Scientists using the James Webb Space Telescope just mapped the mysterious upper atmosphere of Uranus for the first time, revealing strange new features of the planet's mysterious magnetic field and glowing auroras.

The James Webb Space Telescope (JWST) observed Uranus rotating for 15 hours (nearly a full Uranian day) to learn more about how ice giants distribute energy in the upper layers of their atmospheres and to investigate how the planet's auroras operate.

Uranus' magnetic field is unique among the big planets of our solar system in that its magnetic pole is tilted by 60 degrees relative to its geographic pole. That tilt produces auroras that extend far beyond the poles of Uranus, unlike auroras on Earth.

To learn more, scientists used JWST to study Uranus' magnetosphere — the region of space around Uranus that's dominated by the planet's magnetic field.

"Uranus's magnetosphere is one of the strangest in the solar system," study lead author Paola Tiranti, a doctoral student at Northumbria University in the U.K., said in a European Space Agency (ESA) statement. "Webb has now shown us how deeply those effects reach into the atmosphere."

Strange lights on Uranus

JWST charted "the most detailed portrait yet" of how particles in Uranus' upper atmosphere are energized (ionized) by interactions with the sun, ESA officials said in the statement. The study, published Feb. 19 in the journal Geophysical Research Letters, aimed to measure ion temperature and density as far as 3,100 miles (5,000 kilometers) above the cloud tops of Uranus.

Temperature and density do not peak at the same altitude, JWST showed. Ions were the warmest between roughly 2,500 and 3,100 miles (4,000 and 5,000 km) but the densest at about 600 miles (1,000 km). This is because of the "complex geometry" of the planet's magnetic field, ESA officials said in the statement.

That geometry also produced two bright bands of auroras near Uranus' magnetic poles. In between the aurora belts, however, there is a "depletion" in both ion density and auroral emissions — an effect likely produced by transitions between the planet's magnetic-field lines, the scientists said. Observations at Jupiter's upper atmosphere have shown similar transition regions.

In addition to charting Uranus' upper atmosphere in three dimensions for the first time, JWST confirmed findings from previous studies that suggested the planet's upper atmosphere has been cooling steadily since the early 1990s. The telescope showed the average temperature of Uranus' atmosphere is about 307 degrees Fahrenheit (153 degrees Celsius), which is lower than the temperature measurements from other spacecraft and ground-based telescopes.

"By revealing Uranus's vertical structure in such detail, Webb is helping us understand the energy balance of the ice giants," Tiranti said. "This is a crucial step towards characterizing giant planets beyond our solar system."

James Webb Space Telescope quiz: How well do you know the world's most powerful telescope?

Scientists may have solved a long-standing mystery surrounding Uranus' extraordinarily strong radiation belt.

A new analysis of Voyager 2 data suggests that a temporary space weather event may have made the planet's electron radiation belt more intense than usual as Voyager 2 was passing by. The findings could help to explain why the radiation belt was so much stronger than scientists had predicted it would be.

Radiation belts are formed from interactions between the solar wind and a planet's magnetic field. The sun emits a continuous stream of protons and electrons from its outer atmosphere, called the corona. For planets that have a global magnetic field, including Earth and Uranus, some of those energetic, charged particles get trapped in the magnetosphere.

In January 1986, Voyager 2 flew by Uranus and measured the strength of its radiation belts. While the ion radiation belt was a little weaker than expected, the electron radiation belt was much more intense than scientists had predicted — close to the maximum intensity Uranus could sustain. Since then, scientists have tried to figure out how and why this was the case.

"Science has come a long way since the Voyager 2 flyby," Robert Allen, a space physicist at the Southwest Research Institute (SwRI) and coauthor of the new research, said in a statement. "We decided to take a comparative approach looking at the Voyager 2 data and compare it to Earth observations we've made in the decades since."

Earth versus Uranus

In the study, published in November 2025 in the journal Geophysical Research Letters, Allen and colleagues revisited data collected by Voyager 2 during its flyby of Uranus. They found several similarities between the Voyager data and the data collected from Earth orbit during a space weather event in 2019.

Uranus' unusually intense radiation belt may have been caused by a "co-rotating interaction region," the team found. A co-rotating interaction region occurs when high-speed solar winds overtake slower solar wind streams. The phenomenon could have accelerated electrons and added energy to the radiation belt, the researchers said.

"In 2019, Earth experienced one of these events, which caused an immense amount of radiation belt electron acceleration," said study co-author Sarah Vines, a space physicist at SwRI. "If a similar mechanism interacted with the Uranian system, it would explain why Voyager 2 saw all this unexpected additional energy."

If that's the case, it raises many more questions about the physics of Uranus' magnetosphere and its interactions with the solar wind, including the radiation belt's stability during the extreme seasons caused by the planet's tilted axis of rotation. A spacecraft orbiting Uranus and collecting data from different parts of the magnetosphere could help address those questions, the researchers wrote in the study.

"This is just one more reason to send a mission targeting Uranus," Allen said in the statement. "The findings have some important implications for similar systems, such as Neptune's."

The interiors of Uranus and Neptune may be rockier than scientists previously thought, a new computational model suggests — challenging the idea that the planets should be called "ice giants."

The new study, published Dec. 10 in the journal Astronomy & Astrophysics, may also help to explain the planets' puzzling magnetic fields.

Uranus and Neptune are relatively large planets at the edge of the solar system; Neptune is the most distant planet, orbiting at 2.8 billion miles (4.5 billion kilometers) from the sun, on average. The extremely cold temperatures at these distances cause gases such as hydrogen, helium and water to condense into compressed ice slurries that form the planets' cores. As such, these planets have become known as ice giants.

"The ice giant classification is oversimplified as Uranus and Neptune are still poorly understood," lead study author Luca Morf, a doctoral student at the University of Zurich, said in a statement.

Far out planets

Morf and his supervisor, Ravit Helled, developed a new hybrid model in an attempt to better understand the interior of these cold planets. Models based on physics alone rely heavily on assumptions made by the modeler, while observational models can be too simplistic, Morf explained. "We combined both approaches to get interior models that are both unbiased and physically consistent," he said.

The pair started by considering how the density of each planet's core could vary with distance from the center of the planets and then adjusted the model to account for the planets' gravities. From this, they inferred the temperature and composition of the core and generated a new density profile. The team inputted the new density parameters back into the model and iterated this process until the model core fully matched current observational data.

This method generated eight total possible cores for both Uranus and Neptune, three of which had high rock-to-water ratios. This shows that the interiors of Uranus and Neptune are not limited to ice, as previously thought, the researchers said.

All of the modeled cores had convective regions where pure water exists in its ionic phase. This is where extreme temperatures and pressures cause water molecules to break apart into charged protons (H⁺) and hydroxide ions (OH^-). The team thinks such layers may be the source of the planets' multiple magnetic fields, which cause Uranus and Neptune to have more than two poles. The model also suggests that Uranus' magnetic field is generated closer to its center than Neptune's is.

"One of the main issues is that physicists still barely understand how materials behave under the exotic conditions of [high] pressure and temperature found at the heart of a planet [and] this could impact our results," Morf said. The team aims to improve their model by including other molecules, like methane and ammonia, which also may be found in the cores.

"Both Uranus and Neptune could be rock giants or ice giants depending on the model assumptions," Helled said. She noted that much of our understanding of these planets may be incomplete, as it's based largely on data collected by the Voyager 2 space probe in the 1980s.

"Current data is insufficient to distinguish the two, and we therefore need dedicated missions to Uranus and Neptune that can reveal their true nature," Helled added

The team hopes the model may act as an unbiased tool for any new data from future space missions to these planets.

The James Webb Space Telescope has spotted a never-before-seen moon orbiting Uranus, bringing the planet's count of natural satellites to 29.

The moon, for now dubbed S/2025 U1, is just 6 miles (10 kilometers) in diameter, which is why it was invisible to other telescopes and the Voyager 2 spacecraft when it made its 1986 flyby of the icy planet.

Now, the James Webb Space Telescope's (JWST) Near-Infrared Camera (NIRCam) has detected glints of sunlight in a series of 10 40-minute long-exposure images of Uranus, which revealed the elusive moon's presence. The discovery hints that much more remains hidden around Uranus, the astronomers who found the moon say.

"No other planet has as many small inner moons as Uranus, and their complex inter-relationships with the rings hint at a chaotic history that blurs the boundary between a ring system and a system of moons," Matthew Tiscareno, a senior research scientist at the SETI Institute in Mountain View, California, and a member of the research team, said in a statement. "Moreover, the new moon is smaller and much fainter than the smallest of the previously known inner moons, making it likely that even more complexity remains to be discovered."

First spotted in 1781 by the German-British astronomer Frederick William Herschel, Uranus is the seventh planet from our sun and orbits it at a distance of 1.8 billion miles (2.9 billion km), nearly 20 times farther than Earth, according to NASA.

This extreme distance means that much of what we know about the far-flung, icy and lopsided planet comes from data gathered by NASA's Voyager 2 spacecraft, which zipped past the ice giant 40 years ago — yet even this information has been revised.

Related: Surprised scientists discover the 'dark sides' of Uranus' moons are the wrong way around

The newfound moon, the 14th member of a system of small moons inside the orbits of the largest moons Miranda, Ariel, Umbriel, Titania and Oberon, is 35,000 miles (56,000 km) from Uranus' center. It has a nearly circular orbit, meaning it may not have moved far from where it formed. Its location within Uranus' dark inner rings (the planet has 13, divided into an inner system and an outer pair) likely explains why it went undetected for so long.

An official name for the newly discovered moon is awaiting approval by the International Astronomical Union (IAU), but it will most likely be named for a character from the works of Shakespeare or Alexander Pope, after which the planet's other moons are named.

The JWST has made a number of astounding observations into the furthest reaches of our universe. But scientists say this discovery, made as part of the space telescope's General Observer program, highlights the JWST ability to discover things at the outer limits of our own solar system.

"Looking forward, the discovery of this moon underscores how modern astronomy continues to build upon the legacy of missions like Voyager 2, which flew past Uranus on Jan. 24, 1986, and gave humanity its first close-up look at this mysterious world," Maryame El Moutamid, a lead scientist at Southwest Research Institute's Solar System Science and Exploration Division in Boulder, Colorado, said in the statement. "Now, nearly four decades later, the James Webb Space Telescope is pushing that frontier even farther."

Six planets — Mercury, Venus, Jupiter, Saturn, Uranus and Neptune — will appear in a dark night sky together for almost a week, beginning Sunday, Aug. 17. The fairly rare "planetary parade," which is sometimes mistakenly called a planetary alignment, will continue through Wednesday, Aug. 20.

The celestial gathering, last seen in February, will appear in the eastern sky about an hour before sunrise. Although most of these planets have been visible in the morning sky for weeks, Mercury will join the fray, bringing the planet count from five to six.

Under clear skies, you should be able to spot Venus, Jupiter and Saturn. Mercury will be closer to the horizon but still bright enough to be seen by most observers. However, Uranus (appearing between Jupiter and Saturn in the sky) and Neptune (close to Saturn in the sky) are too dim and distant to be seen with the naked eye. The only way to see these two ice giants is by using a good telescope.

Although it's relatively rare for six planets to appear in the sky simultaneously, the beauty of the view will be vastly increased by the waning crescent moon.

Related: How to photograph the moon: Tips on camera gear, settings and composition

On Aug. 17 and Aug. 18, a crescent moon will rise above Jupiter and Venus. The two brightest planets in the night sky are now slowly moving apart after an incredibly close conjunction on Aug. 12.

Mercury may be visible below Jupiter and Venus, but it will be easier to see it on Aug. 19. On that morning, and on Aug. 20, a slim crescent moon will be very close to Jupiter and Venus — a visual highlight of the "planetary parade."

By around Aug. 21, Mercury will begin to fall back into the sun's glare and will become more difficult to see.

According to the Star Walk app, there will be two six-planet parades in 2026: one after sunset in February and another before sunrise in August.

Scientists have found that Uranus is emitting its own internal heat — even more than it receives from sunlight — and this discovery contradicts observations of the distant gas giant made by NASA's Voyager 2 probe nearly four decades ago.

Scientists led by Xinyue Yang of the University of Houston analyzed decades of readings from spacecraft and computer models to find that Uranus emits 12.5% more internal heat than the amount of heat it receives from the sun. However, that amount is still far less than the internal heat of other outer solar system planets like Jupiter, Saturn and Neptune, which emit 100% more heat than they get from the sun.

The researchers behind this new study say Uranus' internal heat could help reveal the origins of the curious, tilted world. "This means it's still slowly losing leftover heat from its early history, a key piece of the puzzle that helps us understand its origins and how it has changed over time," Wang said in a statement.

In 1986, the iconic Voyager 2 probe flew by Uranus while headed out of the solar system and into interstellar space. A good deal of what scientists understand about the seventh planet from the sun comes from that flyby, that found that Uranus does not reveal significant internal heat.

But it turns out that we may have caught Uranus at a weird time, and some of the readings Voyager 2 collected could have been skewed by a surge in solar weather that occurred during its flyby of the planet.

By reviewing a large set of archival data and combining that with computer models, researchers now believe the internal heat emitted by Uranus could imply a completely different internal structure or evolutionary history for the planet we thought we knew. Its believed that Uranus formed around 4.5 billion years ago along with the rest of the solar system, and NASA believes it formed closer to the sun before moving to the outer solar system around 0.5 billion years later. That story, however, is now called into question by these new findings.

"From a scientific perspective, this study helps us better understand Uranus and other giant planets," Wang said in the statement. The researchers also believe this new understanding of Uranus' internal processes could help NASA and other agencies plan for missions to the distant planet.

In 2022, the National Academy of Sciences flagged a mission concept known notionally as Uranus Orbiter and Probe (UOP) as one of the highest-priority planetary science missions for the next decade. But even then, before massive budget uncertainty hit NASA and the science community in the wake of President Donald Trump's overhaul of U.S. government spending, scientists knew such an ambitious and expensive mission would be difficult to put into motion.

"There are many hurdles to come — political, financial, technical — so we're under no illusion," Leigh Fletcher, a planetary scientist at the University of Leicester in the U.K. who participated in the decadal survey process, told Space.com in 2022 when the report was published. "We have about a decade to go from a paper mission to hardware in a launch fairing. There's no time to lose."

Whether or not new research into Uranus helps boost support for such a mission, scientists are already hailing these new results as groundbreaking on their own. Study co-author Liming Li said the study of Uranus' internal heat not only helps us understand the distant, icy world better, but could also help inform studies of similar processes here on Earth, including our own changing climate.

"By uncovering how Uranus stores and loses heat, we gain valuable insights into the fundamental processes that shape planetary atmospheres, weather systems and climate systems," Li said in the statement. "These findings help broaden our perspective on Earth's atmospheric system and the challenges of climate change."

A study on Uranus' internal heat was published in the journal Geophysical Research Letters.

This article was originally published on Space.com.

Astronomers have discovered that the "dark sides" of Uranus' largest moons aren't where they originally thought — and in some cases are on the complete opposite sides of the icy satellites than expected.

Uranus has 28 confirmed moons, including five major moons. The closest of these large satellites is Miranda, followed by Ariel, Umbriel, Titania and Oberon — all named after characters from plays written by William Shakespeare. These icy bodies, which range from 293 to 980 miles (472 to 1,578 kilometers) wide, are all "tidally locked" to Uranus, meaning that the same half of the moon always faces the planet, similar to how Earth's moon orbits our planet.

Because of this tidal locking, the major moons have a "leading side," the hemisphere facing forward in their respective orbits, and a "trailing side," which is always looking back in the satellites' wake. Scientists had assumed that the leading sides of each moon would be brighter when viewed in invisible wavelengths of electromagnetic light, such as ultraviolet and infrared. This is because electrons from the planet's magnetic field, or magnetosphere, should be captured by the moons and naturally accumulate on their trailing sides, scattering radiation and making them appear "darker," similar to some other moons in the solar system.

But in a new study, researchers turned the ultraviolet instruments of the Hubble Space Telescope toward Ariel, Umbriel, Titania and Oberon to measure their brightness. Surprisingly, none of the moons' leading sides were brighter than their respective trailing sides, and on Titania and Oberon, the trailing side was brighter than the leading side, flipping the current theory on its head.

The team shared their findings on Tuesday (June 10) at the 246th American Astronomical Society meeting in Anchorage, Alaska. The results have not yet been published in a peer-reviewed journal.

Related: Scientists finally know how long a day on Uranus is

While the new findings were a shock, they can be partially attributed to confusion around the magnetic properties of the solar system's seventh planet. "Uranus is weird, so it's always been uncertain how much the magnetic field actually interacts with its satellites," Richard Cartwright, a planetary scientist at the John Hopkins University in Maryland and principal investigator of the study team, said in a statement.

Most of this confusion comes from Uranus' unusual tilt. The planet's axis is tilted 98 degrees relative to its orbit around the sun — giving it the appearance of a rolling ball, rather than a spinning top — but its satellites still orbit around its equator, meaning they pass through the magnetosphere at a 59-degree angle. Recent findings also hint that scientists' current assumptions about the magnetosphere's size and strength may be wrong, due to magnetic anomalies that occurred 40 years ago when the Voyager 2 probe took the first up-close measurements of the planet.

