and its atmosphere that enables radio waves and very low frequency electromagnetic waves to circle the globe. [Quiz: The Science of Electricity]

The D-region ledge appears most strongly at night and shows up equally in the atmosphere above the poles, the equator and everywhere in between. Yet no one knew why it was there.

Exhausting the possibilities

In the new study, Williams and his colleague, Joanne Wu, a doctoral candidate at the National Cheng Kung University in Taiwan, say that they and other colleagues had looked at many of the prevailing hypotheses to explain the ledge and found most lacking. For instance, some researchers had proposed that ice clouds could be absorbing the free electrons. But ice clouds tend to clump closer to Earth's high latitudes, whereas the D-region ledge is equally prominent everywhere from the poles to the equator.

Then they came upon a 1980 paper in the Journal of the Atmospheric Sciences, which suggested that another layer of the atmosphere, called the sodium layer, could be attributed to fine dust from meteoroids. In that explanation, as space rocks travel through the thin upper atmosphere, they jostle nitrogen and oxygen molecules, heating up in the process. As they fall farther, they collide with more atoms in the more densely packed atmosphere, becoming hot enough to boil, at which point individual sodium atoms peel off from the meteoroid.

That made the team wonder: Could the heating of tiny meteors also explain the D-region ledge?

Electron sink

In this new theory, minerals such as iron and silicon, which make up a much greater part of meteoroids than sodium, would also boil off the meteoroid, forming a cloud of smoke and dust. Free-floating silicon and iron atoms would then smash into oxygen and nitrogen in the atmosphere, knocking free electrons in the iron and silicon atoms' outer electron shells. The electrons from the meteor boiling would then transform into faint glimmers of light too small to see with the naked eye.

Meanwhile, the meteor dust itself would bind to the free electrons that were formed when the sun's ultraviolent rays interacted with the atmosphere. The reason the D-region ledge is so prominent at night is because ultraviolet radiation from the sun during the day is 100 times greater than at night, so the production of free electrons dwarfs the ledge effect during the day.

If the theory is right, then "you'll form a thick zone of dust descending very slowly due to gravity," Williams said. "Eventually all this dust comes to the Earth's surface. It's about 100 tons per day worldwide," but we can't easily detect it because the tiny particles are so small.

Lots of small rocks

But why does this ledge occur 53 miles (85 km) above Earth? In the researchers' theory, the meteoroids at this height are mostly the right size and are traveling at the right speeds to burn up at that height in the atmosphere. The meteors that could explain the ledge would need to be small: roughly about 10 micrograms. And they would need to be "slow," traveling about 29,000 to 33,500 miles per hour (13 to 15 km/s) — just above the escape velocity of Earth, Williams said.

There may be plenty of these small, slow meteors. Both radars, which show little pings of electricity when teensy meteoroids burn up in the atmosphere, as well as a few satellites, which have been pockmarked by the barrage of myriad tiny meteoroids, suggested that the vast majority of space rocks that bombard the Earth every day are these small, unimpressive specimens. Though they don't leave a stunning light trail like so-called shooting stars, small meteors could be a thousandfold more numerous than the cosmic debris that lights up the night sky, Williams said.  

"It's a very plausible idea," said Morris Cohen, an ionospheric physicist at the Georgia Institute of Technology in Atlanta, who was not involved in the study. "There's a lot of circumstantial theory to back up to the idea, it's all consistent."

However, it will be tough to test the idea directly, as that region of the atmosphere is so inaccessible, Cohen said.

"It's too high to reach with balloons, and it's too low to hit with satellites," Cohen told Live Science.

The D-region ledge is not the only strange boundary in that portion of the atmosphere — the region between 50 and 62 miles (80 and 100 km) above the surface also has an "airglow" layer, caused by the sharp rise in the ionization of hydroxyl, as well as multiple sodium layers, said Steven Cummer, an electrical engineer at Duke University in North Carolina, who was not involved in the study. 

"This region is so hard to measure that little work has been done to see if these boundaries are connected," Cummer told Live Science in an email. "But the idea that a fundamental feature of Earth's atmosphere is created by the continual deposition of material by meteors is pretty exciting."

Follow Tia Ghose on Twitterand Google+. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

Earth's magnetic field, which protects the planet from harmful blasts of solar radiation, is much older than scientists had previously thought, researchers say. In fact, this invisible, protective shield likely existed shortly after the planet formed — a finding that could shed light on why Earth is habitable and Mars is not.

Without Earth's magnetic field, solar winds — streams of electrically charged particles that flow from the sun — would strip away the planet's atmosphere and oceans. As such, Earth's magnetic field helped to make life on the planet possible, researchers have said.

The magnetic field is generated by swirling liquid metal in Earth's outer core, and this "geodynamo" requires the release of heat from the planet to drive its churning. Nowadays, this heat flow is aided by plate tectonics — the movement of the plates of rock that make up the planet's exterior — which efficiently lets heat transfer from Earth's interior to its surface. [50 Amazing Facts About Planet Earth]

Given the importance of Earth's magnetic field, scientists want to pinpoint when it first developed, which could, in turn, provide clues about how the planet has been able to remain habitable and when plate tectonics began. However, when, exactly, plate tectonics originated is hotly debated, and some researchers argue that the early Earth lacked a magnetic field.

Since 2010, the best estimate of the age of Earth's magnetic field was 3.45 billion years. In comparison, Earth is about 4.6 billion years old.

Now, scientists have found that Earth's magnetic field could be up to 4.2 billion years old — about 750 million years older than had been previously thought.

The researchers investigated magnetically sensitive minerals such as magnetite, a naturally occurring cousin of rust. As molten rock cools, magnetite within it becomes literally set in stone, pointing to the location of Earth's magnetic poles at the moment it froze. As a result, the oldest samples of magnetite can reveal the direction and intensity of Earth's magnetic field at the earliest parts of Earth's history, the researchers said.

The scientists analyzed magnetite samples trapped in tiny, ancient zircon crystals that were collected from the Jack Hills in Western Australia. To detect the magnetic fields, the scientists had to have a special magnetic sensor built that was 10 times more sensitive than other instruments used to make these kinds of measurements.

Isolating the zircons from the surrounding rock was challenging. "Typically, we separate zircons out using high magnetic fields, but we couldn't do that here, since it would destroy what information they had," said John Tarduno, a geophysicist at the University of Rochester in New York and lead author of the new study detailing the findings. "So we had to separate thousands of zircons out by hand, cleaning them in mild acids, which took a huge amount of time," Tarduno told Live Science.

Then, to get reliable measurements, the researchers had to make sure the samples they analyzed never got hot enough after they formed to allow the magnetic information recorded within to reset. The researchers found that the minerals were pointed in a variety of magnetic directions, which suggested the samples were pristine.

"[I]f the magnetic information in the zircons had been erased and re-recorded, the magnetic directions would have all been identical," Tarduno said in a statement.

The intensity of the magnetic fields that the samples recorded suggests the presence of an ancient geodynamo, the researchers said.

These findings likely indicate that Earth had a magnetic field, and plate tectonics, since very early in its history.

"It's surprising, because some of the models of the ancient Earth suggest that a magnetic field or plate tectonics could not have occurred that early," Tarduno said. "Those models need to be rethought to include potential ways of cooling Earth's interior early on."

This ancient magnetic field could be a key reason Earth is still habitable and Mars was unable to sustain life, as far as we currently know.

"The oldest previously known magnetic field from a terrestrial planet was on Mars, which was older than 4 billion years old," Tarduno said. "But then, sometime after 4 billion years ago, it died off. If you compare the evolution of Earth and Mars, Mars had a more dense atmosphere, and water, but it probably lost both to erosion from the solar wind because it didn't have a magnetic field to protect them, whereas Earth always appeared to have had a strong magnetic shield."

The scientists detailed their findings in the July 31 issue of the journal Science.

Follow us @livescience, Facebook & Google+. Original article on Live Science.

Huge wildfires sparked by a powerful El Niño event 16 years ago left a distinct tinge of sulfur in Antarctica's snow, a new study reports.

This is the first time researchers have detected a climate signal from El Niño-driven wildfires in Antarctica's snow. The discovery raises hopes that the signal, which is linked to a unique sulfur molecule, could be detected in older ice as well — and perhaps shed light on the chemistry of Earth's ancient rocks.

"We hope we would be able to go back and understand past El Niño events before anthropogenic [human] influences," said lead study author Robina Shaheen, a geochemist at the University of California, San Diego (UCSD). "The same chemistry was happening in the Precambrian [period] as well." [50 Amazing Facts About Antarctica]

Isotopes are versions of the same elements, such as sulfur, with different numbers of neutrons in their nuclei, giving them different mass. Four nonradioactive, or stable, isotopes of sulfur occur naturally on Earth. Researchers use sulfur isotopes to peer into the planet's conditions in the deep past, such as during the Precambrian period, before complex life arose on Earth.

When snow falls in Antarctica, it carries trace amounts of isotopes that are circulating in Earth's atmosphere. Because the snow doesn't melt completely each year, the layers are like time capsules of Earth's atmosphere. Eventually, this snow becomes ice, trapping and preserving more than a million years of atmospheric chemistry, researchers think.

Shaheen and her co-authors analyzed sulfur isotopes in snow that fell between 1984 and 2001 in Antarctica, looking at variations between the seasons. Their findings were published today (Aug. 4) in the journal Proceedings of the National Academy of Sciences.

The team saw spikes in sulfur levels caused by volcanic eruptions, which inject sulfate particles high into the atmosphere. The sulfate circles the Earth, and eventually some snows down on Antarctica.

But a strange pattern of sulfur anomalies also turned up in snow from 1997 to 1998, a season with no volcanic eruptions big enough to blast sulfur all the way to Antarctica.

"1998 is the biggest isotopic signal of them all," said study co-author Mark Thiemens, an isotope geochemist at UCSD. "It was a real surprise and totally unexpected."

The ratio of sulfur isotopes also changed dramatically in 1998, providing clues to the source of the unusual shift.

The researchers think the sulfur ratio changed because of raging wildfires caused by El Niño-triggered drought. The wildfires likely sent sulfur sky-high on huge pyrocumulonimbus clouds, the researchers said.

"The wildfires were so large that they shot a lot of sulfur into the stratosphere," Thiemens told Live Science. The stratosphere is the layer of Earth's atmosphere above the troposphere, which is the atmosphere humans live in and breathe.

According to their model, the source of the big sulfur shift could be a molecule called carbonyl sulfide. Burning plants emit both sulfate and carbonyl sulfide. In the stratosphere, ultraviolet (UV) light breaks down carbonyl sulfide into sulfur dioxide.

The unusual sulfur isotope pattern linked with carbonyl sulfide also turned out to be strikingly similar to rocks deposited before plants ever existed — in Earth's deep past, 2.4 billion years ago. This era marks a sudden jump in oxygen levels, which geochemists can detect in ancient rocks.

"The same photochemistry [caused by UV light] may have been happening in the Precambrian period," Thiemens said. The reaction could account for some of the sulfur deposited in rocks around the time that oxygen levels started to rise. Accurately counting those sulfur levels is important because they affect estimates of how much oxygen was present in Earth's atmosphere 2.4 billion years ago.

Shaheen added, "Carbonyl sulfide [has been] totally ignored in models of when oxygen started to increase on the planet."

Email Becky Oskin or follow her @beckyoskin. Follow us @livescience, Facebook & Google+. Original article on Live Science.

The U.S. Air Force has notified Congress that it intends to shut down HAARP, a controversial Alaska-based research facility that studies an energetic and active region of the upper atmosphere.

Conspiracy theorists are abuzz about the news, given that HAARP (short for High Frequency Active Auroral Research Program) has long been the center of wild speculation that the program is designed to control the weather — or worse. In 2010, Venezuelan leader Huge Chavez claimed that HAARP or a program like it triggered the Haiti earthquake.

For the record, the Haitian quake of 2010 was caused by the slippage of a previously unmapped fault along the border of the Caribbean and North American tectonic plates.

HAARP is a research program designed to analyze the ionosphere, a portion of the upper atmosphere that stretches from about 53 miles (85 kilometers) above the surface of the Earth to 370 miles (600 km) up. The program has been funded by the Air Force, the Navy, the University of Alaska and DARPA (the Defense Advanced Research Projects Agency). [20 of the best conspiracy theories]

Why HAARP exists

The U.S. military is interested in the ionosphere because this portion of the atmosphere plays a role in transmitting radio signals. HAARP sends radio beams into the ionosphere to study the responses from it — one of the few ways to accurately measure this inaccessible part of the atmosphere.

HAARP operates out of the HAARP Research Station in Gakona, Alaska, where it has a high-power radio frequency transmitter that can perturb a small portion of the ionosphere. Other instruments are then used to measure the perturbations.

The goal of the program is to understand the physics of the ionosphere, which is constantly responding to influences from the sun. Solar flares can send solar particles racing toward Earth, occasionally disrupting communications and the electrical grid. If scientists could better understand what happens in the ionosphere, they might be able to mitigate some of these problems.

But the Air Force is no longer interested in maintaining HAARP, according to David Walker, the Air Force deputy assistant secretary for science, technology and engineering.

At a Senate hearing on May 14, Walker said the Air Force has no interest in maintaining the site, and is moving in another direction in ionospheric research.

Politics and conspiracy

The Air Force's plan to destroy HAARP has detractors.

"While the Air Force neither wants nor appreciates the unique value of HAARP, users from several federal agencies, laboratories and universities, and friendly nations such as Canada, Britain, Taiwan, South Korea, Sweden and Norway, are eager to use its unique resources, which would further spread American influence and leadership," Dennis Papadopoulos, a professor of physics and astronomy at the University of Maryland, wrote in an outraged opinion piece in the Alaska Dispatch.

HAARP cost more than $290 million to build, much of it earmarked by late Senator Ted Stevens (R-Alaska), who had great influence over the U.S. defense budget during his time in Congress. The site was host to numerous projects over the years, including the creation of the first man-made aurora in 2005. The site's generators now require remediation to meet the environmental standards set in the Clean Air Act, an expense no one seems keen to take on.

But conspiracy theorists think HAARP's purpose is far more sinister than meets the eye. The program has been blamed for everything from global warming to natural disasters to mysterious humming noises in the sky.

Name a natural phenomenon, and someone probably suspects HAARP of being behind it. Online, conspiracy theorists suggest that HAARP was to blame for the 2011 earthquake and tsunami in Japan; the Moore, Oklahoma, tornado of 2013; a landslide in 2006 in the Philippines; and many more natural disasters. Other conspiracy theories hold that HAARP controls people's minds or is capable of altering the very fabric of reality.

These theories have yet to subside, even though very little has been going on at HAARP over the past year. In May 2013, the site shut down during a change in operations contractors. At the time, the HAARP program manager told reporters that the site was temporarily closed and locked, with only one DARPA project left to wrap up by early 2014.   