The new study does not really help us learn anything about Uranus' magnetosphere because the lack of electrons could be explained by either a weaker magnetic shield or a much stronger and more chaotic one, the researchers said.

However, the unexpected brightness of Titania's and Oberon's trailing sides hint at another unknown phenomenon, which researchers have dubbed "dust shielding." The idea is that little bits of dust around Uranus, which have accumulated over millions of years of meteor strikes on the Uranian moons, are hitting the moons' leading sides "like bugs hitting the windshield of your car as you drive down a highway," researchers said.

"This is some of the first evidence we're seeing of a similar material exchange among the Uranian satellites," added co-investigator Bryan Holler, a support scientist at the Space Telescope Science Institute in Maryland that oversees Hubble's science operations. However, similar exchanges have been observed in the systems of Jupiter and Saturn, he added.

This is not the only surprising discovery made about Ariel, Umbriel, Titania and Oberon. Recent findings have also hinted that all four of these major moons could support or have previously supported subterranean oceans, similar to those believed to exist on Europa, Ganymede and Enceladus.

The researchers hope that the mysteries surrounding Uranus' moons could soon be unraveled by the James Webb Space Telescope, which has already helped uncover many of the planet's secrets using its state-of-the-art infrared instruments.

When you think of a planet with rings, majestic Saturn almost definitely comes to mind. But it's not the only planet in the solar system with these breathtaking bands. So which planets in our solar system have rings?

All four giant planets — Jupiter, Saturn, Uranus and Neptune — sport these spectacular structures. Plus, many other objects in the solar system, including the dwarf planet Haumea and asteroid Chariklo, have rings. Whether or not we can see these rings easily from Earth depends on what they're made of.

Unlike a diamond ring, planets' rings don't last forever — not even the most iconic ones in the solar system. Scientists think Saturn's rings will vanish as the debris that makes up the rings falls into Saturn's atmosphere, but that won't happen for a long time.

"We still have hundreds of millions of years to enjoy them," Saunders said. "But it makes me think about how lucky we are to live at a time when Saturn has beautiful, icy, visible rings."

Every year, Earth follows a familiar pattern of seasonal changes: As summer rolls around in the Northern Hemisphere, winter creeps in in the Southern Hemisphere, and vice versa.

But do other planets have seasonal patterns, too?

Indeed, other planets, dwarf planets and moons in our solar system do have seasonal cycles — and they can look wildly different from the ones we experience on Earth, experts told Live Science.

To understand how other planets have seasons, we can look at what drives seasonal changes on our planet. "The Earth has its four seasons because of the spin axis tilt," Gongjie Li, an astrophysicist at Georgia Tech, told Live Science. This means that our planet rotates at a slight angle of around 23.5 degrees.

So, when Earth is on one side of the sun, the Northern Hemisphere is pointed toward the sun and the Southern Hemisphere is facing away, explained Shane Byrne, a planetary science professor at the University of Arizona. When our planet moves to the other side of the sun six months later, the Northern Hemisphere faces away.

Related: Is Earth the only planet in the solar system with plate tectonics?

Mars has an axial tilt of around 25 degrees. Because this value is so close to Earth's tilt of 23.5 degrees, the amount of seasonal variation on Mars is similar to our planet's.

"Just like on the Earth, you have permanent darkness and permanent daylight at the polar areas, depending on whether you're in the winter or the summer; then you can flip between those two states every half a year," Byrne told Live Science. But interestingly, instead of water-based ice, winters on Mars are dominated by carbon dioxide ice (or dry ice), which can form spidery cracks on the surface on the planet.

In contrast, some planets in our solar system have massively different tilts, leading to more extreme changes throughout the year. For instance, Mercury has no tilt, so "there's almost no seasonal change at all," Byrne said. On the opposite end of the spectrum, Uranus has a 90-degree tilt, so the poles are either completely facing the sun, or not at all, meaning its seasons are intense: Summers are filled with long stretches of constant blazing sun, while winters plunge into perpetual chilling darkness.

But tilt isn't the only factor that drives seasonal changes. The shape of a planet's orbit can also influence seasonal variations in weather. This is because planets' orbits tend to be ellipses, rather than perfect circles. As a result, some planets are sometimes very far from the sun and very close to it at other times. For example, Mercury has an "eccentric" orbit, which contributes to its seasonal variations, Li said. Pluto, too, has a very elliptical orbit that pushes its variations to an extreme, Byrne said.

These two factors — a planet's tilt and the shape of its orbit — can also change over time. Byrne, who studies climate records on Mars, explained that the tilt on the Red Planet wasn't always 25 degrees. In fact, models, published in the journal Earth and Planetary Science Letters in 2018, have shown that Mars's tilt has varied from 10 to more than 40 degrees over the course of billions of years. This has led to extreme fluctuations in the planet's yearly cycle.

"So it's almost just random chance that it happens to be similar to the Earth today," Byrne said.

"On Earth, we're very lucky, this spin axis is quite stable," Li said. Due to this, we've had relatively stable seasonal cycles that have persisted for millennia, although the broader climate sometimes shifts as the entire orbit of Earth drifts further or closer from the sun.

Such stability has likely helped life as we know it develop here, Li said. Scientists like her are now studying planetary conditions and seasonal changes on exoplanets to see whether life could exist in faroff worlds. For now, it seems as though the mild seasonal changes and stable spin tilts on Earth are unique.

Solar system quiz: How well do you know our cosmic neighborhood?

A day on Uranus is about half a minute longer than previously thought, according to new research.

An analysis of 11 years of Hubble Space Telescope observations shows that Uranus' day lasts 17 hours, 14 minutes, and 52 seconds. That's 28 seconds longer than NASA's Voyager 2 spacecraft estimated when it passed Uranus in 1986. Researchers reported the updated estimate April 7 in the journal Nature Astronomy.

Nearly 40 years ago, Voyager 2 became the first spacecraft to observe Uranus up-close. Using radio signals from the planet's auroras and magnetic field data collected by the spacecraft, astronomers at the time found that Uranus' day lasted approximately 17 hours, 14 minutes and 24 seconds.

Researchers used that rotation period to define a coordinate system for the planet. But the measured period came with an inherent uncertainty of about 36 seconds, which gradually added up as each Uranian day passed. Within a few years, the uncertainty made it impossible to accurately determine the orientation of the planet's magnetic axis.

To get more reliable estimates of the planet's rotational period, the authors of the new study tracked the movement of auroras at Uranus' magnetic poles from six sets of Hubble observations taken between 2011 and 2022. This helped them refine the locations of the planet's magnetic poles, which they used to work out a more accurate estimate of Uranus' rotational period. The new measurement has an uncertainty of less than 0.04 seconds, according to the team.

"The continuous observations from Hubble were crucial," first study author Laurent Lamy, an astronomer at the Paris Observatory, said in a statement. "Without this wealth of data, it would have been impossible to detect the periodic signal with the level of accuracy we achieved."

Related: 'Hidden' rings of Uranus revealed in dazzling new James Webb telescope images

The 28-second difference is within the margin of error of Voyager 2's calculation, but the new duration has a much lower uncertainty. "It's not so much that it's changed," Tim Bedding, an astronomer at the University of Sydney in Australia, told New Scientist. "It's now accurate enough to be more useful."

With this smaller uncertainty, the coordinate system based on the new measurement of Uranus' rotational period should hold up for several decades, the team said. Future missions to Uranus, such as the proposed Uranus Orbiter and Probe, could rely on this coordinate system when selecting an atmospheric entry site, the researchers wrote in the study.

"With this new longitude system, we can now compare auroral observations spanning nearly 40 years and even plan for the upcoming Uranus mission," Lamy said in the statement.

Seven planets in the solar system — Mercury, Venus, Mars, Jupiter, Saturn, Uranus and Neptune — will line up in the night sky Friday (Feb. 28) in an incredibly rare "planetary parade."

Although most of these planets have been visible in the night sky since January, Mercury will be joining the procession for just a few days, before Saturn gets lost in the sunset's glare in early March.

Five of these worlds will be easily visible to the unaided eye, but you will need a good telescope to see the full show, according to NASA.

That's because at least two of the planets — Uranus and Neptune — will be too dim to see with the naked eye and will likely be masked by the glare of the setting sun at twilight, NASA said. Saturn will also be trickier to see in some locations due to its position close to the horizon.

If you have a good telescope to catch the full display, the best time to view all seven planets in the Northern Hemisphere will be after sunset on Friday (Feb. 28) at around 8:30 p.m. local time, according to SkyatNightMagazine.

Related: Have all 8 planets ever aligned?

Planetary conjunctions occur when two or more planets appear to be close together in the sky. Of course, this is only from our perspective on Earth; in reality, the planets remain extremely far apart.

Conjunctions happen because the planets of the solar system orbit the sun along roughly the same flat plane as Earth, and they occasionally align when their different orbital distances and speeds bring them into a cluster on Earth's nightside.

These conjunctions aren't rare, but they do get rarer with each planet added to the chain. The three innermost planets — Mercury, Venus and Earth — align within 3.6 degrees in the sky every 39.6 years. For all of the solar system's eight planets to align that closely, it would take 396 billion years — something that has never happened and won't happen before the sun becomes a red giant, consuming Mercury, Venus and likely Earth in the process.

We recommend Time and Date and Stellarium as two great online tools for finding viewing dates and times based on where you are in the world. On mobile phones, Sky Tonight is a free app that will do the same job.

A striking new "planetary parade" photo combines images of six solar system worlds alongside the moon, providing a rare opportunity to compare the sizes of these celestial objects as they currently appear from Earth.

French astrophotographer Gwenaël Blanck created the stunning image by combining individual shots of each of the objects captured Feb. 2 from Paris, where he also took an exceptional photo of Venus and the moon aligning above the Eiffel Tower a day earlier.

The individual images were captured between 6:30 p.m. and 7:50 p.m. local time, using a digital camera attached to a telescope. Blanck then made a composite image of the six worlds in a straight line for the final photo. The objects are arranged from closest to Earth (left) to farthest from our planet (right): the moon, Venus, Mars, Jupiter, Saturn, Uranus and Neptune.

"I had to start quite early, shortly after sunset, to image Venus and Saturn before they were too low on the horizon," Blanck told Live Science in an email. "Neptune was also not far away [from the horizon]," he added. "It was probably the most difficult to capture."

"The Moon, Uranus, Jupiter and Mars were easier to capture, as they were higher in the sky," Blanck said. "The only missing planet was Mercury, which will become visible towards the end of the month and early March."

Related: Have all 8 planets ever aligned?

In reality, the objects in the image were scattered across the night sky. However, Blanck used the same magnification settings for each image, meaning the objects' sizes are perfectly scaled. That is why the moon looks so massive compared with Uranus and Neptune and why Venus and Jupiter appear to be around the same size, despite the latter being more than 10 times wider than the former.

"This gives a pretty good idea of the apparent size of each planet," Blanck said.

Planetary parade

We are currently in the midst of one of the most impressive planetary alignment events in recent years. Under the right circumstances, five planets — Mercury, Venus, Mars, Jupiter and Saturn — will be visible to the naked eye over the next few weeks. Uranus and Neptune are also present in the night sky, but you'll need a good telescope to see them alongside their brighter neighbors.

The event has already delivered some special moments, including an earlier alignment of six of the seven planets in late January and an occultation of Mars by the moon on Feb. 9. However, the parade will not peak until late February and early March, when all seven planets will align in a near-straight line along the horizon, according to Live Science's sister site Space.com.

Venus will be the brightest planet in the night sky during this period; it will be closest to the moon in the sky, making it easy to spot on most clear nights. The "love planet" will reach its peak brightness in time for Valentine's Day (Feb. 14).

If you want to see the best of the planetary parade for yourself, we recommend using a decent telescope or a pair of stargazing binoculars.

The next time we will see a similar alignment of the planets will be in October 2028.

Our understanding of Uranus could have been wrong for nearly four decades, new research suggests — and a weird space weather event is likely to blame.

Much of what we know about Uranus is taken from data gathered by NASA's Voyager 2 spacecraft, which zipped past the ice giant in 1986. The probe's observations revealed the planet had a bizarrely lopsided magnetic field that is misaligned with the planet's rotation and filled with unusually energetic electrons.

But a new analysis of Voyager 2's data revealed the likely cause of the strange readings: a burst of solar wind that whacked the planet's magnetic field out of shape just before the probe flew by. In other words, our understanding of Uranus may be based on an anomalous snapshot in time, rather than the planet's typical nature. The researchers published their findings Nov. 11 in the journal Nature Astronomy.

"If Voyager 2 had arrived just a few days earlier, it would have observed a completely different magnetosphere at Uranus," study lead author Jamie Jasinski, a space plasma physicist at NASA's Jet Propulsion Laboratory (JPL) in Southern California, said in a statement. "The spacecraft saw Uranus in conditions that only occur about 4% of the time."

Magnetic fields form around planets thanks to the churning movement of material inside their molten cores, and they shield planets from jets of plasma known as solar wind that are launched from the sun. When solar particle radiation hits a planet's magnetosphere, it gets trapped by magnetic field lines and is shuffled along it into pockets called radiation belts.

Related: Scientists finally know why ultraviolent superstorms flare up on Uranus and Neptune

It was Uranus's radiation belts — alongside its lopsided magnetic field — that baffled scientists when the first readings from Voyager 2 appeared. The planet's magnetosphere was packed with electron radiation belts second in intensity only to Jupiter. But the rest of the field was devoid of plasma, revealing no apparent source that fed the radiation belts.

The deficit of plasma elsewhere also led scientists to conclude that water ions were not being produced by Uranus' five major moons, four of which are encased in ice. This led astronomers at the time to think that these moons were likely geologically inactive and therefore likely lacked hidden oceans.

By reanalyzing the readings in light of the recorded outburst of solar wind, the researchers behind the new study found that, just before Voyager 2's flyby, the solar wind drove the typical plasma out of Uranus' magnetosphere, knocking it temporarily out of shape and injecting electrons into its radiation belt — similar to how Earth's magnetic field becomes charged-up and warped when hit by intense solar storms.

"The flyby was packed with surprises, and we were searching for an explanation of its unusual behavior," Linda Spilker, a senior research scientist at the JPL who was involved in the Voyager 2 mission, said in the statement. "The magnetosphere Voyager 2 measured was only a snapshot in time. This new work explains some of the apparent contradictions, and it will change our view of Uranus once again."

Over the last few decades, planetary scientists have been steadily adding to the list of moons in our solar system that may harbor interior oceans either currently or at some point in their past. For the most part, these moons (such as Europa or Enceladus) have been gravitationally bound to the gas giants Jupiter or Saturn.

Recently, though, planetary scientists have been turning their attention further afield, towards the ice giant Uranus, the coldest planet in the solar system. And now, new research based on images taken by the Voyager 2 spacecraft has suggested that Miranda, a small Uranian icy moon, may have once possessed a deep liquid water ocean beneath its surface.

What's more, remnants of that ocean may still exist on Miranda today.

When the Voyager 2 spacecraft cruised past Miranda in 1986, it captured images of its southern hemisphere. The resulting pictures revealed a smattering of different geological features on its surface, including grooved terrain, rough scarps, and cratered areas.

Researchers, such as Tom Nordheim, a planetary scientist at Johns Hopkins Applied Physics Laboratory (APL), wanted to explain Miranda's bizarre geology by reverse engineering the surface features, working out what type of internal structures could best explain how the moon came to look like it does today.

The team mapped the moon's various surface features, such as the cracks and ridges seen by Voyager 2, before developing a computer model to test an array of possible compositions of the moon's interior that could best explain the stress patterns seen on the moon's surface.

The computer model found that internal composition that produced the closest match between stress patterns on the surface and the moon's actual surface geology was the presence of a deep ocean beneath Miranda's surface that existed between 100-500 million years ago. According to their models, the ocean may have once measured 62 miles (100 kilometers) deep, buried beneath 19 miles (30 kilometers) of surface ice.

Miranda has a radius of just 146 miles (235 kilometers), which means the ocean would have taken up almost half the moon's entire body. It also means that finding such an ocean is unlikely. "To find evidence of an ocean inside a small object like Miranda is incredibly surprising," Nordheim said in a statement about the new research.

"It helps build on the story that some of these moons at Uranus may be really interesting — that there may be several ocean worlds around one of the most distant planets in our solar system, which is both exciting and bizarre," he continued.

Researchers speculate that the tidal focus between Miranda and other nearby moons were crucial to keeping Miranda's interior warm enough to sustain a liquid ocean. The gravitational stretching and compressing of Miranda, amplified by orbital resonances with other moons in its past, could have generated enough frictional energy to keep it warm enough from freezing over.

Similarly, Jupiter's moons Io and Europa have a 2:1 resonance (for every two orbits Io makes around Jupiter, Europa makes one), which generates enough tidal forces to sustain an ocean beneath Europa's surface.

Miranda eventually fell out of sync with one of the other Uranian moons, nullifying the mechanism keeping its interior warm. Researchers don't think Miranda has fully frozen over yet though, as it should have expanded, causing telltale crack on its surface.

"We won't know for sure that it even has an ocean until we go back and collect more data," Nordheim says.

"We're squeezing the last bit of science we can from Voyager 2's images. For now, we're excited by the possibilities and eager to return to study Uranus and its potential ocean moons in depth."

This new research was published in The Planetary Science Journal on Oct. 15.