Follow Stephanie Pappas on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on Live Science.

Red electrical flashes that mysteriously hover above some thunderstorms have long puzzled scientists, but now, new research reveals how these alienlike atmospheric sprites form.

Sprites form at irregularities in the plasma, or charged particles of gas, in the ionosphere, the layer just above the dense lower atmosphere, about 37 to 56 miles (60 to 90 kilometers) above the Earth's surface, a study found. Since disturbances in the ionosphere can affect radio communication, sprites could be useful for sensing such disturbances remotely, researchers say.

"We would like to know how sprites are initiated and how they develop," Victor Pasko, an electrical engineer at Penn State and author of the study published May 7 in the journal Nature Communications, said in a statement. [Images: Red Sprite Lightning Revealed in Stunning Photos]

Sprites are large electrical discharges that occur above thunderstorms. They resemble reddish-orange jellyfish with bluish tentacles streaming down.

But while sprites require thunderstorms, not all thunderstorms produce sprites. Recent studies suggested that ionosphere irregularities were required for these ghostly flashes to occur, but evidence for them was lacking.

In the study, Pasko and his colleagues studied high-speed video of sprites, and developed a model for how the strange lightning evolves and disappears. They used the model to try to recreate sprite-forming conditions.

Analysis of the videos showed that streamers snake downward from the sprites much more quickly than they spread horizontally, suggesting plasma irregularities were driving the streamer spread.

To study sprite dynamics, the team used a two-dimensional mathematical model of the movement of charged particles in the sprite. They used the model to recreate how sprites are formed, using it to see how the streamers originated and how large the plasma irregularities were.

Several sources could be causing these irregularities in the plasma. The existence of a previous sprite is the most obvious, but there were none that occurred in the region studied that occurred close enough in time — unless the irregularities last much longer than scientists suspect.

Alternatively, meteors could cause irregularities as they move through the upper regions of the ionosphere, before burning up in the lower atmosphere due to friction.

The high-speed videos and models could be useful to do remote sensing of the ionosphere, to understand how natural phenomena impact long-range radio communication, the researchers said.

Follow Tanya Lewis on Twitter and Google+. Follow us @OAPlanet,Facebook and Google+. Original article at Live Science's Our Amazing Planet.

Updated Tues., April 22 at 1:34 p.m. ET.

Mysteriously, most of the gas xenon that scientists expected to find in Earth's atmosphere is missing. Now, researchers say they might have the answer to this puzzle: This noble gas, which usually does not bond with other atoms, may chemically react with iron and nickel in Earth's core, where it's held.

Xenon is a noble gas, so, like other noble gases, such as helium and neon, it is mostly chemically inert. Scientists have long analyzed xenon to study the evolution of Earth and its atmosphere.

Strangely, atmospheric levels of xenon are more than 90 percent less than scientists would have predicted based on levels of other noble gases such as argon and krypton. [8 Chemical Elements You've Never Heard Of]

"The missing xenon paradox is a long-standing question," said study author Yanming Ma, a computational physicist and chemist at Jilin University in Changchun, China.

Although some researchers have suggested this xenon may have escaped from the atmosphere into space, the majority of scientists think it is hidden in the Earth's interior. However, investigators have long failed to find a way in which Earth might incorporate this gas into chemically stable compounds — For instance, there is no known way for ice or sediments to realistically capture xenon on Earth, meaning it should just escape into the atmosphere.

Past research had suggested Earth's core might hold xenon. However, "all the previous attempts to implicate the capture of xenon in the Earth's core have failed," Ma said.

Earth's core, which contains about one-third of the planet's mass, is made of iron and nickel. In 1997, scientists reported experiments that suggested xenon would not react with iron.

"Through a careful analysis of their work, however, we found that the experiment was carried out only up to 150 gigapascals, a pressure far from the Earth's inner-core pressure of 360 gigapascals," Ma said. (In comparison, 1 gigapascal is more than nine times greater than the pressure at the bottom of the Mariana Trench, the deepest part of the ocean.)

This past research also theoretically extrapolated what might happen if xenon were trapped at the high pressures found in Earth's inner core, and concluded that xenon would not bond with iron. However, those prior studies assumed xenon would form a so-called "hexagonal close-packed lattice" — essentially, a lattice of atoms resembling a solid whose bottom and top faces are hexagons and whose side faces are rectangles. This assumption was made because iron atoms normally form this kind of structure with other iron atoms.

However, Ma and his colleagues reasoned that, if the structures of iron-xenon compounds are different, they could form a compound. Their calculations now suggest that at the extreme temperatures and pressures found in Earth's core, xenon can bond with both iron and nickel. The most stable of these molecules are ones with one xenon atom and three iron atoms — XeFe3 — or one xenon atom and three nickel atoms — XeNi3. XeFe3 forms cubic lattices, while XeNi3 forms lattices whose top and bottom faces are hexagons and whose side faces are triangles.

These findings suggest Earth's core may hold all of the missing xenon. "We do hope future high-pressure experiments can be carried out to confirm our predictions," Ma said. Such high pressures could be achieved by squeezing objects between diamonds.

However, for those high-pressure experiments, "a high temperature of more than 6,000 Kelvin (10,340 degrees Fahrenheit or 5,727 degrees Celsius) must be applied. Such a high temperature, if not properly controlled, can easily lead to the breaking of the diamonds used for pressure generation. This might be the major obstacle for the experiment."

It remains uncertain what effects, if any, these xenon compounds might have had on the evolution of Earth's core. "This needs to be more deeply analyzed," Ma said.

The scientists detailed their findings online April 20 in the journal Nature Chemistry.

Editor's Note: This article was updated to fix some odd wording that occurred during the editing process.

Follow us @livescience, Facebook& Google+. Original article on Live Science.

The moon came into existence after several planet-size space bodies smashed into the nascent Earth one after the other, with the final one actually forming our satellite, while several impacts repeatedly blew off our planet’s atmosphere, according to a new study.

Until now, scientists thought it was unlikely that the early Earth could lose its atmosphere because of a giant moon-forming impact. But the new research, based on recent studies showing that at its infancy our planet had magma oceans and was spinning so rapidly that a day was only two or three hours long, argues that this may have been possible.

"Part of the Earth remembers its infancy, and it's giving us clues to the stages of growth of the Earth," said planetary scientist Sarah Stewart, a professor at Harvard University.  [The Moon: 10 Surprising Lunar Facts]

Stewart presented her idea, developed along with Harvard colleagues Sujoy Mukhopadhyay, Simon Lock and Jonathan Tucker, at a Royal Society conference in London on the origin of the moon. The study will be published in the journal Philosophical Transactions of the Royal Society.

The teambased the research on two recent studies, one of which Stewart conducted with Matija Cuk of the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, Calif., in 2012.

That research argued that the moon is actually a giant merger of bits and pieces of our own planet, partially destroyed by a catastrophic collision with a space body 4.5 billion years ago.

Back then, the Earth had a two- or three-hour day, she said, and the impact made it throw off enough material to coalesce into what became our satellite, making it the Earth’s geochemical twin. [How the Moon Evolved: A Video Tour]

This ultra-rapid spin is one of the important conditions necessary to make the atmospheric loss theory work, Stewart said.

The other criterion is the presence of terrestrial magma oceans — and this hypothesis has now got support thanks to new data obtained from volcanoes.

Volcanic memory

Tucker and Mukhopadhyay, who presented their work at the 44th Lunar and Planetary Science Conference in March, sampled elements from volcanoes in Iceland, which have rocks that are among the oldest on Earth and thus retain the geochemical signatures of the Earth's so-called lower-most mantle, closestto the planet’s core.

They also looked at elements found in volcanoes that sample the upper mantle, such as mid-ocean ridge basalts at the bottom of the Atlantic.

They found that elements in the deep mantle that retain a very ancient chemistry, from the times of the Earth's formation, are very different from those in the upper mantle we see today.

In particular, the presence of two noble gases, helium and neon, is very different today from what it used to be, Stewart said. Both these gases are very rare on today's Earth, but they are found in the solar system in abundance.

And as "documented" by the deep Earth, when our planet was just forming it contained much more helium and neon as well. 

"The implication is that [the lower-most mantle] hasn’t been completely overprinted by subsequent evolution, and it’s helping us pinpoint events that had to happen to lead to the planet we see today,"  Stewart said.

So how and why did these gases disappear?

While helium is not gravitationally bound to the Earth, neon is, and it needs a powerful "kick" to escape.

"For such a dramatic change to happen, you can’t do that with just open loss off the top — instead, you need to eject the whole atmosphere in a catastrophic type of event, a giant impact," Stewart said.

Besides atmospheric loss caused by impacts that melt all rock to create magma oceans, to get to the present-day neon-to-helium ratio Earth would have to suffer multiple impacts. In other words, the Earth probably lost its primordial atmosphere multiple times, and the magma oceans were melting more than once.

The final impact, Stewart says, led to the creation of the moon, and resulted in the ratio of the gases we have today. "One single impact is not sufficient, there had to be at least two, probably more, to make that work," Stewart said.

No mixing?

The idea that stages of Earth's growth are recorded in chemistry is relatively new.

Previously, researchers argued that during our planet’s formation (known as accretion) with a moon-forming impact, the proto-Earth was melted and mixed to the point that it "forgot" its growth — all the data was erased.

"But now what we've learned is that data wasn’t erased, and it's exciting because now we have clues to the stages of growth," Stewart said.

She added that the next step would be to calculate exactly under what impact conditions the early atmosphere actually might have been blown off.

But if the early atmosphere disappeared due to an impact, how did the Earth get its atmosphere back and how did it finally evolve into the one we have today?

Stewart says that after the last giant smashup that finally formed the moon, the Earth continued to form, accreting planetesimals — mountain-size space rocks that stuck to it, making it bigger. 

"Theseplanetesimals delivered some of Earth’s volatiles," she says, eventually bringing the atmosphere to the state it is in today. Volatiles are elements able to escape very easily.

Ian Crawford of Birkberk College, University of London, who was not involved in the study, said that the theory sounded plausible "because multiple impacts are expected to happen in the context we think the solar system was put together."

"It's true that each time you have a giant impact you expect a magma ocean to form. And the early planets are expected to have a transient atmosphere, so it is possible that the atmosphere would be released if the magma ocean solidified."

Another researcher who did not take part in the research, Robin Canup of the Southwest Research Institute in Boulder, Colo., said Stewart's theory sounded "very interesting."

But, she said, "The issue is whether we require a specific sequence of multiple impacts to form the moon. Once you do that, [you assume] that each of them probably have a somewhat small probability. When you multiply these probabilities together, you end up with a very small probability.

"Then you have to ask, is this really the right solution?"

Follow Katia Moskvitch on Twitter @SciTech_Cat. Follow SPACE.com on Twitter @Spacedotcom. We're also on Facebook and Google+. Original article on SPACE.com.

A new study that claims to present evidence of alien life is being met with a healthy dose of skepticism in the scientific community.

On July 31, a team of British researchers sent a balloon into the stratosphere over England, where it collected samples at an altitude range of 14 miles to 17 miles (22 to 27 kilometers). The balloon's scientific payload returned to Earth toting the cell wall, or frustule, of a type of microscopic algae called a diatom, the scientists report in the Journal of Cosmology.

While bacteria and other tiny lifeforms have been found high above the planet before — storm clouds are teeming with microbes, for example — the new discovery is potentially of monumental importance, study team members say. [5 Bold Claims of Alien Life ]

"Most people will assume that these biological particles must have just drifted up to the stratosphere from Earth, but it is generally accepted that a particle of the size found cannot be lifted from Earth to heights of, for example, 27 km. The only known exception is by a violent volcanic eruption, none of which occurred within three years of the sampling trip," lead author Milton Wainwright, of the University of Sheffield in the United Kingdom, said in a statement Thursday (Sept. 19).

"In the absence of a mechanism by which large particles like these can be transported to the stratosphere, we can only conclude that the biological entities originated from space," Wainwright added. "Our conclusion then is that life is continually arriving to Earth from space, life is not restricted to this planet and it almost certainly did not originate here."

The diatom fragment may have been delivered to Earth by a comet, Wainwright and his colleagues write in the paper, which can be read here at the Journal of Cosmology.

Extraordinary claims require extraordinary evidence

The idea that life is widespread throughout the universe and has been spread to many worlds by objects such as comets — a notion known as panspermia — is credible, at least over relatively short cosmic distances, said astronomer Seth Shostak of the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, Calif.

However, that doesn't necessarily mean the new study will stand up to the intense scientific scrutiny it's likely to receive, he said.

"In the past, most members of the astrobiology community have found it easier to ascribe these claims to terrestrial contamination than to extraterrestrial hitchhikers," Shostak told SPACE.com via email. "It remains to be seen whether that opinion will be changed by these new results." [10 Alien Encounters Debunked]

Indeed, other scientists said they would like to see more convincing evidence of a cosmic origin for the organism snagged by the balloon.

"There is probably truth to the report that they find curious stuff in the atmosphere," Chris McKay, an astrobiologist at NASA's Ames Research Center in Moffett Field, Calif., told SPACE.com via email. "The jump to the conclusion that it is alien life is a big jump and would require quite extraordinary proof. (The usual Sagan saying: extraordinary claims require extraordinary evidence.)"

McKay gave an example of what might constitute such extraordinary evidence.

"If they were able to show that it was composed of all D amino acids (proteins in Earth life are made of L amino acids), that would be pretty convincing to me," he said. "So some sort of biochemical indication that it does not share Earth biochemistry. If it does indeed share Earth biochemistry, proving that it is of alien origin is probably impossible."

Further study needed

Wainwright and his team plan to study their stratospheric samples further in an attempt to find a smoking gun for an off-Earth origin. For example, the researchers will analyze the ratios of various isotopes, which are varieties of an element that have different numbers of neutrons in their atomic nuclei. 

"If the ratio of certain isotopes gives one number, then our organisms are from Earth; if it gives another, then they are from space," Wainwright said.

However, astrobiologist Dirk Schulze-Makuch of Washington State University thinks the study team should have performed such follow-up analyses, and consulted diatom experts, before publishing its provocative claim.

"Perhaps the fragment came actually from the stratosphere and is not contamination, but basing this conclusion only on one particle and very limited analysis seems quite odd to me and inferring an extraterrestrial origin completely off-base," Schulze-Makuch told SPACE.com via email.

Schulze-Makuch also thinks comets are unlikely incubators for life, suspecting that life first arose on a planetary body. And the presence of a diatom on a comet would be especially surprising, he said.