Scientists have uncovered the secret ingredient fueling supercharged storms on Uranus and Neptune: methane.

Uranus and Neptune are the outermost planets of the solar system and are known as ice giants because they are rich in water. Scientists understand very little about these distant realms. But after the Voyager 2 spacecraft flew by them in the 1980s, scientists realized that these worlds occasionally host massive, short-lived storms. The violent-but-fleeting storms pop up every few years and are so big you can see them (with a telescope) from Earth.

Researchers have long wondered why the storms on these planets are so unpredictable. Now, a team of astronomers has proposed that methane may hold the key to controlling these storms.

To power a storm, heat must rise from a planet's warm interior to its surface. There, the heated gas begins to cool, which can cause turbulence and trigger storm formation. But the interiors of these planets are always warm, and the outer surfaces are always cool, so why don't storms occur all the time?

In a paper published to the preprint database arXiv on Sept. 3, the team pointed out that methane is the third-most abundant molecule, after hydrogen and helium, in the deep atmospheres of both worlds. Normally, methane doesn't do much except float around in the atmosphere, but the researchers used modeling to show that in certain circumstances, this simple hydrocarbon can dramatically alter heat transfer within the planet.

Methane usually exists as a gas, but in the upper regions of these ice world atmospheres, methane may condense, forming droplets that fall to lower altitudes, the study authors proposed. There they reheat and rise again, completing a cycle similar to the water cycle on Earth. Once the atmosphere becomes too saturated with methane, a stable layer forms. Like a wet blanket, the stable layer keeps heat from reaching the surface, which in turn suppresses storm formation.

These layers are most commonly found throughout all latitudes of Neptune, and around the equator and mid-latitudes of Uranus. But the poles of Uranus don't have enough methane to create a stable saturated layer. As a result,heat can easily rise to the surface and drive larger storms, the study found.

On the other hand, Neptune has more methane overall, and the researchers found that occasionally that methane can rise from the stable layer and disperse through the atmosphere, enabling heat to flow and storms to form, before everything settles down again.

Further work will be needed to understand how all the factors in these ice-giant atmospheres interact

That knowledge could then be used to better understand planets beyond the solar system, the study authors wrote.

Using the James Webb Space Telescope (JWST), astronomers discovered that Ariel, a moon of Uranus, could be hiding in a buried liquid water ocean. 

The discovery could supply an answer to a mystery surrounding this Uranian moon that has perplexed scientists: the fact Ariel's surface is covered with a significant amount of carbon dioxide ice. This is puzzling because at the distance Uranus and its moons exist from the sun, 20 times further out from the sun than Earth, carbon dioxide turns to gas and is lost to space. This means some process must refresh the carbon dioxide at the surface of Ariel.

Previous theories have suggested this happens as a result of interactions between Ariel's surface and charged particles trapped in Uranus' magnetosphere that provide ionizing radiation, breaking down molecules and leaving carbon dioxide, a process called "radiolysis."

However, new evidence from the JWST suggests the source of this carbon dioxide could come not from outside Ariel but from its interior, possibly from a buried subsurface ocean.

Related: James Webb telescope to zoom in on Uranus and Saturn in study of mysterious auroras

Because chemical elements and molecules absorb and emit light at characteristic wavelengths, they leave individual "fingerprints" on spectra. The team behind this discovery used the JWST to gather spectra of light from Ariel, which helped them paint a picture of the chemical makeup of the Uranian moon. 

Comparing this to simulated spectra from a chemical mix in the lab here on Earth revealed to the team that Ariel has some of the most carbon dioxide-rich deposits in the solar system. Not only did this add an extra 10 millimeters (0.4 inches) of thickness to the ice on the side of the tidally locked Ariel that permanently faces away from Uranus, but it also revealed clear deposits of carbon monoxide for the first time.

"It just shouldn't be there. You've got to get down to 30 kelvins [minus 405 degrees Fahrenheit] before carbon monoxide's stable," team leader Richard Cartwright from the Johns Hopkins Applied Physics Laboratory (APL) said in a statement. "The carbon monoxide would have to be actively replenished, no question."

That's because Ariel's surface temperature is, on average, around 65 degrees Fahrenheit (18 degrees Celsius) warmer than this key temperature.

Cartwright acknowledges that radiolysis could account for some of this replenishment. However, observations from Voyager 2's 1986 flyby of Uranus and its moons and other recent findings have suggested that the interactions behind radiolysis could be limited because Uranus' magnetic field axis and the orbital plane of its moons are offset from each other by about 58 degrees.

That means that the majority of the carbon/oxygen compounds seen on Ariel's surface could be created by chemical processes in a liquid water ocean trapped under ice on Ariel.

Cool customer Ariel may have a volcanic temper

Once created in the seep water ocean of Ariel, these carbon oxides could then escape through cracks in the icy shell of the Uranian moon or could even be explosively ejected by powerful eruptive plumes.

Scientists have suspected for some time that the cracked and scarred surface of Ariel may indicate the presence of active cryovolcanoes, volcanoes that erupt plumes of icy slush rather than lava. These plumes could be so powerful that they launch material into Uranus's magnetic field.

The majority of the cracks and grooves seen on the surface of Ariel are located on the side of the moon that faces away from Uranus. If carbon dioxide and carbon monoxide are leaking from these features to the surface of the Uranian moon, this could explain why these compounds are found in greater abundance on this trailing side of the icy body.

The JWST also picked up more chemical evidence of a subsurface liquid water ocean. Spectral analysis hinted at the presence of carbonite minerals, salts created when rock meets and interacts with liquid water.

"If our interpretation of that carbonate feature is correct, then that is a pretty big result because it means it had to form in the interior," Cartwright explained. "That's something we absolutely need to confirm, either through future observations, modeling, or some combination of techniques."

Uranus and its moons haven't been visited by a spacecraft since Voyager 2 almost four decades ago, and this wasn't even the spacecraft's primary mission. In 2023, the Planetary Science and Astrobiology decadal survey emphasized the need to prioritize a dedicated mission to the Uranian system.

Cartwright believes such a mission would present an opportunity to collect valuable information about Uranus and Neptune, the solar system's other ice giant. Such a mission could also deliver vital data about the other potentially ocean-bearing moons of these systems. This information could then be applied to extrasolar planets, or "exoplanets," beyond the solar system.

"All these new insights underscore how compelling the Uranian system is," team member and NASA Applied Physics Laboratory scientist Ian Cohen said. "Whether it's to unlock the keys to how the solar system formed, better understand the planet’s complex magnetosphere, or determine whether these moons are potential ocean worlds, many of us in the planetary science community are really looking forward to a future mission to explore Uranus."

The team's research was published on Wednesday (July 24) in The Astrophysical Journal Letters.

Six of the planets in our solar system — Mercury, Mars, Jupiter, Saturn, Uranus and Neptune — are about to align on June 3 in what some media outlets are dubbing a "parade of planets." The sight is predicted to be best visible an hour before sunrise on June 3 and June 4.

But, despite a flurry of breathless coverage promising otherwise, you won't be able to see all six planets as they rise before dawn. What you can see depends on a variety of factors, including how early you wake up, how much light pollution you have to contend with, and whether you've got a pair of stargazing binoculars or a good small telescope to aid you. 

With that in mind, up to four of the planets on display (Mercury, Jupiter, Uranus and Neptune) may either be too dim to see with the naked eye or masked by the glare of the rising sun, skywatching journalist Jamie Carter wrote for Forbes. 

The remaining planets — Mars and Saturn — will be visible, though they will likely  appear dim in the predawn hours, when the alignment is predicted to occur, Carter added. (Mars and Saturn have actually been visible just before dawn all month long, rising steadily higher each morning in May, Earthsky.com notes.)

Related: Have all 8 planets ever aligned?

However, in a recent video from the National Science Foundation, astrophysicist Joe Pesce paints a more optimistic picture of the alignment.

"It's likely that we'll be able to see Mercury, certainly Jupiter, Mars and Saturn," Pesce said. "Uranus and Neptune are also involved, but you'd need binoculars or a telescope to be able to see those two planets."

Pesce added that the alignment will be visible for a few days before and after June 3, also. And if you don't have a great view of this particular planetary parade, "there's another event in late August, and several predicted for 2025," Pesce said.

All of this means that it may be risky to get up at the crack of dawn to see the upcoming parade of planets, with as many as four of the six planets involved possibly obscured in some way. Take your local weather conditions and light pollution into account before making your plans.

For those who do sacrifice their sleep to catch a glimpse of the alignment, you won’t be entirely let down. That's because on the nights in question, a beautiful crescent moon will be visible near Mars and Saturn, Carter notes.

If you're curious about this alignment, or other upcoming ones, Time and Date and Stellarium are two great online tools for finding viewing dates and times based on where you are in the world, and will even show you the locations of the four hidden planets on June 3. On mobile phones, the Sky Tonight is a free app that will do the same job.

Editor's note: This article was updated on May 31 to include new predictions from the National Science Foundation.

Astronomers have long believed that the ice giants Uranus and Neptune are rich in frozen water. However, a new study suggests they may also have tons of methane ice.

The findings could help solve a puzzle about how these icy worlds formed.

Much about Uranus and Neptune remains unknown. These ice giant worlds have had just a single spacecraft visitor, Voyager 2, which flew past them in the 1980s. As a result, scientists have only a hazy idea of the ice giants' compositions — for example, that they contain significant amounts of oxygen, carbon and hydrogen.

To learn more about what Uranus and Neptune are made of, astronomers have devised models that match the physical properties that Voyager 2 and Earth-based telescopes have measured. Many models assume the planets have a thin hydrogen and helium envelope; an underlying layer of compressed, superionic water and ammonia; and a central rocky core. (The water is what gives them their "ice giant" tag.) Some estimates suggest Uranus and Neptune may each have 50,000 times the quantity of water in Earth's oceans.

But the authors of the new study say these models ignore the way the ice giants formed. As Uranus and Neptune coalesced from the dust cloud surrounding the young sun, they gobbled up, or accreted, objects called planetesimals. The team says these planetesimals resemble present-day comets such as 67P/Churyumov-Gerasimenko, which originate in the Kuiper Belt, the doughnut-shaped region of icy bodies beyond the orbit of Neptune.

Related: Where does the solar system end?

Unlike the supposedly water-rich ice giants, though, a large fraction of these planetesimal-like objects are rich in carbon. So "how is it possible to form an icy giant from ice-poor building blocks?" said Uri Malamud, the study's lead author and a planetary scientist at Technion – Israel Institute of Technology.

To resolve this apparent paradox, Malamud and his co-authors built hundreds of thousands of models of Uranus' and Neptune's interiors. The algorithm they used "starts matching a suitable composition for the surface of the planet, and it gradually works its way deeper into the central point of the planet." They considered several chemicals, including iron, water and methane, the main component of natural gas. Then, they tried to determine which model most resembled the actual ice giants in traits such as radius and mass.

Of the various models they built, the astronomers found that those with methane fit their criteria, with the methane — either in solid chunks or, given the pressure, in a mushy state — forming a thick layer between the hydrogen-helium envelope and the water layer. In some models, methane accounted for 10% of the planet's mass.

The team published their results, which have not yet been peer-reviewed, to the preprint server arXiv in March.

This methane holds the key to resolving the ice paradox. The ice could have formed when hydrogen in the growing planets chemically reacted with the carbon in the planetesimals the planets accreted, the researchers said. Such reactions happen under high temperatures and superhigh pressures — millions of times the air pressure we experience on Earth. These are the exact conditions scientists think existed in the developing planets.

The findings could provide greater insight into these little-understood planets, although verifying if they are actually rich in methane would be challenging, Malamud said. That would be a goal for one of several proposed missions from NASA and other space agencies that aim to explore Uranus.

The James Webb Space Telescope (JWST) is set to begin investigating the spectacular light shows of solar system giants Uranus and Saturn.

Two separate teams of astronomers at the University of Leicester will use the $10-billion space telescope to study auroras over the gas giant Saturn and the frigid ice giant Uranus. The aim will be to explain in greater detail the processes that create these polar light shows over different planets.

"The JWST is already changing how we perceive the universe, from the solar system, our very own cosmic backyard, to the first galaxies formed at the beginning of time," Henrik Melin from the University of Leicester School of Physics and Astronomy who will lead the Uranus investigation, said in a statement. "I am thrilled to have been awarded time on this remarkable observatory, and this data will fundamentally shape our understanding of both Saturn and Uranus.”

Auroras are familiar to skywatchers over Earth as the stunning Northern Lights and Southern Lights, which can be seen along the poles of our planet when they appear.

Related: Astronomers spot aurora on the sun for the 1st time

These light shows are generated over Earth when charged particles that stream from the sun's solar wind strike our planet's protective magnetic field, known as the magnetosphere. These particles travel down magnetic field lines and stream out behind Earth — but, as they do this, they interact with particles in our atmosphere, creating glowing light.

When the sun blasts out high volumes of stellar plasma in so-called coronal mass ejections, auroras are more prominent and can be seen at lower latitudes over Earth.

Though auroras have been seen over other solar system planets before, and they should be possible around any planet with an atmosphere and magnetic field, less is known about these alien light shows.

Currently, relatively little is known about the auroras of Uranus, an ice giant with an atmosphere of water, ammonia and methane.

It was actually only last year, after three decades of investigation, that a research team from the University of Leicester School of Physics and Astronomy — led by Ph.D. student Emma Thomas — confirmed an infrared aurora around Uranus.

Because of a past impact with a roughly Earth-sized body, Uranus is tilted at a 97.77-degree angle. This means that its poles are orientated almost directly toward and away from the sun, and its auroras are positioned around what would normally be the equator for a solar system planet.

As Melin and his colleagues use the JWST to observe the auroras of Uranus, which is the seventh planet from the sun, they will investigate something suggested by this previous discovery of Uranian auroras: Are the auroras of this distant planet responsible for keeping it warmer than expected?

"The temperature of all the gas giant planets, including Uranus, are hundreds of degrees Kelvin/Celsius above what models predict if only warmed by the sun, leaving us with the big question of how these planets are so much hotter than expected," Thomas said last year. "One theory suggests the energetic aurora is the cause of this, which generates and pushes heat from the aurora down towards the magnetic equator."

The JWST study of Uranus will begin early in 2025; it will capture images of the ice giant over a single day for the planet, which lasts around 17 Earth hours. This should allow the team to map auroral emissions across a whole rotation of Uranus' magnetic field.

The scientists will also aim to discover if emissions are produced when the Uranian magnetic field interacts with the solar wind, as happens over the Earth, or if interacting charged particles come from sources within the system similar to how Jupiter creates its auroras. There is also the possibility that Uranus' auroras are created as a combination of these phenomena, just as Saturn's auroras seem to be generated.

The JWST Saturn aurora project, led by Boston University Center for Space Physics scientist Luke Moore, will observe the gas giant's northern auroral region for an entire 10.6-hour Saturnian day. This will allow the team to monitor how the temperature of this region changes as the gas giant rotates.

By revealing Saturn's atmospheric auroral energies for the first time, the team hopes to learn more about the sources of charged particles within the gas giant's atmosphere that drive its auroras.

Both JWST giant planet studies will be conducted using the powerful space telescope's highly sensitive Near-Infrared Camera (NIRCam) instrument.

Once these findings are in hand, scientists can better understand the processes that create auroras in the solar system and the role these mechanisms have on Earth in particular. Perhaps the results can help astronomers glean information about auroras around planet beyond the system too: Extrasolar planets, or "exoplanets."

“A majority of exoplanets discovered so far fall in the sub-Neptune category and hence are physically similar to Neptune and Uranus in size. This may also mean similar magnetic and atmospheric characteristics too," Thomas said. "By analyzing Uranus's aurora, which directly connects to both the planet's magnetic field and atmosphere, we can make predictions about the atmospheres and magnetic fields of these worlds and hence their suitability for life."

Originally posted on Space.com.

As the solar system's planets rove around the sun, sometimes a few will appear to line up in the sky. But have all eight planets ever truly aligned?

The answer depends on how generous you are with the definition of "align" for the solar system's planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

To start with, the orbits of the planets are all tilted to different degrees with respect to the sun's equator. This means that, when planets appear to line up in the sky, in reality they are likely not positioned in a straight line in 3D space, Arthur Kosowsky, an astrophysicist at the University of Pittsburgh, told Live Science.

"The concept of planetary alignment is more about the visual appearance from our perspective on Earth rather than any significant physical alignment in space," Nikhita Madhanpall, an astrophysicist at Wits University in South Africa, told Live Science.

A planetary conjunction is when two or more planets appear close together from our perspective on Earth. It's important to note that the planets are never actually close together. Even when two planets appear lined up to a person on Earth, they are still extremely far apart in space, The Planetary Society notes.

Related: Which planet is closest to Earth? (Hint: There's more than 1 right answer.)

The definition of how close the planets can appear to be considered aligned is not well defined, Wayne Barkhouse, an astrophysicist at the University of North Dakota, told Live Science. Any such definition would involve "angular degrees," the way astronomers measure the apparent distance between two celestial objects in the sky.

If you measured the distance around the circle of the entire horizon, that would equal 360 degrees. To give an idea of the horizon's enormity, the full moon appears only half a degree across, according to Las Cumbres Observatory in Goleta, California.