"Diatoms are actually relatively advanced life forms on Earth and developed most likely sometime at the beginning of the Mesozoic (probably Jurassic time period), thus very late during evolution (probably at least 3 billion years after the origin of life on Earth)," Schulze-Makuch said, adding that diatoms are typically aquatic and there is no liquid water on a comet, except during the brief periods when the icy objects approach the sun.

"Besides, I would expect an extraterrestrial organism or even remnant of an organism to be quite different from what we see on Earth in some significant ways (as the environment around it, its 'habitat,' will affect the form and function of the organism), and certainly not be linked to some kind of diatom species on Earth," Schulze-Makuch said.

Other controversial claims

The Journal of Cosmology is no stranger to bold claims. Two years ago, for instance, it published a controversial study that purported to have found evidence of fossilized life in meteorites.

That paper was not well received by outside scientists, some of whom questioned the journal's credibility as well.

"It isn't a real science journal at all, but is the ginned-up website of a small group of crank academics obsessed with the idea of [Fred] Hoyle and [Chandra] Wickramasinghe that life originated in outer space and simply rained down on Earth," P.Z. Myers, a biologist at the University of Minnesota, Morris, wrote on his popular science blog Pharyngula at the time.

Wickramasinghe is a co-author of the new stratospheric diatom paper, a fact that could color its reception in the wider scientific community.

"I don't have ANY expertise in this area," Rosie Redfield, a microbiologist at the University of British Columbia, told SPACE.com via email. Redfield was among the outspoken critics of the Journal of Cosmology's 2011 meteorite announcement. "But neither the Journal of Cosmology nor Dr. Wickramasinghe have any scientific credibility, and one fragment of a diatom frustule is hardly significant evidence."

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on SPACE.com.

NASA launched two small rockets from Virgina's Eastern Shore today in an early Fourth of July fireworks display aimed to probe the electrical eddies of the Earth's upper atmosphere.

The two small rockets blasted off within 15 seconds of each other from NASA's Wallops Flight Facility on Wallops Island, Va. The mission: to probe the global electrical current in the winds of Earth's ionosphere with instruments mounted to a Black Brant V booster and a Terrier-Improved Orion sounding rocket.

"We have liftoff of the Black Brant V & Terrier-Improved Orion, for an Independence Day fireworks show," NASA Wallops officials wrote in a Twitter post marking launch success.

The Black Brant V rocket launched at 10:31:25 a.m. EDT (1431:25 GMT), with the Terrior-Improved Orion rocket following at 10:31:40 a.m. EDT (1431:40 GMT).

NASA's Fourth of July rocket launches were part of the Daytime Dynamo mission, a joint project with the Japan Aerospace Exploration Agency to study how electrical currents move in Earth's ionosphere between 30 and 600 miles (48 and 965 kilometers) above the surface. People on Earth rely on this current in the ionosphere, called the dynamo, every day.

Radio signals are bounced off the ionosphere during broadcasts and satellite communication and navigation signals must travel through the ionosphere in order to reach the Earth. Then the ionosphere is disturbed, these signals can be distorted, NASA officials said.

The larger Black Brant V rocket carried instruments to measure the neutral and charged particles in Earth's ionosphere, while the smaller Terrier-Improved Orion released a lithium gas compound designed to allow scientists on the ground track the electrical current wind patterns. The two rockets were expected to reach an altitude of about 100 miles (160 kilometers), but not fly high and fast enough to orbit the Earth.

The rocket launch came after days of delays due to unfavorable weather at the Wallops launch range. Cloudy weather and high winds prevented several launch attempts, which began June 24. It was only by coincidence that the rocket launch coincided with the annual U.S. Independence Day holiday.

"Happy Fourth of July everyone," a launch controller told the mission team shortly after liftoff. "We beat everyone by putting some rockets into the air."

This story was provided by SPACE.com, a sister site to Live Science.  Email Tariq Malik at tmalik@space.com or follow him @tariqjmalik and Google+. Follow us @Spacedotcom, Facebook and Google+. Original article on SPACE.com.

Glowing red arcs invisible to the naked eye have now been detected high above most of Europe using advanced cameras pointed at the sky.

When streams of high-energy, charged particles come rushing from the sun to batter Earth, they cause what are called geomagnetic storms. These events are disruptions in the magnetosphere, the part of Earth's atmosphere dominated by the planet's magnetic field. The most dramatic effects of these storms are giant, bright auroras in Earth's polar regions, but the tempests result in other striking consequences as well, such as faintly glowing red arcs high up in the ionosphere. This is the electrically charged part of Earth's atmosphere, stretching from about 50 to 370 miles (85 to 600 kilometers) above the Earth.

The arcs give off a very specific wavelength of red light, but are too faint to see with the naked eye. They appear at lower latitudes, unlike auroras, which typically occur over higher latitudes.

Scientists had thought there was too much light pollution over Europe for the dim, red arcs to be visible. But now, the new All-Sky Imaging Air-Glow Observatory (ASIAGO), located in northern Italy, is using cameras with highly sensitive sensors and a fish-eye lens to observe these red arcs and faint auroral activity over most of the continent. [Image Gallery: Amazing Auroras]

An international team of scientists watched the sky with the observatory during a geomagnetic storm that struck Earth in 2011. After comparing their observations with satellite- and ground-based observations, the researchers found that red arcs could reach all the way down to Europe, stretching from Ireland in the west to Belarus in the east.

The fact that scientists can now see these arcs over Europe means that, in combination with similar data from the Americas and the Pacific Ocean, researchers can now see how long the arcs stretch across vast distances over the planet "and thus how long it takes the magnetosphere to be drained of its storm-time energy," researcher Michael Mendillo, a space physicist at Boston University, told OurAmazingPlanet. (Red arcs happen when oxygen atoms in the ionosphere emit light, after being excited by electrons heated at greater heights in Earth's magnetosphere.)

Such data could in turn help scientists analyze the effects of space activity on radio communications in real time and support projects aiming to model space weather, researchers added.

The scientists detailed their findings online Feb. 25 in the journal Space Weather.

Follow OurAmazingPlanet @OAPlanet, Facebook & Google+. Original article at LiveScience's OurAmazingPlanet.

GOLDEN, Colo. — Talk about ballooning expectations. How about launching your own payloads into the exotic environment of near space?

High-altitude balloon flights are becoming cheaper and more widely available, expanding research opportunities for scientists and hobbyists, as well as young people just learning how science works.

In the last year or so, for example, schoolkids have lofted a number of balloons to the stratosphere, including three carrying a Lego figure, a Hello Kitty doll and bobblehead versions of Barack Obama and Mitt Romney, respectively.

"You can launch hardware to the very edge of space on a budget," said Joseph Maydell, founder and chief engineer of High Altitude Science, which provides balloon-mission hardware and services. "We've adopted a keep-it-simple philosophy." [Barack O'Bobblehead Flies to the Stratosphere (Video)]

Bringing near-space science to the masses

Maydell is a former flight controller for the International Space Station at NASA's Johnson Space Center in Houston. Viewing downlinked images of Earth taken from aboard the orbiting lab helped inspire him to found Colorado-based High Altitude Science in 2011, he said.

“I was awestruck by the beauty of our planet and the ability to be in space," Maydell told SPACE.com. "I really wanted to share that with as many people as possible."

Weather balloons seemed like the most accessible and affordable way to make that happen, he added. High Altitude Science provides balloon launch services to customers with specific near-space needs — such as scientific research, space hardware prototype testing and advertising — and others interested in the sheer fun of it.

"We've got a wide plethora of customers," Maydell said, from folks interested in curve-of-the-Earth imagery to those who want to assess the speed of the jet stream or measure high-altitude temperatures and pressures. "Some are launching gliders from the edge of space or doing some other bigger research projects."