In the book "Mathematical Astronomy Morsels" (Willmann-Bell, 1997), Jean Meeus, a Belgian meteorologist and amateur astronomer, calculated that the three innermost planets — Mercury, Venus and Earth — "line up within 3.6 degrees on average every 39.6 years," Barkhouse said.

Lining up more planets takes time. According to Meeus, "all eight planets will line up within 3.6 degrees, for example, every 396 billion years," Barkhouse said. "Which means it has never occurred and will not occur, since the sun will transform into a white dwarf in roughly 6 billion years from now. During this process, the sun will become a red giant and expand in size to swallow both Mercury and Venus, and probably the Earth as well. Thus, only five planets will remain in our solar system."

The chances are worse for all eight planets aligning within 1 degree of sky. According to Meeus, "this will occur, on average, every 13.4 trillion years," Barkhouse said. In comparison, the universe is about 13.8 billion years old.

If you consider the eight planets aligned if they are in the same 180-degree-wide patch of sky, the next time that will happen is May 6, 2492, according to Christopher Baird, an associate professor of physics at West Texas A&M University. The last time the eight planets were grouped within 30 degrees was Jan. 1, 1665, and the next time will be March 20, 2673, according to the National Solar Observatory's facility at Sacramento Peak, California.

Madhanpall noted that planetary alignments have virtually no significant physical effects on Earth. "The only impact to life on Earth during an alignment is the wonderful display visible in the sky," Barkhouse added. "There is no danger of enhanced earthquakes or anything like that. The change in the gravitational force that the Earth will experience due to any planetary alignment is negligible."

The solar system just got three new official residents — a trio of tiny moons, one of which orbits Uranus and two more that circle Neptune.

The three moons were all spotted several years ago but were recently confirmed by the International Astronomical Union's (IAU) Minor Planet Center — the organization responsible for naming new solar system objects such as moons, asteroids and comets. The new trio, which have been given numerical designations, will be given formal, literature and mythology-inspired names in the coming years.

Uranus' new moon, S/2023 U1, is only around 5 miles (8 kilometers) across, making it one of the smallest known moons around any of the eight planets in the solar system, alongside Mars' minute companion Deimos. The diminutive moon, which takes around 680 days to orbit around Uranus, brings the planet's total moon count to 28. Like the other Uranian moons, S/2023 U1 will eventually be named after a character from the plays of William Shakespeare, joining the likes of previously discovered moons such as Titania, Oberon and Puck.

Neptune's new satellites, S/2002 N5 and S/2021 N1, are around 14.3 miles (23 km) and 8.7 miles (14 km) wide respectively. S/2021 N1 takes around 9 years to orbit Neptune, while S/2002 N5 takes almost 27 years to orbit the furthest planet from the sun, which now has 16 known moons. Like other Neptunian moons, the newly recognized bodies will be named after the Nereids — the daughters of the sea god Nereus from Greek mythology.

The new moons were each spotted using ground-based telescopes, which is no mean feat considering their diminutive size and distance from our planet.

"The three newly discovered moons are the faintest ever found around these two ice giant planets using ground-based telescopes," Scott Sheppard, an astronomer at the Carnegie Institution for Science in Washington D.C. who was involved in all three discoveries, said in a statement. "It took special image processing to reveal such faint objects."

Related: 10 out-of-this-world solar system discoveries made in 2023

The new moons are so small and far away that their movements are normally too small to be noticeable in most ground-based images of Uranus or Neptune, especially compared to distant stars and galaxies in the background. To counteract this problem, the astronomers took long exposure images and stacked them together to create images where background objects, such as stars and galaxies, became blurred. This stacking made objects with relative motions to each planet stand out much more clearly.

This technique allowed the astronomers to "bring the moons out from behind the background noise in the images," Sheppard said.

The new trio aren't the only moons recently discovered around solar system planets. In February 2023, the IAU confirmed 12 new moons around Jupiter, bringing its total to 92 — the highest total of any planet at the time. But in May last year, the IAU confirmed a whopping 62 moons around Saturn, bringing its total to 145 and wrestling the title of most satellites back from Jupiter. A majority of these new moons, which mostly spanned just a few miles across, were also discovered using Earth-based telescopes.

The recent discoveries demonstrate how new techniques, such as the image stacking, and more powerful ground-based telescopes are allowing researchers to peer even further and with greater clarity into the outer reaches of our cosmic neighborhood.

The solar system ice giants Neptune and Uranus have finally revealed their true colors — thanks to images collected by Voyager 2 three decades ago that have been polished with data from the Hubble Space Telescope and the Very Large Telescope (VLT).

Neptune was previously thought to be a dark azure, while Uranus was supposedly a lighter blueish-green. However, the polished images reveal the ice giants are much closer in color to each other and are actually a lighter blue-green hue.

The images of Uranus, the seventh planet from the sun, and Neptune, the eighth planet, were collected in 1986 and 1989, respectively, as NASA's Voyager 2 spacecraft headed out of the solar system. A team of researchers recently reprocessed  the images, which were published Thursday (Jan. 4) in the Monthly Notices of the Royal Astronomical Society.

Related: Spiral galaxies like the Milky Way are surprisingly rare. Astronomers may finally know why.

"Applying our model to the original data, we have been able to reconstitute the most accurate representation yet of the color of both Neptune and Uranus," lead study author Patrick Irwin, a planetary physicist at the University of Oxford, said in a statement.

How Neptune and Uranus hid their true colors

Scientists knew the ice giants likely looked different than images suggested.That's because when missions like Voyager 2 — thus far the only spacecraft to visit the ice giants — observed Uranus and Neptune, they did so in single wavelengths of light at a time. As a result, all images of them were composites built from several single-color observations of the planets.

These composite images weren't always well-balanced enough to paint a true picture of the planets' colors. This was especially true in the case of Neptune. The contrast in many images of Neptune was enhanced to enable scientists to better see the bands that stretch across the ice giant, as well as its clouds and storms.

"Although the familiar Voyager 2 images of Uranus were published in a form closer to 'true' color, those of Neptune were, in fact, stretched and enhanced, and therefore made artificially too blue," Irwin said. "Even though the artificially saturated color was known at the time amongst planetary scientists — and the images were released with captions explaining it  —  that distinction had become lost over time."

Neptune is "less blue" now thanks to Hubble

To obtain true-color images of Neptune and Uranus, Irwin and colleagues turned to data collected by the Hubble Space Telescope's Imaging Spectrograph (STIS) and Wide Field Camera 3 (WFC3). The team also used data gathered by the Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT) located in the Atacama Desert of northern Chile.

In the images taken by these instruments, each pixel is a continuous spectrum of colors, meaning the data they collected could be used to rebalance the composite images built by Voyager 2.

The results showed that both ice giants are a similar icy cool greenish blue, though Neptune is slightly bluer. The scientists think this is the result of Neptune having a thinner layer of haze surrounding it than Uranus does.

The research also explains why Uranus changes color slightly during its 84-Earth-year orbit of the sun. Previous observations showed that the ice giant appears a touch greener during its summer and winter solstices, when one of its poles is pointed towards the sun, than during its equinoxes, when the sun is above the ice giant's equator.

Irwin and colleagues think this is the result of a "hood" of icy methane increasing the reflection at green and red wavelengths at Uranus' poles. This hood is absent at the equator.

"This is the first study to match a quantitative model to imaging data to explain why the color of Uranus changes during its orbit," Irwin said. "In this way, we have demonstrated that Uranus is greener at the solstice due to the polar regions having reduced methane abundance but also an increased thickness of brightly scattering methane ice particles."

Heidi Hammel, vice president for science at the Association of Universities for Research in Astronomy (AURA), said the new images address lingering ice-giant puzzles.

"The misperception of Neptune's color, as well as the unusual color changes of Uranus, have bedeviled us for decades," Hammel said in the statement. "This comprehensive study should finally put both issues to rest."

What it is: Uranus and 14 of its 27 moons

When it was taken: Dec. 18, 2023

Where it is: 1.8 billion miles (2.9 billion kilometers) from the sun

Why it's so special: This photo of Uranus, captured by the James Webb Space Telescope, reveals the ice giant planet in exquisite detail. The wide-field image shows Uranus' rings, a polar ice cap, 14 of the planet's 27 moons, background stars and galaxies.

The close-up image, snapped by JWST's Near Infrared Camera and released by NASA this week, is a follow-up to a set of photos taken in February. The new image features an extra wavelength of light, revealing a hidden ring. Although Uranus is known to have 13 distinct inner and outer rings, NIRCam revealed the planet's elusive "Zeta ring," a faint, diffuse ring nestled close to the planet.

Of Uranus' 27 moons, 14 are featured in this image: Oberon, Titania, Umbriel, Juliet, Perdita, Rosalind, Puck, Belinda, Desdemona, Cressida, Ariel, Miranda, Bianca and Portia.

It's a much more detailed view of Uranus than humankind's first close-up of the seventh planet, taken by NASA's Voyager 2 probe in 1986. That featureless image showed a solid bluish orb with no detail. JWST, by contrast, has captured atmospheric features such as a north polar cloud cap. That growing and receding cap is fascinating to planetary scientists because it's visible evidence that Uranus spins on an axis tilted by 98 degrees, producing seasonal and meteorological effects that create storms.

Uranus takes 84 Earth years to orbit the sun once. That slow orbit, plus the extreme tilt of Uranus, means the ice giant experiences extreme seasons, with the polar cap visible in the image resulting from its north polar region being in the depths of a 21 Earth-year-long winter that will end in 2028.

Dozens of background galaxies are visible in this wide-field image. Most have an orange tint, but if you look to the right of Uranus, you'll see two sizable white spiral galaxies.

In October, scientists at the University of Leicester in the U.K. published a paper in the journal Nature Astronomy revealing the presence of infrared aurorae around Uranus.

In April 2022, a Decadal Survey report by the National Academy of Sciences recommended that NASA probe the atmosphere, clouds and storms of the turquoise planet as part of the Uranus Orbiter and Probe Flagship mission.

Every year, we learn more about the intricacies of the solar system, and 2023 has been no different. This year, scientists shed more light on our cosmic neighborhood with some intriguing discoveries. From shrinking planets and new moons to an icy supervolcano and mysterious spots, here are the 10 wildest things we learned about the solar system in 2023. 

Mercury is shrinking 

Starting with the planet closest to the sun, Mercury, an October study revealed that the solar system's tiniest planet might be getting even smaller.

Experts have long known that Mercury has shrunk significantly since it first formed. Giant cracks, known as scarps, on the planet's surface were created as the planet contracted over long periods of cooling. 

Scientists originally thought these scarps were billions of years old, but the new research showed that some were just 300 million years old, which suggests the planet has been shrinking for most of its life — and it could still be happening today. 

This year, scientists also discovered that salty glaciers in some of Mercury's craters could provide the necessary conditions for some extreme life-forms to thrive.

Oxygen found on Venus 

Moving farther from the sun, researchers announced in November that oxygen had been detected in Venus' atmosphere for the second time, confirming that the element is present on the hellish planet. 

The thin layer of molecular oxygen (unbonded oxygen atoms) was spotted by NASA's Stratospheric Observatory for Infrared Astronomy, a telescope attached to a large plane that flew above most forms of interference in Earth's atmosphere between 2014 and 2022.

However, this oxygen is not a sign of life on Venus. Instead, researchers suspect the gas is created as solar radiation breaks down carbon dioxide and carbon monoxide molecules in the atmosphere. This oxygen would also be useless to future human colonists because it is not breathable and is found in low concentrations.

This year, scientists also discovered that Venus has thousands more volcanoes than we previously realized and that a majority of them could still be active.

The moon is older than we thought 

Closer to home, a study published in October revealed that the moon may be at least 40 million years older than we previously thought.

Researchers examined tiny impact crystals, known as zircon crystals, within lunar rock samples brought back by NASA's Apollo 17 mission. The new analysis revealed that these crystals,which were left by a colossal collision between Earth and a Mars-size planet that birthed the moon, were older than similar crystals found in other lunar samples.

"These crystals are the oldest known solids that formed after the giant impact," the researchers wrote, and they act as "an anchor for lunar chronology."

This year, astronomers also detected a mysterious heat-emitting blob on the moon's far side and spotted a separate chunk of the moon orbiting Earth.

Mars is spinning faster and faster

One of the biggest stories to come from Mars this year is that the Red Planet's spin has been getting quicker every year, and scientists don't know why.   

Data from NASA's InSight mission shows that Mars' rotation is accelerating at a rate of 4 milliarcseconds per year, which means its days are growing slightly shorter. (A milliarcsecond is one one-thousandth of an arcsecond, which is a unit of angularity.)

Two leading theories explain the speed-up. The first is that ice accumulation at the planet's poles is causing a slight change in how its mass is distributed, and the second is a phenomenon called postglacial rebound, where landmasses rise up after millennia buried under ice.

This year, scientists also solved the mystery of the planet's largest-ever "marsquake" and calculated the minimum number of people needed to start a Martian colony.

Jupiter has a dozen new moons 

This year, scientists confirmed the existence of 12 new moons around Jupiter, bringing the planet's satellite count to 92. At the time, this set a new solar system record.

The newly discovered Jovian moons are small, ranging from 0.6 to 2 miles (1 to 3.2 kilometers) wide, and most of them have wide orbits — nine of the 12 moons take more than 550 days to orbit Jupiter.

The moons were discovered in 2021 and 2022 but were just confirmed this year by the International Astronomical Union's Minor Planet Center.

This year, NASA's Juno spacecraft also discovered organic compounds on the surface of Jupiter's largest moon, Ganymede. The molecules likely came from the moon's subsurface ocean, hinting that it could sustain life.

But Saturn has even more moons

If you thought Jupiter gained lots of moons this year, just wait until you get a load of Saturn's new satellites. This year, scientists officially added 62 moons to the ringed planet's roster, bringing its total to 145 and setting a new record that is unlikely to be broken by Jupiter again. 

Some of the new moons were just 1.6 miles (2.5 km) wide. But all of the newly detected satellites are "irregular moons," meaning they follow distant, elliptical orbits around their host planet and often move in retrograde, meaning in the opposite direction of Saturn's rotation. Some are also clumped together, suggesting they were once a single body that broke apart.

This year, scientists also spotted a key organic compound shooting out of Saturn's icy ocean moon Enceladus, and researchers also worked out that the astronomer who discovered Saturn's largest moon, Titan, was probably nearsighted.  

Polar vortex spotted on Uranus 

Moving into the outer planets, new images of Uranus showed a gigantic "polar vortex" swirling around the ice giant's north pole, suggesting the planet's atmosphere is not as inert as we previously believed.

A polar vortex is a swirling ring of hot or cold air that circles a planet's polar region. These vortices have been spotted on Venus, Earth, Mars, Jupiter, Saturn and Neptune. And in 1986, NASA's Voyager 2 probe spotted a polar vortex around Uranus' south pole on its journey out of the solar system.

The swirling rings are thought to be caused by high-altitude atmospheric jet streams, although the mechanisms differ from planet to planet.

Earlier this year, scientists also spotted a polar vortex on the sun for the first time.

Neptune keeps growing mysterious spots 

This year, astronomers captured the first, clear image of one of Neptune's mysterious dark spots from Earth and photographed a never-before-seen bright spot at the same time.

Temporary dark spots have been documented on the solar system's most distant planet since 1989, when Voyager 2 spotted one as it passed by. Scientists think the dark spots are probably gigantic storms, like Jupiter's "Great Red Spot," but they are unsure why the spots appear so dark. 

The recent bright spot has never been seen before and lasted only a few weeks, so its origins are even more mysterious. But the different spots are likely linked, researchers said.

This year, astronomers also noticed that all of Neptune's clouds had suddenly vanished. The disappearing act is likely linked to a peak in solar activity as the sun reaches the explosive peak in its roughly 11-year solar cycle, known as the solar maximum. 

Pluto has an icy supervolcano 

Demoted planet Pluto has been hiding a gigantic cryovolcano the size of Yellowstone's supervolcano, an October study revealed.

Cryovolcanoes, also known as ice volcanoes, are simply volcanoes that erupt with cryomagma — ice, water and various gases — instead of molten rock. They've been found in several places across the solar system, including the dwarf planet Ceres and at the heart of explosive comets, such as the "devil comet."

Pluto's newly discovered volcano, named Kiladze Caldera, was originally pegged as a crater in images captured by NASA's New Horizons mission. But after taking a second look at the data, scientists detected traces of cryomagama around the depression, which is evidence that it has erupted multiple times.

Scientists don't know if it's still active, but if it is, it could produce enough cryomagma to cover Los Angeles.

Planet Nine might not exist (but it also might) 

Planet Nine is a hypothetical planet that is rumored to exist somewhere in the outer reaches of the solar system.

The Planet Nine hypothesis arose when astronomers detected gravitational anomalies in the Kuiper Belt — a group of comets and asteroids beyond the orbit of Neptune. These anomalies suggest that an invisible planet up to 10 times the size of Earth is lurking beyond the Kuiper Belt.

But in a preprint paper uploaded in September, scientists proposed that these gravitational anomalies could be explained by an alternative theory of gravity, known as modified Newtonian dynamics (MOND). 

MOND suggests that entities toward the edge of the Milky Way, such as the solar system, experience a greater gravitational tug from our galaxy's supermassive black hole heart than traditional gravity allows. Therefore, the Kuiper Belt object may be tugged away by our galaxy and not an elusive planet. However, MOND is not a universally accepted theory, so for now, our best guess is that Planet Nine does exist. 