Weather balloons can rise to an altitude of 24 miles (39 kilometers) or more before they burst, and a payload may land (via parachute) up to 75 miles (120 km) away, depending on wind conditions at the launch site, Maydell said.

Though outer space doesn't technically begin until you get 62 miles (100 km) above Earth's surface, the views are still great from 24 miles up. At that altitude, the sky is black and the curvature of the Earth is clearly visible, Maydell said.

"It’s about the closest an average person can get to being in space, and you can do it for about the price of a nice iPad,” Maydell said.

Hello Kitty gets a ride

One recent user of High Altitude Science services was Lauren Rojas, a seventh-grader at Cornerstone Christian School in Antioch, Calif.

Rojas' Hello Kitty doll soared to an altitude of 93,625 feet (28,537 meters), gaining a spectacular view of Earth before coming back down in a tree-snagging parachute landing.

Hello Kitty's mission also involved onboard sensors to gauge temperature, air pressure and altitude, along with cameras that documented the ride.The video of Hello Kitty's trip has been an Internet sensation, garnering more than 820,000 views since it was posted on YouTube on Jan. 25.

This story was provided by SPACE.com, sister site to Live Science.  Leonard David has been reporting on the space industry for more than five decades. He is former director of research for the National Commission on Space and a past editor-in-chief of the National Space Society's Ad Astra and Space World magazines. He has written for SPACE.com since 1999. Follow SPACE.com on Twitter @Spacedotcom, and on Facebook & Google+. Original article on SPACE.com.

A rare glimpse of a "gigantic jet" — a huge and mysterious burst of lightning that connects a thunderstorm with the upper atmosphere — was made over China in 2010 and was recently described by scientists.

The gigantic jet took place in eastern China on Aug. 12, 2010 — the farthest a ground-based one has ever been observed from the equator, according to the research team.

Previous jets were mainly seen in tropical or subtropical regions, but this one took place around 35 degrees latitude, about the same as the southern part of Tennessee in the United States.

"This is the first report from mainland China," lead researcher Jing Yang, an atmospheric scientist with the Chinese Academy of Sciences in Beijing, told OurAmazingPlanet. The results were recently published in the Chinese Science Bulletin.

Researchers got a good look at the storm using a variety of tools, including Doppler radar data and weather pictures in the infrared band of radiation.

The gigantic jet peaked at about 55 miles (89 kilometers) above the ground, far above the cloudtops that were measured with Doppler radar at an altitude of 11 miles (17 km). [Infographic: Earth's Atmosphere Top to Bottom]

Yang added that her team had possibly seen another gigantic jet in the same area during a different thunderstorm, but said they needed to recheck the data to confirm.

"It's not as clear as this one if it is a gigantic jet or not," she said.

It wasn't until the last century that electrical activity above thunderclouds was scientifically proven, although rumors based on undocumented observations circulated long before that time.

These electrical discharges can take several forms, such as sprites (orange-red flashes) and blue jets, which appear as blue cones.

The first confirmed gigantic jet was reported in 2001, after American researchers saw a blue jet reaching 44 miles (70 km) above the clouds at the Arecibo Observatory in Puerto Rico. This was nearly double the 26-mile (42 km) limit for jets that was previously observed.

Two years later, researchers described shapes such as "tree jets" and "carrot jets" that they spotted during a 2002 thunderstorm over the South China Sea near the Philippines.

While scientists are still trying to understand how these gigantic jets work, they believe the jets balance out the electrical charge during thunderstorms by discharging the ionosphere — a part of the upper atmosphere filled with charged particles.

Follow Elizabeth Howell @howellspace, or OurAmazingPlanet on Twitter @OAPlanet. We're also on Facebook and Google+.

Some of the coldest air on the planet lies above the tropics. And through this cold zone, more water than expected sneaks into the higher reaches of the atmosphere, a new study finds.

Upon reaching the stratosphere, the layer of the atmosphere above the one in which we live, water vapor acts as a potent greenhouse gas and destroys the protective ozone.

"Small changes in the humidity of the stratosphere are important for climate," said Eric Jensen, lead study author and a scientist at NASA's Ames Research Center in Moffett Field, Calif.

Where the water goes

Because it's difficult to measure, scientists have been unsure how much water passes from the troposphere, the layer of Earth's atmosphere we breathe, into the stratosphere (which runs from about 6 to 31 miles, or 10 to 50 kilometers, above Earth's surface), Jensen said. At the boundary between the two zones, called the tropopause, the air is minus 120 degrees Fahrenheit (minus 90 degrees Celsius).

Researchers suspected water vapor rising into the tropopause would freeze and fall out in wispy cirrus clouds made entirely of ice crystals. In essence, they thought that the tropopause was a cold trap for water, keeping the vapor out of the stratosphere. [Infographic: Earth's Atmosphere Top to Bottom]

"That turned out to be a bit of an over-simplification," Jensen told OurAmazingPlanet.

Flying high

In 2011, NASA sent a remote-controlled aircraft, a Global Hawk drone, on three flights through cirrus clouds high the tropical tropopause, which Jensen calls the "gateway into the stratosphere."

Large-scale convection currents in the atmosphere bring air upwards in the tropics, driving water into the stratosphere, Jensen said. Thunderstorms can also punch water (and pollutants) directly through the tropopause.

The flights were part of an ongoing science experiment called ATTREX, for Airborne Tropical TRopopause Experiment, meant to help scientists better understand the upper atmosphere and its chemistry. The aircraft can fly up to 65,000 feet (19 km) in altitude and cover a large chunk of the tropics during a 30-hour round-trip from its current base in Palmdale, Calif.

Monitoring equipment mounted on the plane revealed that tropical cirrus clouds don't remove as much water vapor as models predicted, Jensen said.

"We found this is sort of a leaky cold trap, because a lot more water is getting through," he said.

In general, clouds form when air is super-saturated — when there is more water than the air can hold (think of saturation as a relative humidity of 100 percent). But near the tropopause, there aren't enough ice crystals to quickly and effectively remove the vapor, the ATTREX flights discovered.

Water in the rising air has nothing to condense around, so some escapes into the stratosphere. The study found air crossing the tropopause with 1.6 to 1.7 times as much water as at saturation level.

The results were published online Jan. 22 in the journal Proceedings of the National Academy of Sciences.

Future ATTREX flights will also test how compounds that destroy ozone enter the atmosphere, Jensen said. Gaining a better idea of the amount of water vapor in the stratosphere could also help refine climate models.

"Ultimately, what we expect are improvements in the models that are used to predict climate change," Jensen said.

This story was provided by OurAmazingPlanet, a sister site to LiveScience. Reach Becky Oskin at boskin@techmedianetwork.com. Follow her on Twitter @beckyoskin. Follow OurAmazingPlanet on Twitter @OAPlanet. We're also on Facebook and Google+.

Strange, newly discovered structures in Venus' atmosphere are redrawing scientists' perceptions of the planet's magnetic environment.

The European Space Agency's Venus Express spacecraft spotted these enormous magnetic entities — called flux ropes — stretching for hundreds of miles in the planet's upper atmosphere, above the poles.

Flux ropes have been seen before around other planets, including Earth. They transport superheated plasma gas from one side of the "rope" to the other. But on Venus, scientists don't know why these phenomena form in the atmosphere, according to a paper published Dec. 26 in the journal Geophysical Research Letters. How long they exist, and how they dissipate, are also mysteries.

"It is a huge surprise," study leader Tielong Zhang, who holds dual affiliations at research institutions in China and Austria, wrote in an email to SPACE.com. [Photos of Venus by Venus Express]

Twisting magnetic lines

Magnetic flux ropes come together from twisted magnetic field lines. They have been spotted in magnetic fields all over the solar system.

On Earth, flux ropes form near the face of the planet opposite the sun. The stream of charged particles known as the solar wind flows around the planet and creates a "magnetotail" of charged particleson the other side.

Periodic solar outbursts known as coronal mass ejections arise from a type of flux rope. The delicate structures sit on top of the sun and transport matter and superheated gas from one part of the sun to another. Researchers believe that when the flux ropes become unstable, that's when the sun erupts.

Venus stands apart from most other planets in the solar system, however, because it has no magnetic field. Zhang said the ionosphere (or upper atmosphere) of Venus acts as an obstacle to the solar wind.

When Venus' atmosphere has a higher pressure than the incoming solar wind field, the ionosphere is considered "unmagnetized," meaning that it's free of all but the smallest magnetic field structures.

The ionosphere of Venus stays unmagnetized most of the time, until the solar wind reaches a higher pressure than the surrounding atmosphere and magnetizes it. In these conditions, relatively small flux ropes can form due to the higher speed of the solar wind rolling over the slower ionosphere, researchers said. [The 10 Weirdest Facts About Venus]

"The ionosphere is filled with these very small — kilometers across — flux ropes," Christopher Russell told SPACE.com. Russell is a space physicist at UCLA and a co-investigator on Zhang's study.

"That might seem large to somebody walking down the street, but in terms of the size of the ionosphere, they are small," said Russell, who was also the principal investigator of NASA's Venus Pioneer missionthat first spotted these structures.

Scientists have known about these small flux ropes for a generation, since Pioneer orbited Venus in the late 1970s and early 1980s.

But the giant flux ropes were completely unknown until Venus Express — which was in a different orbit than Pioneer — spotted them with its magnetometer in 2008 and 2009. And they likely are created by a very different process, Russell said.

Frequent flux ropes

Venus Express saw the giant flux ropes in magnetized regions of the Venusian ionosphere over the poles, where that region of the atmosphere of Venus made its closest approaches to the planet. According to the paper, these ropes happen "quite often" and are hundreds of miles long, about as long as the depth of the ionosphere.

Scientists determined that the flux ropes form from solar particles on the side of the planet facing away from the sun, in the magnetotail. As the ropes' magnetic fields twisted tighter, they passed from the equator region to the poles.

"It seems to be associated with a process known as reconnection, which is magnetic field lines joining up together and forming a new magnetic configuration," Russell said. On Earth, this is the driving force behind the planet's spectacular auroras, which also tend to originate in the magnetotail.

As Venus' flux ropes move over the poles, the local magnetic field they create is stronger than the background, Russell added. To better understand them, the scientists are now working on a statistical survey to figure out how often flux ropes occur in Venus' ionosphere, and where they are.

Zhang, who is the principal investigator for Venus Express' magnetometer instrument, noted that giant flux ropes were previously found in the atmosphere of Mars — but only in the southern hemisphere. Mars, like Venus, does not have a planet-wide magnetic field.

"The observation and formation of the large flux rope at Mars might raise speculative questions related to the giant flux ropes at Venus," Zhang said, but added it was too early to draw direct links.

At least one study, according to Zhang's paper, has drawn a link between the magnetic rocks found on Mars and the flux ropes found above the Red Planet.

But Mars is a much different environment than Venus, so the giant flux ropes found by Venus Express could arise for another reason, he said.

Zhang works for both the University of Science and Technology of China and the Austrian Academy of Sciences, while the rest of his paper's research team hails from Austria, the United States, Germany, China and the United Kingdom.

This story was provided by SPACE.com, a sister site to Live Science. Follow Elizabeth Howell @howellspace, or SPACE.com @Spacedotcom. We're also on Facebook and Google+.

Water may play a critical role in controlling the ozone gas high up in Earth's atmosphere that can act as a greenhouse gas or protect living things on the surface below from the sun's harmful ultraviolet rays, depending on where in the atmosphere it is found.

To better understand how water vapor and ozone interact, NASA plans to send a remote-controlled plane laden with monitoring equipment into the stratosphere — the layer of the atmosphere where protective ozone is found — above the tropics.

The drone will crisscross the tropopause, the boundary between the troposphere (they layer of the atmosphere we breathe and where most weather occurs), and the stratosphere. The boundary is a fluid layer whose thickness can change and depends on the latitude it is located over but that is generally found some 8 to 11 miles (5 to 7 kilometers) above Earth's surface.

In the middle reaches of the troposphere, ozone is a greenhouse gas, trapping heat and contributing to smog. But high in the troposphere and the stratosphere, the familiar ozone layer protects the planet from harmful UV radiation.

When storms punch water vapor through the tropopause, into the stratosphere, scientists suspect chemical reactions between water and free radicals such as chlorine may zap and destroy the protective ozone. The NASA experiment will sample this layer near the equator off the coast of Central America where tall thunderstorms often occur.

The flights, which start this month, are the first of a multiyear campaign to study how changes in water vapor in the stratosphere can affect global climate. The Airborne Tropical Tropopause Experiment (ATTREX) relies on a Global Hawk drone, which can cruise for 30 hours from its home at Edwards Air Force Base in California. The aircraft are also used by the U.S. Air Force and Navy.

Predictions of stratospheric humidity changes are uncertain because of gaps in the understanding of the physical processes occurring in the tropical tropopause layer, NASA said in a statement.

"The ATTREX payload will provide unprecedented measurements of the tropical tropopause," Eric Jensen, ATTREX principal investigator, said in a statement. "This is our first opportunity to sample the tropopause region during winter in the Northern Hemisphere when it is coldest and extremely dry air enters the stratosphere."

Reach Becky Oskin at boskin@techmedianetwork.com. Follow her on Twitter @beckyoskin. Follow OurAmazingPlanet on Twitter @OAPlanet. We're also on Facebook and Google+.

Actually, it's both, depending on what altitude you find it at …

Ninety percent of Earth's ozone is found in the stratosphere (the second layer of the Earth's atmosphere, just above the one in which we dwell, the troposphere). This ozone forms the ozone layer, which shields everything on the planet's surface from the sun's harmful ultraviolet rays.

But when ozone forms at the surface (when pollution from cars reacts with UV rays), it is a pollutant itself, and can damage forests, crops and can irritate human lungs.

Generally ozone stays at one level or the other, but occasionally, stratospheric ozone can be dragged down to the surface when the boundary that marks the shift from the warm air of the stratosphere to the cooler air of the troposphere (called the tropopause) rapidly jumps upward from its normal 8 to 10 kilometer (5 to 6.2 mile) height above the surface, a new study detailed in the Nov. 8 issue of the journal Nature finds. These events, known as ozone intrusions, are rare and don't last very long, which makes them hard to identify.

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Rising carbon dioxide levels at the edge of space are apparently reducing the pull that Earth's atmosphere has on satellites and space junk, researchers say.

The findings suggest that manmade increases in carbon dioxide might be having effects on the Earth that are larger than expected, scientists added.

In the layers of atmosphere closest to Earth, carbon dioxide is a greenhouse gas, trapping heat from the sun. Rising levels of carbon dioxide due to human activity are leading to global warming of Earth's surface.