When you're standing on Earth's surface, it's easy to forget that our planet is hurtling around the sun at more than 67,000 mph (107,800 km/h). And it's even easier to forget that there are seven other planets also making their way around our home star at similar breakneck speeds, or that all eight have been ceaselessly circling the solar system for billions of years. 

But what might really blow your mind is finding out how many trips around the sun each planet has under its belt. This may seem like a tricky thing to calculate, but because the planets' orbits have remained largely unaltered for most of their existence, all it takes is a bit of basic math.

Related: What's the maximum number of planets that could orbit the sun?

The solar system was born around 4.6 billion years ago, when the sun began to form from a cloud of dust left behind by prior stellar explosions. Around 4.59 billion years ago, the giant planets — Jupiter, Saturn, Uranus and Neptune — were born. And around 4.5 billion years ago, the smaller, rocky planets — Mercury, Venus, Earth and Mars — took shape, according to The Planetary Society.

But when the planets were born, their orbits around the sun were not the same as they are today (especially those of the giant planets). For around 100 million years after the first planets formed, there was a "dynamical instability" among them, which resulted in a gravitational tug-of-war between these large bodies and caused the rest of the outer solar system's planetary material, and even some emerging protoplanets, to be catapulted out of the solar system, Sean Raymond, an astronomer at the Bordeaux Astrophysics Laboratory in France and an expert on planetary systems, told Live Science in an email. 

However, once all of the planets had emerged and finished jostling with one another for their positions, they settled into consistent, stable orbits that haven't changed much since.

"For 98% to 99% of the solar system's lifetime, the planets' orbits have been nice and stable," Raymond said. As a result, you can use the planets' current orbital dynamics to make a pretty accurate guess at how many trips they have made around the sun, he added.

Take Earth, for example. Our planet takes a year to orbit the sun and has existed for 4.5 billion years, so it has taken roughly 4.5 billion trips around the solar system. 

However, the number of total orbits varies greatly among the other planets because their years are either shorter or longer than Earth's.

Mercury, the closest planet to the sun, takes only 88 days (or roughly 0.24 years, based on a year with 365.25 days) to travel around the sun once. So, over the past 4.5 billion years, it has completed around 18.7 billion solar orbits. But Neptune, the farthest planet from the sun, takes around 60,190 days (or 164.7 years) to complete an orbit, which means it has managed only about 27.9 million trips around the sun during its 4.59 billion years of existence. That means Mercury has orbited the sun around 18.7 billion times more than Neptune has.

Here is the full list of the planets, their year length and their total number of trips around the sun:

These sound like impressive numbers (and they are) but most of the planets could potentially double their number of orbits in their remaining lifetimes. 

In around 4.5 billion years, the sun will have swollen outward to reach Earth's orbit and transition into a red dwarf star, which will destroy Mercury, Venus and Earth. The other planets may live on for a time if they are not burned up but their orbits will likely be majorly altered.

A vortex of relatively warm air has been detected swirling beneath Uranus' clouds, providing strong evidence for the existence of a cyclone anchored at the planet's north pole. 

The findings add fuel to the fire that Uranus is not as atmospherically inert as it initially seemed when NASA's Voyager 2 spacecraft flew past the "ice giant" in January 1986.

The discovery of a northern vortex on Uranus was made through the detection of thermal emission in the form of radio waves picked up by astronomers using the Very Large Array (VLA) of radio telescopes in New Mexico.

Related: Photos of Uranus, the tilted giant planet

Polar vortices seem to be a common trait of all planets with atmospheres, at least in our solar system – they have been previously observed on Venus, Earth, Mars, Jupiter, Saturn, Uranus (at its south pole) and Neptune. High-altitude atmospheric jet streams are thought to be responsible for the formation of these vortices, although the details differ on each planet.

When Voyager 2 encountered Uranus, it detected changes in wind speeds, which can reach 560 mph (900 kph), at the planet's south pole and which are consistent with the existence of a polar vortex there. However, Voyager 2 did not get a view of the planet's north pole to see if there was a vortex there, too. Compounding this lack of up-close data, observing either of Uranus' poles from Earth has been difficult until recently. This is because Uranus orbits the sun tipped over onto its side by 97.8 degrees. In essence, it is "rolling" around the sun, which meant that for a long time we could only see the planet's equatorial region from our point of view. 

Since 2015, however, Uranus has rolled around the sun enough for us to begin to get a clearer view of its north pole as the planet enters northern spring. In 2018 and 2022, the Hubble Space Telescope observed a bright, smoggy cap over Uranus' north pole — the first evidence for a polar cyclone.

Now, observations of Uranus by the VLA, in 2015, 2021 and 2022, have measured the atmospheric circulation and temperature change in this polar cap. The VLA detected a "dark collar" ringing the planet at 80 degrees latitude, mirroring a bright collar observed by Voyager 2 around its southern pole, which is understood to be a denser part of the atmosphere. Inside this dark collar, the VLA detected a bright spot, indicating temperatures several degrees warmer in the center of the vortex than outside it (where temperatures can drop to minus 370 degrees Fahrenheit (minus 224 degrees Celsius). A bright, warmer spot like this is a very typical characteristic of a cyclone.

"These observations tell us a lot more about the story of Uranus," Alex Atkins of NASA's Jet Propulsion Laboratory in Southern California, who led the observations, said in a statement. "It's a much more dynamic world than you might think."

Unlike Earth's cyclones, Uranus polar vortex is not formed of water vapor but of ices of methane, ammonia and hydrogen sulfide. Nor does the storm drift, instead remaining rooted to the pole. Little else is known about it at this time.

"Does the warm core we observed represent the same high-speed circulation seen by Voyager? Or are there stacked cyclones in Uranus' atmosphere?" wondered Atkins.

In the recent Planetary Science and Astrobiology Decadal Survey issued by the U.S. National Academies, Uranus was highlighted as a priority for a new space mission. To support this goal, planetary scientists are doubling their efforts to study Uranus to help inform the scientific goals of any future mission.

Observing and better understanding Uranus' polar cyclones is a key scientific aim, and Atkins and his colleagues hope to continue studying the north polar vortex for many years to come to observe if and how it might change over time. Already, there are indications that the warm core has begun to brighten as northern spring has progressed.

The results of the VLA observations were published Tuesday (May 23) in the journal Geophysical Research Letters.

Follow Keith Cooper on Twitter @21stCenturySETI. Follow us on Twitter @Spacedotcom and on Facebook.

Originally posted on Space.com.

Hidden oceans may lurk under the icy crusts of four of Uranus' moons. 

Scientists recently reanalyzed data from the Voyager spacecraft that flew by Uranus in the 1980s and found that four of Uranus' largest moons — Ariel, Umbriel, Titania and Oberon — may be warm enough to host liquid oceans. In Titania and Oberon, these oceans might even be warm enough to potentially support life, according to a recent study in the Journal of Geophysical Research. 

"When it comes to small bodies — dwarf planets and moons — planetary scientists previously have found evidence of oceans in several unlikely places, including the dwarf planets Ceres and Pluto, and Saturn's moon Mimas," study lead author Julie Castillo-Rogez of NASA's Jet Propulsion Laboratory in Southern California said in a statement. "So there are mechanisms at play that we don't fully understand."

The new study integrated 1980s Voyager 2 data with information on other icy moons such as Pluto's Charon and Saturn's Enceladus drawn from more recent NASA missions such as Galileo, Cassini, Dawn, and New Horizons. Uranus has 27 moons, but the researchers focused on the five largest, which are Ariel, Umbriel, Titania, Oberon and Miranda. Of these, Ariel is the smallest at 720 miles (1,160 kilometers) across, while Titania is the largest at 980 miles (1,580 km) across. 

Previously, scientists thought only Tatiana was likely to generate any internal heat via radioactive decay — the process by which unstable atoms lose energy through radiation — believing the other moons to be too small. However, modeling the other moons' porosity suggested that all but Miranda are insulated enough to retain internal heat created by radioactive decay. The researchers also found that any potential oceans beneath the icy crusts of these moons would be rich in chlorides, ammonia and salts, both of which would lower the freezing point of the water. The combination of a low freezing point and enough internal heat could mean that Ariel, Umbrial, Titania and Oberon all have oceans dozens of miles deep within their interiors, the researchers reported.

In 2020, scientists detected some evidence of recent geological activity on Ariel, suggesting the possible movement of a potential inner ocean. Miranda also has surface features that look relatively fresh, according to the researchers, but their modeling suggests that if the moon did have a liquid ocean at some point, it is likely frozen by now. 

To find out if these hidden oceans really exist, scientists will have to get creative. Spectrometers that can detect wavelengths of light reflected by ammonia and chlorides could help prove the presence of these chemicals under the crusts. Scientists could also use instruments that can detect electrical currents carried by liquid water to probe beneath these moons' surfaces. New modeling studies on how these moons formed could also help researchers plan what kind of observations they will need to make in the future, Castillo-Rogez said.

"We need to develop new models for different assumptions on the origin of the moons in order to guide planning for future observations," she said. 

Astronomers using the James Webb Space Telescope (JWST) have zoomed in on the faint and dusty rings around Uranus — and they are magnificent.

Located near the frigid edge of the solar system an average of 1.8 billion miles (2.9 billion kilometers) from the sun, Uranus is not often thought of as a ringed world, mainly because the icy planet is far too distant and faint to be seen from Earth with the naked eye. The same is doubly true for Uranus' 13 rings of ice and dust — most of which are so faint that astronomers couldn't confirm their existence until the Voyager 2 spacecraft made a close flyby of the planet in 1986, according to NASA.

Related: 35 jaw-dropping James Webb Space Telescope images

Even through the powerful lens of the JWST — which is already famous for peering across the cosmos into the oldest galaxies and black holes in the universe — only 11 of Uranus' 13 known rings are visible. The planet's two outermost rings are so faint that they were only discovered by the Hubble Space Telescope in 2007, when the planet tilted in such a way relative to Earth that all its rings overlapped, according to NASA. It'll be another few decades before astronomers get another view like that; Uranus is the only planet that rotates on its side, rolling around the sun like a ball once every 84 years. That means Earth only gets to see the rare, edge-on view of Uranus' rings once every 42 years.

Uranus' unique orbit also means that its north pole — seen in this image as a bright region on the planet's right side — experiences many years of direct sunlight, followed by just as many years of total darkness. It's currently spring for Uranus' north pole, with summer scheduled to begin in 2028; meanwhile, the planet's south pole is angled off toward the darkness of space, totally invisible to Earth.

Last September, astronomers turned the JWST toward Neptune — Uranus' neighbor, and the most distant planet from the sun — to reveal that it too is surrounded by shimmering rings that are far too faint to see with the naked eye. 

While they may look sheer and solid in telescope images like these, planetary rings are actually made of billions of fragments of icy rocks, some as large as boulders and others as tiny as dust motes. Scientists aren't sure how planetary rings form, but the process likely began around the same time as the solar system's formation, when our cosmic neighborhood was a chaotic collective of rocky chunks, according to the University of Colorado at Boulder.

Starting this week, you can watch five planets in the evening sky as a crescent moon rises higher each night. 

From Thursday, March 23 through Thursday, March 30, it will be possible to see Mercury, Jupiter, Venus, Uranus and Mars soon after sunset as a waxing crescent moon appears to make a tour of five planets. 

Related: What is the moon phase today?

While Venus and Mars will be very easy to see, you may need to use stargazing binoculars or a telescope to find brightening Mercury and dimming Jupiter, and certainly to see Uranus, which is always just beyond naked-eye visibility. You'll also need a low view of the western horizon, though light pollution makes little difference for planet spotting and moon gazing. 

Planetary parade: What will happen

Over the eight nights, Mercury and Jupiter will swap positions, with the former rising above the latter. But to see the switcheroo, you'll have to be outside, looking low to the western horizon immediately after sunset. Meanwhile, the moon will grow from 7% to 68% lit over the week, rising higher each night to visit a different planet. 

Throughout the week, Uranus will be above Venus in the west, and beyond it, Mars will shine brightly very high in the sky. 

Thursday, March 23: Crescent moon and Venus

On March 23, the view of a slim 7%-lit crescent moon appearing to cup Venus will be jaw-dropping as it hangs just below bright Venus and above Jupiter in the western sky. Mercury will be beneath Jupiter but lost in the sun's glare. Aim some binoculars at the moon, and you’ll see Earthshine, which is sunlight reflected from Earth and back onto the lunar surface, according to NASA. 

Friday, March 24: Crescent moon and Uranus

On March 24, a 13%-lit crescent moon will be above Venus and very close to Uranus. Use binoculars to look for Earthshine on the moon; then range to the left to glimpse the seventh planet. Jupiter will have sunk slightly, and Mercury will have risen, though not enough to be easily visible. 

Saturday, March 25: Crescent moon and the Pleiades

On March 25, the crescent moon, now 21% lit, will be about a third of the way from Venus to Mars. Point some binoculars just above the northeastern limb of the moon, and you'll see the many bright stars of the Pleiades open cluster. 

On Saturday you can also watch live as a skyscraper-sized asteroid zooms between the moon and Earth in a rare, super-close flyby.

Sunday, March 26: Moon and Mars

Now 30% lit, the moon will have moved closer to Mars, while Mercury and Jupiter will be very close to each other low on the western horizon. 

Monday, March 27: Jupiter-Mercury conjunction

Tonight sees a conjunction of the solar system's smallest and largest planets, when Mercury and Jupiter appear to get within about 1 degree of each other and will be visible to the naked eye right after sunset, according to Starwalk. Meanwhile, the 39%-lit moon will shine brightly, close to Mars. 

Tuesday, March 28: Mercury rising

As a half-lit first-quarter moon hangs beyond Mars, Mercury will be rising. On March 28, it will be above Jupiter and more easily visible to the naked eye. 

Wednesday, March 29: Jupiter sinking

As Mercury rises even higher and gets easier to see, Jupiter will be lost in the sun's glare and hard to see. Venus has been rising all week, and now it's getting close to Uranus. 

Thursday, March 30: Venus-Uranus conjunction

As Mercury and Jupiter continue to appear to move in opposite directions, bright Venus will shine just 1 degree from Uranus in the week's second planetary conjunction. However, to see blue-green Uranus, you’ll need to use binoculars or a telescope. 

Depending on where in the world you'll be Wednesday night (Sept. 14), you may be able to see Uranus disappear. (Don't worry; it'll be back again a few hours later.)

On Wednesday, the sixth planet from the sun will appear to pass directly behind Earth's moon, going completely out of sight for three and a half hours. The great disappearing act, also known as the lunar occultation of Uranus, begins around 4:41 p.m. ET (2041 GMT) and ends by 8:11 p.m. ET (0011 GMT on Sept. 15), according to In-the-sky.org. However, only viewers in Europe, northern Africa and western Asia will be at the exact right angle to see the illusion work. 

Viewers in these regions will still need binoculars or a telescope to see the show, as Uranus is not a naked-eye planet. (Check this map, courtesy of In-the-sky.org, to see which regions will have the best view.)

If you are not in one of those places or you don't have a telescope, don't fret; you can watch the occultation live from Rome thanks to the Virtual Telescope Project, which will begin streaming the event at 4:45 p.m. ET (2045 GMT).

Occultation refers to any astronomical event in which one object appears hidden behind another. This phenomenon is slightly different from an eclipse, which occurs when one object casts its shadow directly onto another – such as when the moon's shadow falls over Earth during a solar eclipse.

From Earth, lunar occultations are the most commonly seen, as the moon looms so large in our sky. However, the moon's close proximity to Earth also means that its position in the sky may appear slightly different depending on which part of the planet you're watching from. As such, all lunar occultations are visible only to narrow swaths of the world that happen to have the exact right viewing angle.

Fortunately, these events are frequent, so another lunar disappearing act is always just around the corner. The last lunar occultation of Uranus that was visible from the United States and Canada occurred just last month, on Aug. 18, Live Science's sister site Space.com reported. Uranus emerged triumphant on that night, and it surely will tomorrow, as well.

Originally published on Live Science.

This weekend, Mars and Uranus will appear just two widths of a full moon apart as they go into a rare planetary conjunction in the constellation of Aries.

It's a rare opportunity to see dim Uranus, which is typically hard to find in the night sky, but also to glimpse a brightening Mars. 

Use any pair of binoculars and it will be possible to see both planets in the same field of view. 

The fourth and seven planets from the sun won't really be close to each other. In fact, they'll be about 1.6 billion miles (2.6 billion kilometers) from each other, but in the early hours of Monday, Aug. 1 they will appear just over 1 degree apart in the night sky. 

Related: Dazzling photos of the solar eclipse from Antarctica

When and where to see the Mars-Uranus conjunction

The moment of closest conjunction will vary according to your exact location, but any night this weekend and into early next week will offer spectacular views of Mars and Uranus in conjunction. They will rise together in the east around midnight local time as seen in the Northern Hemisphere and be visible high in the southeast until about two hours before sunrise.

Look around 1:00 a.m. local time where you are, with the very closest conjunctions visible early on Monday (Aug. 1) and Tuesday (Aug. 2).

You should also be able to see the Pleiades — the brightest open cluster of stars in the night sky — close to the two planets.

How to see the Mars-Uranus conjunction

Although it's technically possible for some stargazers to see Uranus with the naked eye under perfectly dark conditions, it's a much better bet to use binoculars or a small telescope. Binoculars will reveal both planets in the same field of view. Mars will appear reddish while Uranus a blue-green hue. 

Another option is to watch a live webcast by the Virtual Telescope Project, which will be broadcasting live views of the Mars-Uranus conjunction through a telescope from Rome, Italy at 9 p.m. EDT on Aug. 1 (01:00 UTC on Aug. 2).

Why Mars is brighter than Uranus

The two planets will not be the same brightness during their conjunction. Mars is gradually brightening in the night sky as it gets closer to Earth and will this weekend it will shine at a magnitude of 0.2, which is about the same as a bright star. It will be about 130 million miles (208 million km) from Earth. That's a lot closer than the much larger ice-giant Uranus, which will be a whopping 2 billion miles (3.2 billion km) distant and will shine at a magnitude of just 5.8. That's right on the limit of naked-eye visibility.

The outer planets and opposition

Mars is now getting brighter because it's waxing toward its opposition, which is when Earth is between a planet and the sun. As a result, that planet looks its brightest and is visible all night. All outer planets from Earth come to opposition in our night sky. Since Mars takes 687 Earth days to orbit the sun — roughly two Earth years — the Red Planet comes to opposition every 26 months. That will next happen on Dec. 8, when Mars will reach a brightness magnitude of -1.9 — about the same as Sirius, the brightest star in the night sky. 

The much slower Uranus, which takes 84 Earth years to make one orbit, comes to opposition once per Earth year. Uranus is next at opposition on Nov. 9, but its massive distance from us means even then it will only shine at a magnitude of just 5.7.

Uranus never gets big or bright for us Earthlings, which is why this weekend's conjunction with Mars is a rare opportunity to find the seventh planet with your own eyes. 

Originally published on Live Science.

If you've been lucky enough to glimpse the northern lights, it's an experience you'll likely never forget. These dancing green, red and purple ribbons of light periodically illuminate the night sky from the Arctic Circle down to mid-northern latitudes as far south as New York and London. Similar lights also occur in the Southern Hemisphere, radiating out from the area around Antarctica.

The eerie glow is a phenomenon called an aurora, named after the ancient Greek goddess of dawn. But the origin of an aurora isn't divine; rather, they are caused by energetic solar winds bombarding Earth's upper atmosphere. As photons from these solar winds interact with atmospheric gases, they light up in brilliant colors and are pulled into fantastic shapes along our planet's magnetic lines. "Oxygen is red and green, and the blue or purple is nitrogen," James O'Donoghue, a planetary scientist at the Japanese Aerospace Exploration Agency (JAXA), told Live Science.

But is Earth the only place in the solar system where you can see auroras?

It turns out that auroras aren't unique to our planet; they exist on other celestial bodies, too. And these extraterrestrial auroras take on even more beautiful and exotic forms. "When you look at other planets, the basic rules get changed," Tom Stallard, a planetary astronomer at the University of Leicester in the U.K. told Live Science.

Related: What color is the sunset on other planets?

For example, a recently discovered type of aurora on Mars (known as a "sinuous discrete" aurora) snakes halfway around the Red Planet, despite the fact that Mars has only patchy magnetic field lines. Some auroras on Saturn are generated by weather patterns, according to 2021 research published in the journal Geophysical Research Letters. And Uranus's magnetic field, like the planet itself, is tilted on its axis, causing auroras to take on intricate shapes and form in unexpected regions. "Yeah, it's a mess over there," O'Donoghue said.

By far the most powerful auroras in the solar system occur on Jupiter. These intense bursts of electromagnetic radiation are up to 30 times stronger than those on Earth, a 2017 study in the journal Nature found. But even with all that energy, you probably wouldn't be able to see Jupiter's aurora with your naked eye — most of its light is emitted in wavelengths outside of the visible spectrum. "Infrared is the biggest emitter on Jupiter and Saturn," O'Donoghue said, "And then after that, you've got visible light, X-rays, and radio as well."

Elsewhere in the solar system, the very definition of an aurora breaks down. Normally, auroras are thought of as the incandescent electromagnetic glow produced by solar wind that occurs in a planet's (or moon's) atmosphere. Mercury has no atmosphere to speak of — but it does experience aurora-producing geomagnetic storms. "If you look at Mercury's night side with an X-ray spectrometer, you see the rock on the surface glowing with X-ray emissions,"  Stallard said, "So that's like a solid state aurora." An X-ray spectrometer detects very high-frequency light waves and is an important tool in astronomy.

Likewise, some of Jupiter's auroras aren't produced by solar winds. Instead, they're generated by particles spewed into the magnetosphere by the planet's volcanic moon, Io, according to NASA.

Now, with next-generation instruments like the James Webb Space Telescope, scientists hope that they may even be able to peer far enough into the universe to detect the first auroras on exoplanets. Nobody knows what these light shows have in store, but it is sure to be spectacular. "Every aurora is interesting and weird and wonderful," Stallard said.

Originally published on Live Science.

Uranus, the seventh planet from the sun, was the first planet to be discovered using a telescope. It is an odd world that tilts over on one side, with thin rings and dozens of moons. 

In 2022, Uranus was selected by planetary scientists as a top target in the solar system for exploration, and NASA expects to launch a new probe sometime in the 2030s, that will explore sideways Uranus in greater detail than ever before. In English, the planet’s name can be pronounced two ways — YOU'-rin-us and you-RAIN'-us. Both invite puerile puns that have made Uranus the butt of schoolyard jokes for generations.

How did Uranus get its name?

In 1781, astronomer Frederick William Herschel spotted Uranus through his telescope, making it the first planet to be discovered in the modern scientific era, according to NASA. Herschel originally thought he was looking at either a comet or a star, but observations by other astronomers, including Johann Elert Bode in the late 1700s, eventually proved it to be a newfound planet. 

The German-British Herschel tried to name the world Georgium Sidus after King George III, but Bode suggested Uranus — the Greek god of the sky — which stuck.

What is Uranus made of?

Like its neighbor Neptune, Uranus is known as an ice giant, meaning 80% or more of the planet's mass is a hot dense fluid composed of icy materials including water, methane, and ammonia, according to NASA. This material isn't ice in the conventional sense; rather, it is more of a compressed slurry, according to Astronomy Magazine. The term "ice giant"” caught on in the 1990s when researchers realized that Uranus and Neptune were compositionally quite different from gas giants Jupiter and Saturn, which are almost entirely made of hydrogen and helium. 

In its innermost parts, Uranus has a small rocky core that heats up to 9,000 degrees Fahrenheit (4,982 degrees Celsius), according to NASA. The extreme temperatures and pressures surrounding the core mean that it is probably enveloped in elements that are compressed into exotic quantum states, and their quantum weirdness transitions into a super-pressurized "soup" that thins out the closer they get to the surface.

Uranus’ atmosphere is mainly hydrogen and helium, with a small amount of methane, which gives the planet its blue color, according to NASA.. In 2021, researchers spotted beautiful infrared auroras in its upper atmosphere. 

Below the upper atmosphere, the planet’s extreme temperatures and pressures rip apart methane molecules and release carbon, which can render into a crystalline form and create diamond rain on Uranus. Stinky mushballs of ammonia may also fall through the planet’s skies when methane breaks down. 

Uranus is slightly larger than Neptune, with a diameter of 31,518.4 miles (50,724 kilometers), but less mass overall, making it the second least dense planet after Saturn, according to NASA. Minimum temperatures on the planet can reach minus 371 F (minus 224 C), meaning it is even colder than Neptune in some places.

How far is Uranus from the sun?

Uranus is on average 1.8 billion miles (2.9 billion km) from the sun, nearly 20 times farther than Earth, according to NASA. Uranus’ year is equivalent to about 84 Earth years, though a single day on Uranus only lasts around 17 hours. 

The system has an extreme axial tilt, with the planet, its rings and moons all tipped over more than 90 degrees relative to the plane of the solar system. Nobody knows exactly how or why this happened, but most astronomers suspect that Uranus was struck by an icy Earth-size object sometime in the distant past.

Have humans explored Uranus?

Only one spacecraft has ever visited Uranus: the Voyager 2 probe, which launched from Earth in 1977 and reached the blue ice giant in 1986, according to the Planetary Society. The robotic emissary came within 50,600 miles (81,500 km) of the planet's cloud tops, discovering 10 new moons, two new rings and a magnetic field stronger than Saturn’s, according to NASA.

In a 2022 decadal survey, in which planetary scientists set priorities in the field for the next 10 years, experts selected a new flagship mission to Uranus as a top science goal, as reported by Live Science’s sister site, Space.com. Researchers are eager to explore Uranus because of its many enigmas, such as the mysterious x-rays that have been seen flaring from the planet, and also because clues about Uranus may inform scientists' understanding of exoplanets, as a large number of recent discoveries are in the same size range as Uranus and Neptune. 

A future Uranus probe would cost around $4.2 billion and would launch in 2031 or 2032 in order to arrive at the planet in 2044 or 2045, according to Space.com. It would orbit the system for several years, studying the planet’s interior, atmosphere and magnetosphere, and touring its intriguing icy moons and thin rings.

How many moons does Uranus have?

Uranus has 27 confirmed moons, according to NASA. All are named for characters from either the works of playwright William Shakespeare or the poet Alexander Pope. In alphabetical order, they are: Ariel, Belinda, Bianca, Caliban, Cordelia, Cressida, Cupid, Desdemona, Ferdinand, Francisco, Juliet, Mab, Margaret, Miranda, Oberon, Ophelia, Perdita, Portia, Prospero, Puck, Rosalind, Setebos, Stephano, Sycorax, Titania, Trinculo, and Umbriel. 

The five largest moons of Uranus are Miranda, Ariel, Umbriel, Oberon, and Titania. Uranus also hosts a delicate ring system. It was first discovered in 1977 when astronomers watched the planet pass in front of a distant star and saw changes in the star’s light that indicated the rings’ presence, according to NASA.

Could there be life on Uranus?

NASA does not consider Uranus to be a place conducive to life as we know it. It’s possible that some of the planet’s larger moons are hiding enormous reservoirs of liquid water beneath their icy surfaces, which could potentially be habitable environments, according to Space.com.

Additional Resources

• Fly around a virtual version of Uranus and its moons using this interactive website from NASA.
• After that journey, you can take a look at some spectacular images of the planet in this NASA gallery, which includes a number of photos captured by the Hubble Space Telescope.
• You can also read an in-depth account of the decision to send a probe to Uranus by browsing the report released by the National Academies of Sciences. 

Astronomers have discovered a perplexing trend in Neptune's atmosphere: Ever since the planet's southern hemisphere summer began almost two decades ago, atmospheric temperatures in this region have plummeted, and scientists aren't sure why.

Neptune is the most distant planet in the solar system, around 30 times farther from the sun than Earth is. Just like every other planet orbiting the sun, Neptune has four distinct seasons: spring, summer, fall and winter. However, because Neptune takes around 165 years to orbit the sun, each of these seasons lasts around 40 years. Neptune's southern hemisphere has been experiencing summer, the period when it is tilted toward the sun, since 2005.

In a new study, researchers compiled infrared images of Neptune taken by a variety of ground and space based telescopes between 2003 and 2020. The team initially expected that temperatures in Neptune's southern hemisphere would increase as it entered summer. However, the images revealed that atmospheric temperatures in the southern hemisphere had dropped by 14.4 degrees Fahrenheit (8 degrees Celsius) between 2003 and 2018.

"This change was unexpected," lead author Michael Roman, an astronomer at the University of Leicester in the U.K., said in a statement. "Since we have been observing Neptune during its early southern summer, we expected temperatures to be slowly growing warmer, not colder."

Related: 'Diamond rain' on Uranus and Neptune seems likely 

Moreover, in the last two years of the study, temperatures around Neptune's south pole rose by 19.8 F (11 C) between 2018 and 2020. The researchers were puzzled by rapid and intense temperature change and cannot explain why this hotspot is bucking the overall trend in the southern hemisphere.   

"Our data cover less than half of a Neptune season," co-author Glenn Orton, a planetary scientist at NASA's Jet Propulsion Laboratory in California, said in the statement, "so no one was expecting to see large and rapid changes."

This is not the first time that Neptune's atmospheric temperatures have perplexed scientists. In 1989, NASA's Voyager 2 probe passed by Uranus and Neptune on its way out of the solar system and found that Neptune was warmer than its closest neighbor despite being farther away from the sun. Scientists have since discovered that this is likely due to gravitational differences between the two planets, Live Science previously reported. 

The researchers don't yet know what is causing the newly detected temperature fluctuations in Neptune's atmosphere, but they offered some potential explanations.

One possible reason is a change in atmospheric chemistry. Neptune's atmosphere is made mainly of hydrogen, as well as helium and methane. The methane gives Neptune and neighboring Uranus their blue color. However, Neptune's striking hues are more intense than those of Uranus, which likely means that another unidentified chemical lurks in Neptune's atmosphere, according to NASA. This mysterious compound or changes in the abundance of other elements could be responsible for these temperature changes, according to the statement. 

Extreme weather could also affect temperatures. Neptune has the strongest winds in the solar system; they can reach up to 1,200 mph (1,931 km/h), according to NASA. These winds push gusts of frozen methane through the planet's atmosphere, potentially affecting the temperature. Neptune also has frequent and massive storms. In 1989, Voyager 2 detected a massive storm near the planet's south pole. At its largest, the storm, known as the Great Dark Spot, was bigger than Earth, and  disappeared in 1994. 

The temperature changes may also result from the solar cycle, the researchers said. Every 11 years, the sun's magnetic field flips, altering levels of solar radiation, which scientists can measure by counting sunspots. There is a loose correlation between the temperature changes and the number of sunspots on the sun over time, but the relationship between the two is not strong enough to conclusively support this idea, according to the new study. 

Continued monitoring by ground-based telescopes and future surveys using NASA's new James Webb Space Telescope could shed light on this phenomenon, according to the statement. But for now, it remains a mystery.  

"I think Neptune is itself very intriguing to many of us because we still know so little about it," Roman said in the statement. "This all points towards a more complicated picture of Neptune’s atmosphere and how it changes with time."

The study was published April 11 in The Planetary Science Journal.

Originally published on Live Science.

The ice giants Uranus and Neptune don't get nearly enough press; all the attention goes to their larger siblings, mighty Jupiter and magnificent Saturn. 

At first glance, Uranus and Neptune are just bland, boring balls of uninteresting molecules. But hiding beneath the outer layers of those worlds, there may be something spectacular: a constant rain of diamonds.

Related: Icy planets' diamond rain created in laser laboratory

"ice giants" may conjure the image of a Tolkien-esque creature, but it's the name astronomers use to categorize the outermost planets of the solar system, Uranus and Neptune.

Confusingly, though, the name has nothing to do with ice in the sense you would normally recognize it — as in, say, ice cubes in your drink. The distinction comes from what these planets are made of. The gas giants of the system, Jupiter and Saturn, are made almost entirely of gas: hydrogen and helium. It's through the rapid accretion of those elements that these huge planets managed to swell to their current size.

In contrast, Uranus and Neptune are made mostly of water, ammonia and methane. Astronomers commonly call these molecules "ices," but there really isn't a good reason for it, except that when the planets first formed, those elements were likely in solid form. 

Into the (not so) icy depths

Deep beneath the green or blue cloud tops of Uranus and Neptune, there's a lot of water, ammonia and methane. But these ice giants likely have rocky cores surrounded by elements that are probably compressed into exotic quantum states. At some point, that quantum weirdness transitions into a super-pressurized "soup" that generally thins out the closer you get to the surface.

But truth be told, we don't know a lot about the interiors of the ice giants. The last time we got close-up data of those two worlds was three decades ago, when Voyager 2 whizzed by in its historic mission.

Since then, Jupiter and Saturn have played host to multiple orbiting probes, yet our views of Uranus and Neptune have been limited to telescope observations.

To try to understand what's inside those planets, astronomers and planetary scientists have to take that meager data and combine it with laboratory experiments that try to replicate the conditions of those planets' interiors. Plus, they use some good old-fashioned math — a lot of it. Mathematical modeling helps astronomers understand what's happening in a given situation based on limited data.

And it's through that combination of mathematical modeling and laboratory experiments that we realized Uranus and Neptune might have so-called diamond rain.

Related: Amazing photos of monster storm in Saturn's atmosphere

It's raining diamonds

The idea of diamond rain was first proposed before the Voyager 2 mission which launched in 1977. The reasoning was pretty simple: We know what Uranus and Neptune are made of, and we know that stuff gets hotter and denser the deeper into a planet you go. The mathematical modeling helps fill in the details, like that the innermost regions of the mantles of these planets likely have temperatures somewhere around 7,000 kelvins (12,140 degrees Fahrenheit, or 6,727 degrees Celsius) and pressures 6 million times that of Earth's atmosphere.

Those same models tell us that the outermost layers of the mantles are somewhat cooler — 2,000 K (3,140 F or 1,727 C — and somewhat less intensely pressurized (200,000 times Earth's atmospheric pressure). And so, it's natural to ask: What happens to water, ammonia and methane at those kinds of temperatures and pressures?