However, in the highest reaches of the atmosphere, carbon dioxide can actually have a cooling effect. The main effects of carbon dioxide up there come from its collisions with oxygen atoms. These impacts excite carbon dioxide molecules, making them radiate heat. The density of carbon dioxide is too thin above altitudes of about 30 miles (50 kilometers) for the molecules to recapture this heat, which means it mostly escapes to space, chilling the outermost atmosphere. [Earth's Atmosphere from Top to Bottom (Infographic)]

Cooling the upper atmosphere causes it to contract, exerting less drag on satellites. Atmospheric drag can have catastrophic effects on items in space — for instance, greater-than-expected solar activity heated the outer atmosphere, increasing drag on Skylab, the first U.S. space station, causing it to crash back to Earth.

To see if the recent surge in carbon dioxide has made its way to the uppermost atmosphere, researchers analyzed changes in carbon dioxide concentrations at an altitude of about 60 miles (100 km) between 2004 and 2012 using the Atmospheric Chemistry Experiment Fourier Transform Spectrometer onboard the Canadian SCISAT-1 satellite. Since ultraviolet radiation from the sun can break carbon dioxide into carbon monoxide and oxygen, the investigators also looked at carbon monoxide levels to get a better picture of what average carbon dioxide levels were over time, since levels of solar radiation can vary from year to year.

The scientists discovered that concentrations of carbon dioxide and carbon monoxide, which they collectively dubbed COx, rose significantly over the past eight years. Their findings suggest a global increase in COx by about 23.5 parts per million per decade is going on right now.

Current levels of carbon dioxide are about 225 parts per million at an altitude of about 60 miles (100 km), compared to the 390 parts per million concentration seen in the troposphere, the level of the atmosphere closest to Earth's surface.

"We now have direct evidence that a major driver of upper atmospheric climate is changing," study lead author John Emmert, an upper atmospheric physicist at the Naval Research Laboratory in Washington, D.C., told SPACE.com.

This increase is 10 parts per million per decade faster than predicted by models of the upper atmosphere. Launching rockets into orbit does add carbon dioxide to the atmosphere, but the scientists calculated that such launches would have deposited only about 2,700 metric tons of carbon into the upper atmosphere between 2004 and 2012, while levels of COx apparently rose by about 20,000 metric tons in the upper atmosphere during that time.

Instead, the researchers suggest this increase was due to an unexpectedly large amount of mixing and circulation between the upper and lower layers of the atmosphere. The investigators also noted this rise in carbon dioxide levels in the upper atmosphere might explain the surprising reduction they have seen in atmospheric drag on satellites and space debris.

"The next challenge is to understand why the observed carbon dioxide trends are bigger than expected," Emmert said. "This requires the application of sophisticated, whole-atmosphere models."

The scientists detailed their findings online today (Nov. 11) in the journal Nature Geoscience.

This story was provided by SPACE.com, a sister site to LiveScience. Follow SPACE.com on Twitter @Spacedotcom. We're also on Facebook and Google+.

The U.S. presidential campaign was a political rollercoaster ride for Barack Obama and Mitt Romney, but it couldn't compare to the ride their bobblehead dolls took earlier this week.

On Monday (Nov. 5) — the day before President Obama defeated Romney to win a second term in the White House — a group of California schoolkids launched bobbleheads of the two candidates to the stratosphere aboard a high-altitude balloon.

"We estimate that the balloon reached 120,000 [feet]," Earth to Sky Calculus, a group of middle- and high-schoolers from Bishop, Calif., wrote on Facebook Wednesday. "It was a crystal clear, gorgeous fall day in the western United States!"

Onboard cameras documented the flight, recording the dolls' rise into the skies over east-central California and their dizzying descent after the balloon popped high above the Earth.

One video of the Obama and Romney dolls' flight, in fact, captures the transition from serenity to chaos after the balloon pops. The Obama doll's head is peacefully surveying the desert-mountain landscape one moment and bobbling furiously the next.

Earth to Sky Calculus eventually tracked down the fallen balloon and recovered its payload, group members said on Facebook.

Monday's launch wasn't the first balloon flight for some of the Bishop schoolkids. They also lofted a balloon in early September, as part of a project called The Golden iPod.

The Golden iPod is a nod to the Golden Records aboard NASA's Voyager spacecraft, which launched in 1977 and are now nearing the edge of interstellar space. The records are meant to provide any aliens who may come across them an introduction to our species and our planet; they contain selections of some of our most celebrated music, greetings in 55 different human languages and much more.

The Golden iPod project aims to fill a 16-gigabyte mp3 player with more indicators and accomplishments of human culture, then launch it to Earth orbit in 2013.

"We plan to fill our iPod with the best humanity has to offer — old and new," team member Anna Herbst said in a statement. "Then, if all goes as planned, we're going to send it to space."

Before it leaves the planet, the Golden iPod will visit the stratosphere during a series of high-altitude balloon flights, team members said. The first flight took place Sept. 5.

This story was provided by SPACE.com, a sister site to LiveScience. Follow SPACE.com senior writer Mike Wall on Twitter @michaeldwall or SPACE.com @Spacedotcom. We're also onFacebook and Google+.

Veteran skydiver Felix Baumgartner plans to take a supersonic tour of Earth's atmospheric layers on Tuesday (Oct 9). The Austrian daredevil will attempt the world's highest skydive, a daring leap from 23 miles up that will send him plummeting earthward faster than the speed of sound.

On the way down, Baumgartner, 43, will pass through the stratosphere and troposphere, two of the four gaseous layers that enshroud and protect our planet. Each of these layers has unique properties.

Earth's atmosphere starts 430 miles (690 kilometers) up. This is the upper boundary of the thermosphere, the outermost layer of the atmosphere. Solar radiation bombards this layer, striking its sparse air molecules and causing them to emit flashes of light: the auroras. At an altitude of 53 miles (85 km), the thermosphere transitions into the mesosphere, an atmospheric layer known for its faint clouds, as well as electrical discharge events called red sprites and blue jets.

Below the mesosphere is the stratosphere, and below that is the troposphere. These are the two layers through which Baumgartner will dive. [Infographic: Earth's Atmosphere Top to Bottom]

Baumgartner, sitting inside a custom-built capsule, will be lifted by a helium balloon to an altitude of 120,000 feet (36,576 meters). This altitude registers in the upper echelons of the stratosphere, the second layer of the atmosphere.

Near Earth's mid-latitudes, the stratosphere extends from an altitude of 6 miles (10 km) up to about 30 miles (50 km) above the surface. The air pressure drops from 10 percent of its value at sea level to just 0.1 percent of its sea-level value; no one can survive here without an oxygen tank.

The stratosphere is defined by the fact that in this layer, unlike in the layers above and below, absorption of ultraviolet sunlight by ozone causes the temperature to increase as you move up in altitude. This coupling of temperature with altitude prevents convection from happening, and so the air in this layer is dynamically stable.

Because the air is so thin in the stratosphere — the air pressure is just 0.1 percent of its sea-level value at the top of the layer and 10 percent of its sea-level value at the bottom — Baumgartner will freefall through it at speeds that surpass the sea-level speed of sound (760 mph, or 1,225 kph). As the air thickens, he'll gradually slow down before plunging into the troposphere, the innermost layer of Earth's atmosphere, where we live and breathe.

The troposphere, which includes everything from an altitude of 6 miles down over most of Earth (up to 12 miles down over the equator), is where all weather happens, as well as longer-term processes such as the jet stream. In this layer, temperature and pressure both drop as you move up in altitude.