With methane, in particular, the intense pressures can break the molecule apart, releasing the carbon. The carbon then finds its brethren, forming long chains. The long chains then squeeze together to form crystalline patterns like diamonds.

The dense diamond formations then drop through the layers of the mantle until it gets too hot, where they vaporize and float back up and repeat the cycle — hence the term "diamond rain."

Lab-grown diamonds

The best way to validate this idea would be to send a spacecraft toUranus or Neptune. That won't be an option anytime soon, so we have to go with the second-best way: laboratory experiments.

On Earth, we can shoot powerful lasers at targets to very briefly replicate the temperatures and pressures found inside the ice giants. One experiment with polystyrene (aka Styrofoam) was able to make nano-sized diamonds. No, Uranus and Neptune don't contain vast quantities of polystyrene, but the plastic was much easier than methane to handle in the laboratory and, presumably, behaves very similarly.

Also, Uranus and Neptune can keep up those pressures for a lot longer than a laboratory laser, so the diamonds could presumably grow to be a lot larger than nano-sized.

The end result? Based on everything we know about the composition of the ice giants, their internal structures, results from laboratory experiments and our mathematical modeling, diamond rain is a very real thing.

Paul M. Sutter is an astrophysicist at SUNY Stony Brook and the Flatiron Institute, host of "Ask a Spaceman" and "Space Radio," and author of "How to Die in Space."

Learn more by listening to the "Ask A Spaceman" podcast, available on iTunes and askaspaceman.com. Ask your own question on Twitter using #AskASpaceman or by following Paul @PaulMattSutter and facebook.com/PaulMattSutter.

Scientists just squeezed a water droplet between two diamonds and blasted it to star-like temperatures with one of the world's most powerful lasers. The result was a new and mysterious phase of water. 

Called superionic ice, the "strange, black" water exists under the same pressures and temperatures as those at the center of Earth — a fact that could soon help researchers investigate the secrets buried inside the cores of other worlds. 

Previously, researchers used shock waves to create this weird ice for just 20 nanoseconds before it dissolved. This new experiment marks the first time that scientists have created stable superionic ice that lasts long enough to be studied in detail. The researchers published their findings Oct. 14 in the journal Nature Physics. 

Related: Snowflake gallery: No two alike, of course

"It was a surprise — everyone thought this phase wouldn't appear until you are at much higher pressures than where we first find it," study co-author Vitali Prakapenka, a geophysicist at the University of Chicago and a beamline scientist at the Advanced Photon Source at Argonne National Laboratory, said in a statement.

Liquid, vapor and ice are water's most common phases, but water molecules can also settle into other arrangements that represent different phases. In fact, scientists have identified 20 phases of water ice — the different ways that bonded hydrogen and oxygen atoms can stack under varying temperatures and pressures. 

For instance, ice VI and ice VII have molecules that arrange themselves into rectangular prisms or cubes, respectively. Ice XI flips sides if it's placed inside an electric field, and ice XIX is brittle and only has its hydrogen atoms form a regular pattern, Live Science previously reported.

The superhot and highly pressurized superionic ice is the 18th phase of ice to be discovered, and it's one of the weirdest yet. That's because its oxygen atoms lock into place as they would in a solid, but its hydrogen atoms, after giving up their electrons, become ions — atomic nuclei stripped of their electrons and therefore positively charged — that are free to flow through the ice as if they were a fluid. 

"Imagine a cube, a lattice with oxygen atoms at the corners connected by hydrogen," Prakapenka said. "When it transforms into this new superionic phase, the lattice expands, allowing the hydrogen atoms to migrate around while the oxygen atoms remain steady in their positions. It's kind of like a solid oxygen lattice sitting in an ocean of floating hydrogen atoms."

These swimming hydrogen atoms block light from passing through the ice in a predictable way, giving it its black appearance.

A group led by University of Sassari Chemistry professor Pierfranco Demontis first theorized the existence of superionic ice in 1988, and researchers at the Lawrence Livermore National Laboratory in California found the first evidence of it in 2018, Live Science previously reported. By blasting a water droplet with a high-pressure shock wave generated by a laser, researchers achieved the temperatures and pressures required for superionic ice to momentarily appear — and they even measured the ice's electrical conductivity and glimpsed its structure in the few nanoseconds (billionths of a second) before the superionic ice melted away.

To take more detailed measurements, Prakapenka and his colleagues needed to create the ice in a more stable form. So they squeezed their water droplet with a 0.2-carat diamond anvil and blasted it with a laser. The hardness of the diamonds allowed the anvil to pressurize the droplet to 3.5 million times Earth's atmospheric pressure and the laser heated it to temperatures hotter than the surface of the sun. Then, with an electron-accelerating device called a synchrotron, the team launched X-ray beams at the droplet. By measuring the intensities and angles of the X-rays that were scattered by the atoms inside the ice, the researchers identified the superionic ice's structure.

This method gave the researchers a longer time frame — in the microsecond (millionth of a second) range — to observe their ice than the shock-wave experiment had. That extra time meant they could accurately chart the different phase transitions of the water droplet as it morphed into superionic ice.

Further study could help scientists to better understand the ice's properties and map the conditions under which different ice phases occur in nature. Because free-floating hydrogen ions can create a magnetic field, the researchers wonder if superionic ices are buried in the cores of planets such as Neptune and Uranus, or trapped inside the frozen seas of Jupiter's moon Europa, which has an icy crust. If so, the ices could play a key part in the induction of the magnetospheres that surround these worlds, or alien worlds beyond our solar system. As magnetospheres are, in turn, responsible for shielding planets from harmful solar radiation and cosmic rays, knowing how and where superionic ice forms could become an extremely useful guide for scientists searching for alien life.

For now, there are many more properties of the new ice to explore, including its conductivity, viscosity and chemical stability — crucial information for predicting where the weird ice might form elsewhere.

"It's a new state of matter, so it basically acts as a new material, and it may be different from what we thought," Prakapenka said.

Originally published on Live Science.

Scientists have imaged the whole globe of Uranus in the infrared part of the light spectrum for the first time, hoping to shed light on the planet's mysterious auroras and weird magnetic field. 

The British-led team did so during a three-day campaign that was livestreamed publicly last week for the whole world to see. The scientists, based at the University of Leicester in the U.K., used NASA's Infrared Telescope Facility (IRTF) in Hawaii to look at the odd ice giant that orbits the sun 19 times farther away than Earth does. 

Just like on Earth, auroras on Uranus are triggered by the interaction of the solar wind, the stream of charged particles emanating from the sun, with the planet's magnetic field. But because so much is different about Uranus compared to our planet, these auroras behave very differently than the Earth's famous northern and southern polar lights. 

Related: Photos of Uranus, the tilted giant planet 

For example, the axis around which Uranus rotates is nearly perpendicular to the sun. That means the planet essentially rolls around the sun on its side with its poles facing the star nearly directly for an entire quarter of the planet's long year, which lasts 84 Earth years. 

On top of that, Uranus' magnetic poles are not aligned with its geographical poles, like on Earth, Jupiter or Saturn, but are tilted by 60 degrees away from them. As a result, Uranus' auroras don't light up the sky above the planet's geographical poles but at very odd places. 

"The northern aurora actually extends from the northern hemisphere towards the equator, and even dips past into the southern hemisphere," Emma Thomas, an astronomy Ph.D. student at the University of Leicester who led the observations, told Space.com. "If you want to map the aurora, you can't just look at the top of the planet, you have to look across its entire surface."

To image the entire surface of Uranus, the scientists split their observations into three eight-hour windows spread over three days. They had to time each observation window to match Uranus' 17-hour rotation period. Once the data are combined, the result will be the most detailed map of the distant planet's surface in the infrared part of the spectrum. 

"We want to understand where on Uranus are bright parts," Thomas said. "Uranus itself will be illuminated in the current day glow. Anything that is above that level, that's either caused by internal thermal processes or the aurora. By measuring the density of the particles above Uranus, we will be able to tell which one it is."

Previously, the surface of Uranus has only been imaged in the ultraviolet part of the spectrum. NASA's mission Voyager 2 swung past the planet briefly in 1986, taking the first and so far only set of up-close images of the strange planet's surface and the environment around. In 2011, the Hubble Space Telescope for the first time detected auroras glimmering above the surface of Uranus, each covering an area larger than Earth.

But scientists still know very little about these displays and the driving forces behind them, said Thomas. 

"We still don't fully understand the magnetosphere of Uranus and its interaction with the solar wind," Thomas said. A magnetosphere is a region around a planet dominated by its magnetic field. "By mapping the auroras, we can get a better comprehension of the solar wind's interaction with the magnetosphere and from that, we can get a better idea of how the magnetic lines are oriented."

Scientists know that the magnetic field on Uranus behaves in rather strange ways, with magnetic lines frequently disconnecting and reconnecting within a single day, according to a 2017 study. 

Understanding how these auroras vary within a single day could provide new insights into the mechanisms driving this erratic magnetic field, Thomas said. 

The auroras, however, don't vary only with the time of the day but also with seasons of the year, depending which side of the planet is currently illuminated by the sun and which side is submerged in darkness. But as it takes 84 Earth years for Uranus to complete one rotation around the sun, scientists are only very slowly building up their understanding of these seasonal changes.

"At the moment, we have only about a season's worth of data on Uranus," Thomas said. "Everything that we can collect now and in the next 20 and 40 years is really crucial to fully understand how this planet's auroras work."

Follow Tereza Pultarova on Twitter @TerezaPultarova. Follow us on Twitter @Spacedotcom and on Facebook. 

A recent discovery of giant ammonia-rich hailstones, dubbed mushballs, on Jupiter might explain why Uranus and Neptune seem to have no ammonia in their atmospheres. 

Scientists have puzzled for years over the apparent absence of ammonia in the atmospheres of Uranus and Neptune.

Known for its unpleasant smell, ammonia is rather common in the universe. Since the atmospheres of Uranus and Neptune are rich in other chemical compounds known to be present in the primordial cloud from which planets formed, scientists had no good explanation for ammonia's absence in the ice giants' air. 

Related: Could a spaceship fly through a gas giant like Jupiter?

However, a recent discovery of giant ammonia-rich hailstones on Jupiter might shed some light on this mystery. Spoiler alert! The ammonia might not be missing at all; it may just be hidden in deeper layers of the planets' atmospheres, where current scientific instruments cannot reach. 

A possible key to solving this mystery was provided by NASA's Juno mission, which is currently orbiting Jupiter. 

"The Juno spacecraft has shown that in Jupiter, ammonia is present in abundance, but generally much deeper [in the atmosphere] than expected," Tristan Guillot, a researcher at the French National Centre for Scientific Research (CNRS) in Nice, said in a statement.

A study published last year in the journal Nature found that mushballs containing ammonia form high in the atmosphere of Jupiter during thunderstorms thanks to ammonia's ability to melt ice into liquid water even in extremely cold temperatures of around minus 162 degrees Fahrenheit (minus 90 degrees Celsius). 

As these mushballs fall through the atmosphere, they absorb more and more ammonia, eventually accumulating up to 2.2 pounds (1 kilogram) of mass. The ammonia gets transported deep into the atmosphere, where it remains locked below the cloud base. 

"What we have learned at Jupiter can be applied to provide a plausible solution to this mystery at Uranus and Neptune," said Guillot, who presented his theory at Europlanet Science Congress (EPSC) 2021, which was held virtually this year from Sept. 13 to Sept. 24. 

"Thermodynamic chemistry implies that this process is even more efficient in Uranus and Neptune, and the mushball seed region is extended and occurs at greater depths," Guillot added. 

That means that, just like on Jupiter, on Uranus and Neptune ammonia may be simply hidden deep in the atmosphere. Scientists currently measure the atmospheric composition of these distant planets of the solar system by analyzing the infrared and radio signatures of the atmospheres by Earth-based telescopes. 

Both of these planets have so far been visited very briefly by only one spacecraft: NASA's Voyager 2 in the late 1980s. 

The intrigues of the distant planets' atmospheres, Guillot suggests, provide an incentive for a dedicated mission that could enable scientists to fully uncover what's going on.

"To fully understand the processes, we need a dedicated mission to map the deep atmospheric structure and understand mixing in hydrogen atmospheres," said Guillot. "Neptune and Uranus are a critical link between giant planets, like Jupiter and Saturn, and ice giant exoplanets that we are discovering in the galaxy. We really need to go there!"

Follow Tereza Pultarova on Twitter @TerezaPultarova. Follow us on Twitter @Spacedotcom and on Facebook. 

For the first time, astronomers have detected mysterious X-rays flaring out of Uranus.

How is this happening? According to NASA scientists, Uranus is so massive that it could just be scattering X-rays given off by the sun more than a billion miles away. Or, perhaps the fine rings of dust surrounding Uranus are generating their own radiation through some unknown process. A closer study of Uranus is required to know for sure.

Uranus is cold, windy and made almost entirely of ice and gas. Even though it's enormous (with a diameter about four times Earth's), Uranus is difficult to study in depth. Only one spacecraft — NASA's Voyager 2 — has ever made the perilous journey to the planet, forcing scientists to rely mostly on telescope observations much closer to Earth in order to study the ice giant.

In a new study published March 31 in the journal JGR Space Physics, astronomers looked at some archival observations of Uranus taken by NASA's Chandra X-Ray Observatory, an orbiting telescope that scours the universe for sources of X-ray radiation.

According to NASA, X-rays are emitted when matter is heated to millions of degrees, like when stars explode or when matter swirls around the edge of a black hole at near light speed. Until recently, X-ray emissions had been detected from every planet in the solar system except Uranus and Neptune. In most cases, these emissions occur when X-rays created by the sun crash into atoms in a planet's atmosphere, scattering the light back into space.

In the new study, researchers looked at Chandra data taken from Uranus in 2002 and 2017, and saw clear evidence of X-ray emissions in both years. Several of these emissions had a brightness consistent with solar X-rays being scattered back outward, the researchers wrote. However, in the 2017 observations, the team detected a possible "flare" of X-rays, where the brightness of emissions around Uranus increased four times from one day to the next.

According to the researchers, "this may be indicative of additional X‐ray emission processes at Uranus," besides mere solar scattering.

What mysterious phenomenon could be generating the X-rays from Uranus? One possibility lies in the planet's rings. According to the researchers, the environment around Uranus is rich in charged particles such as protons and electrons; these particles could be colliding into the planet's rings, producing X-rays in the process. (A similar phenomenon has been observed in Saturn's rings, the team wrote.)

It's also possible that the X-rays are the result of some sort of auroral process, in which charged particles from the sun are colliding with Uranus' magnetic-field lines and causing a distinct glow. However, further observations are required to flesh out this hypothesis. For now, the X-ray lights of Uranus remain a mystery.

Originally published on Live Science.

Researchers are investigating an alien version of water inside the strange, icy interiors of Uranus and Neptune. 

In a new study, scientists have devised a theoretical computer model and used it to peer inside the ice giants Uranus and Neptune. With this tool, the team studied the thermal and electrical conductivity of the unusual water inside of these planets. In simulating these physical processes on the teeny-tiny atomic scale, the researchers hope that this new model will reveal information about the icy bodies' internal structure, magnetic fields, how they evolved and exactly how old they are. 

In studying Uranus and Neptune with this model, the researchers, who stem from the International School for Advanced Studies (SISSA) in Trieste, Italy and the University of California at Los Angeles, estimated that the two planets are likely primarily composed of water in some form and Uranus might even have a frozen core, according to a SISSA statement. 

Related: What is Uranus made of? 

"Hydrogen and oxygen are the most common elements in the Universe, together with helium. It is easy to deduce that water is one of the major constituents of many celestial bodies," the researchers said in the same statement. 

The team looked at three different phases of water that could exist in these planets interiors: ice, liquid and superionic (superionic water exists at extremely high temperatures and pressures.) But, as the researchers explained in the statement, water on (and inside of) an alien planet is far different from water on Earth. 

"In such exotic physical conditions, we cannot think of ice as we are used to," SISSA professors and study co-authors Federico Grasselli and Stefano Baroni said in the statement. "Even water is actually different, denser, with several molecules dissociated into positive and negative ions, thus carrying an electrical charge. Superionic water lies somewhere between the liquid and solid phases." 

So what did they find about the water inside of these ice giants? The researchers hypothesize, they explained in the statement, that Uranus might actually have a frozen core. This would explain why the planet isn't very luminous, as a frozen core would mean that very little heat would move towards the planet's surface, according to the statement. 

The scientists also found that superionic water in Uranus and Neptune is more electrically conductive than water on Earth, and they think that superionic water could compose a large portion of the dense inner layers of these gas giants. These results further our understanding of exactly how the two bodies are composed and how they came to be, the study suggests. 

As the two scientists said in the statement, "Thermal and electrical conduction dictates a "planet's history, how and when it was formed, how it cooled down. It is therefore crucial to analyze them with the appropriate tools, like the one we have developed."

This work was published July 17 in the journal Nature Communications. 

Email Chelsea Gohd at cgohd@space.com or follow her on Twitter @chelsea_gohd. Follow us on Twitter @Spacedotcom and on Facebook.

Fiery rose and peach sunset skies are a unique perk of our home on Earth. But what colors appear when the sun sets on other planets in the solar system?

The answer depends on the planet. On Mars, the sun comes and goes with a blue glow. On Uranus, the sunset sky transitions from blue to turquoise, according to NASA. And on Titan, one of Saturn's moons, the sky turns from yellow to orange to brown as the sun dips beneath the horizon. 

Sunset colors aren't uniform because, in large part, these hues are a product of each planet's atmosphere and how the particles in it scatter sunlight, according to Kurt Ehler, a professor of mathematics at Truckee Community College in Reno, Nevada, and lead author of a 2014 paper in the journal Applied Optics that investigated why the Martian sunset appears blue. 

Related: Do other planets have solar eclipses? 

"It’s tricky," Ehler told Live Science. "Everyone had a preconceived notion that the mechanism [for sunsets] is a replication of what we see on Earth." But that’s not the case. 

On Earth, the atmosphere is made up of tiny gas molecules, largely nitrogen and oxygen, which are more effective at scattering — that is absorbing and re-emitting in a different direction — short wavelength light, like blue and violet, than it is longer red wavelengths. The selective type of scattering caused by small molecules is called Rayleigh scattering. It gives us a blue sky at midday, but at sunset and sunrise, when the sunlight must travel farther, more of the blue light gets scattered away; it’s the longer red and yellow wavelengths that reach our line of sight, creating the vibrant shades of red that we see. 

Any planet whose atmosphere is dominated by gas will follow a similar pattern of longer wavelength-colors becoming more dominant at sunset, Ehler said. On Uranus, for instance, the gas particles of hydrogen, helium and methane in its atmosphere scatter the blue and green shorter wavelengths while absorbing (but largely not re-emiting) longer red wavelengths, according to NASA. This creates a bright blue sky that turns turquoise at sunset as blue light is scattered away relative to the longer, greenish wavelengths.  

If a planet's atmosphere is dominated by something other than gases, everything about how the sunset appears is going to be different. Take the blue Martian sunset. "The density of atmospheric gas is only about 1/80 of what it is here," Ehler said of Mars. "The scattering is dominated by larger particles of dust." 

In a 2014 study that used data from the Mars rover Spirit, Ehler and his colleagues found that Martian dust scatters light very differently than gas molecules do. "The reason for [the] blue sunset is the pattern in which light scatters off those [dust] particles," he said.

Gas molecules, like the ones here on Earth, scatter light in every direction. In contrast, dust scatters light primarily in one direction — the forward direction, Ehler said. What's more, dust particles scatter red light at much wider angles than blue light does. Because the blue light isn’t scattered very widely, it becomes more concentrated, so "the blue light is about six times as intense as the red light" on Mars, Ehler said. 

Related: How much would you weigh on other planets?

When you look at the Martian sunset, you actually see that "the disk of the sun is white, because light doesn't change color as it passes through the Martian atmosphere," Ehler said "Around the sun there’s a bluish glow. And further out, the sky starts looking reddish. There, you’re seeing red lights scattered at larger angles."  

As for the other planets and moons, it’s nearly impossible to predict how the sunset will look without having a thorough understanding of their atmospheric composition. If these celestial bodies have a gaseous atmosphere, you’d expect to start seeing longer wavelengths of light at sunset, Ehler said. 

"Where [the] atmosphere is dominated by other substances, I can’t tell you," Ehler said.  Different types and size distributions of dust will scatter light in unique ways. In other words, if you think a sunset on Earth is "out of this world," think again — it's really an exclusive feature particular to planets with gaseous atmospheres.

Originally published on Live Science.

The impactor that knocked Uranus on its side long ago isn't quite so mysterious anymore.

Uranus is tipped over more than 90 degrees relative to the plane of the solar system, and so are the gaseous planet's ring system and the orbits of its 27 known moons. Astronomers think this unique configuration is evidence of a violent collision Uranus suffered shortly after it was born, which also apparently supercharged the planet's rotation. (Uranus spins around its axis once every 17 hours, significantly faster than Earth does.)

Details of that collision have remained elusive, however, because simulations have struggled to generate the Uranus system that we see today. For example, the mass of the post-impact debris disk tends to be quite big in these models — much bigger than it "should" be, given the total mass of Uranus' moons today.

Related: How did Uranus form?

Until now, that is. A team of researchers has had success with a novel modeling strategy devised to investigate the formation of moons around frigid planets, a new study reports.

The frigid part is key. Giant impacts in the cold and dark outer solar system have different consequences than smashups much closer to the sun, such as the long-ago collision that resulted in the formation of Earth's moon, the researchers found.

This latter encounter involved the proto-Earth and a Mars-size body called Theia, both of which were primarily rocky (rather than icy). The material blasted into space by the impact therefore solidified rather quickly, allowing the newborn moon to snare quite a bit of it gravitationally.

But the material liberated during the Uranus collision was much more volatile — stuff like water and ammonia — and remained gaseous longer. The growing proto-Uranus gobbled most of this gas up, leaving less of it around to form moons, according to the new study, which was published online last week in the journal Nature Astronomy.

The researchers' model, which takes all of this into account, suggests that the body that slammed into Uranus was icy and big, with a mass between one and three times that of the modern Earth.

"This model is the first to explain the configuration of Uranus' moon system, and it may help explain the configurations of other icy planets in our solar system such as Neptune," study lead author Shigeru Ida, of the Earth-Life Science Institute at the Tokyo Institute of Technology in Japan, said in a statement.

"Beyond this, astronomers have now discovered thousands of planets around other stars, so-called exoplanets, and observations suggest that many of the newly discovered planets known as super-Earths in exoplanetary systems may consist largely of water ice," Ida said. "And this model can also be applied to these planets."

• Photos of Uranus, the tilted giant
• Old gas blob from Uranus found in vintage Voyager 2 data
• How the moon formed: 5 wild lunar theories

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. 

Buried inside data that NASA's iconic Voyager 2 spacecraft gathered at Uranus more than 30 years ago is the signature of a massive bubble that may have stolen a blob of the planet's gassy atmosphere.

That's according to scientists who analyzed archived Voyager 2 observations of the magnetic field around Uranus. These measurements had been studied before, but only using a relatively coarse view. In the new research, scientists instead looked at those measurements every two seconds. That detail showed what had previously been missed: an abrupt zigzag in the magnetic field readings that lasted just one minute of the spacecraft's 45-hour journey past Uranus.

The tiny wobble in the Voyager 2 data represents something much larger since the spacecraft was flying so fast. Specifically, the scientists behind the new research believe the zigzag marks a plasmoid, a type of structure that wasn't understood particularly well at the time of the flyby in January 1986.

Related: Photos of Uranus, the tilted giant planet

But by now, plasmoids have earned scientists' respect. A plasmoid is a massive bubble of plasma, which is a soup of charged particles. Plasmoids can break off from the tip of the sleeve of magnetism surrounding a planet like a teardrop. 

Scientists have studied these structures at Earth and nearby planets, but never at Uranus or its neighbor Neptune, since Voyager 2 is the only spacecraft to date ever to visit those planets.

Scientists want to know about plasmoids because these structures can pull charged particles out of a planet's atmosphere and fling them into space. And if you change a planet's atmosphere, you change the planet itself. And Uranus' situation is particularly complicated because the planet rotates on its side and its magnetic field is skewed from both that axis and the plane all the planets lie in.

Because Voyager 2 flew straight through this plasmoid, scientists could use the archived data to measure the structure, which they believe was about 250,000 miles (400,000 kilometers) across and could have stretched 127,000 miles (204,000 km) long, according to a NASA statement.

Ideally, scientists would piece together more observations of Uranus' magnetic field, enough to better understand how this phenomenon has shaped the planet over time. But that will require another spacecraft visit the strange sideways world.

The research is described in a paper published in August in the journal Geophysical Review Letters. NASA announced the finding on Wednesday (March 25).

•  Uranus may have odd, strobe-like magnetic field 
•  Why is Uranus on its side? Incredible simulations could solve the mystery. 
•  How did Uranus form? 

Email Meghan Bartels at mbartels@space.com or follow her @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook. 

When Voyager 2 reached Neptune in 1989, just 12 years after setting off on its historic journey through the solar system, it discovered six new moons, took the first images of the planet's rings and noted a particularly violent storm.

The storm was something of a surprise. In the southern hemisphere there was a swirling, counter-clockwise wind of up to 1,500 mph (2,414 km/h) — the strongest ever recorded. Astronomers called it the Great Dark Spot, and while it had gone by the time the Hubble Space Telescope looked at the planet five years later, they were keen to learn why the winds were so extreme.

Related: The 12 Strangest Objects in the Universe

They were also perplexed by another issue: Voyager 2 revealed that Neptune is warmer than Uranus, despite being farther from the sun. As physicist Brian Cox discussed in his BBC documentary, The Planets: "The source of this extra heat remains a mystery." But does that mean we have a double-puzzle on our hands, and can one mystery help to explain the other in some way?

Before we begin to address the two issues at hand, we must first look at what is actually meant by "warmer." Since Neptune is a gas giant, we cannot test the globally average temperature at ground level in the way that we could on the solid surface of Earth. Instead, with Neptune's core likely to be small, temperature measurements must be taken at an altitude. Trouble is, which one?

The trouble with temperature

"We can only measure temperatures in the outermost layers," said Michael Wong, a planetary scientist at the University of California, Berkeley, via email. In doing so we find that Neptune isn't actually hotter than Uranus in real terms — they're essentially at the same temperature. But since Neptune receives less solar illumination because it's farther from the sun, this shouldn't be the case.

What this similarity in temperature suggests is that Neptune is warmer in terms of how much heat it emits in comparison to the amount of heat it absorbs from the sun. "Voyager's measurements show Neptune emits more than twice as much heat as it absorbs from the sun, while Uranus does not," Anthony Del Genio of the NASA Goddard Institute for Space Studies (GISS) told All About Space. And this is where things become rather intriguing.

That's because Neptune is not unusual in this case. "Jupiter and Saturn also emit almost twice as much heat as they absorb, but Uranus does not," Del Genio said. "Uranus is the oddball." 

Related: How Did Uranus End Up On Its Side?

"The progression of temperature as you go farther away from the sun shows Jupiter to be the warmest of the gas giants, Saturn next, then Neptune. Uranus is the one that is out of place," Del Genio said. "Yet that unusual result is associated with the fact that Uranus does not have a significant internal heat source." Neptune is finding a way to warm itself up to the level of Uranus, while the latter is unable to generate any extra heat other than that gleaned from the sun.

But just what is an internal heat source? In simple terms it is heat left over from the birth of the solar system when these planets were formed. The heat contracts out of the primitive solar nebula — an effect known as the Kelvin-Helmholtz contraction.

"The extra heat source on Neptune [and Jupiter and Saturn] is largely due to gravitational contraction," said Joshua Tollefson, also of the University of California, Berkeley. "As the planet slowly gravitationally contracts, the material falling inward changes its potential energy into thermal energy, which is then released upwards out of the planet."

Yet there is no clear reason why Uranus does not have much of an internal heat source — or any at all. "Something must have stunted this process on Uranus — perhaps due to a collision in its early history that knocked the planet on its side," said Tollefson. "The question becomes, why does Neptune have an internal heat source but Uranus does not?"

Frozen planets that love to burp

There is a possibility that heat is not released from the interior at a steady rate but instead comes in "burps". "We may just be seeing Uranus in a quiescent period, whereas Neptune has burped more recently," said Tollefson. "The burps are convection, which may happen in discrete episodes separated by long time periods, but we may not know if it works this way for sure unless we see one of these convective episodes take place."

It could also be an issue of Uranus being an old-timer and Neptune a younger pup. "How much heat a planet radiates depends mostly on how old it is and how quickly or slowly it releases that heat," said Amy Simon, a NASA senior scientist for Planetary Atmosphere Research at the NASA Goddard Space Flight Center. "An older planet would be colder. How quickly they release depends on the interior structure and composition, cloud layers, convection and so on and that can be rather complicated."

Related: 10 Interesting Places in Our Solar System We'd Like to Visit

"On the gas giants there may be significant amounts of helium rain, changing the amount of heat released. For Uranus and Neptune it is possible that they are different ages or, more likely, the event that turned Uranus onto its side may have jumbled its interior structure and/or released heat faster," said Simon.

So what of those winds? They are undeniably fierce, and this may have something to do with temperature.

"We've speculated for a long time that the coldness of Neptune and Uranus might lead to near-frictionless conditions and so allow for faster winds," said Heidi Hammel, a planetary astronomer who has studied both planets extensively and who was part of the team imaging Neptune from Voyager 2.

By this she means there are no mountains, hills or other shapes across the Neptunian landscape slowing the winds. But is there any relation between the storms and the internal heat source? "Probably," said Hammel, "but there is also some delicate balance between the internal heat and the incoming sunlight."

It is difficult to quantify these effects because of the long timescales involved. "One year on Neptune is 165 Earth years so we have not had a chance to study the planet with modern tools for very much of its seasonal cycle," said Hammel. "You need a lot of patience — and trust in past and future generations of planetary scientists — to study the atmospheres of outer planets."

"I guess the theory was supposed to be the greater amount of solar energy, the more wind energy, but on Earth we've known for a long time that the amount of energy received by the sun and converted into kinetic energy in the atmosphere — that is, wind — is a tiny fraction,” said Del Genio.

Earth is a very inefficient heat engine, and it doesn't give you much bang for the buck. One reason is that it has a solid surface that dissipates wind energy by friction, whereas the gas giants do not, so that is one reason why all the giant planets have much stronger winds than Earth does.

Why are Neptune's winds so strong?

"Winds are probably generated deeper than sunlight can penetrate, so a combination of internal heat and rotation likely produces them," said Simon, raising the issue of why Uranus and Neptune's winds don't match, given they have similar rotation rates. "It tells us something is different between them: partially internal heat or something else," said Simon.

Uranus' winds can blow up to 560 mph and Neptune's 1,500 mph. "They're both extremely fast and peak at speeds faster than Jupiter," said Tollefson. NASA says Jupiter's Great Red Spot can blow at 384 mph. But he too says internal heat alone cannot explain the speeds, given Uranus does not generate extra heat.

The interior structure of the planets — their masses, core sizes and radial density profiles — is extremely important for understanding the winds as we see them. How the winds form and how deep they go are questions currently being answered for Jupiter and Saturn thanks to NASA's Juno and Cassini spacecraft. This is due to the extremely good gravitational data they've obtained, which means good models for the interior structure can be made.

Related: Jupiter's Great Red Spot: Our Solar System's Most Famous Storm

Computer simulations suggest that the winds of the ice giants are confined to shallow depths in the upper layers of their atmospheres. This may suggest that the fast winds we see on Uranus and Neptune are at least partly due to the latent heat release of condensation for materials like water.

Del Genio also questions the available data. He explains that when we measure winds on Neptune, we look at one specific altitude. "The winds at other altitudes may be slower or faster," said Del Genio. "We don't know because we have never dropped probes into the atmospheres of most of the outer planets."

What Neptune and Uranus show is that planets which form in similar conditions can provide two extremes. Simon says this helps us constrain models of how these planets form and give clues about the solar system's overall formation. "They should also help us better understand deeper circulation, given they are so far from the sun."

"It adds to our knowledge of the physics and chemistry in planetary atmospheres and helps us understand our own Earth a little better, since the physics and chemistry operate in the same way whether here on Earth or on distant Neptune," said Hammel.

Additional resources:

• The Greatest Mysteries of Neptune
• 11 Fascinating Facts About Our Milky Way Galaxy
• The 9 Most Intriguing Earth-Like Exoplanets

Uranus is a weirdo — the icy giant rotates while lying on its side and it's been called a rear end in even the highest echelons of academia (right?). Now, astronomers have found it has an oddball ring system, too.

In new images of the rings around Uranus (the seventh planet from the sun has 13 known rings), researchers have been able to decipher not only the temperature, but also the bits that create the rings.

The scientists found that the densest, brightest ring — called the epsilon ring — is pretty darn cold (by human standards): 77 Kelvin, which is just 77 degrees above absolute zero and the equivalent of minus 320 degrees Fahrenheit (minus 196 degrees Celsius). For comparison, the lowest temperature on Earth — minus 135 F (minus 93 C) — was recorded on an ice ridge in Eastern Antarctica. [Photos: The 8 Coldest Places on Earth]

Study researcher Imke de Pater, of UC Berkeley, told Live Science that she and her co-authors can't determine the temperature of the inner rings with the data they have so far.

For the study, the scientists looked at the rings through the Very Large Telescope in Chile, which detects visible wavelengths — the icy components of the rings reflect a teensy bit of light in the optical range — and the Atacama Large Millimeter/submillimeter Array (ALMA), also in Chile, which zooms in on wavelengths that straddle the radio/infrared part of the electromagnetic spectrum.

The results were glowing, as the icy particles inside each ring emitted a smidge of heat in the form of infrared radiation, to create a light-up composite image. From those images, the astronomers found that the epsilon ring has a wonky makeup compared with other planetary rings.

"Saturn's mainly icy rings are broad, bright and have a range of particle sizes, from micron-sized dust in the innermost D ring, to tens of meters in size in the main rings," de Pater said in a statement. "The small end is missing in the main rings of Uranus; the brightest ring, epsilon, is composed of golf ball-sized and larger rocks."

In fact, Voyager 2 first spied this lack of itty-bitty particles when the craft photographed Uranus in 1986.

"It seems to me that the new images are confirming that big centimeter-sized objects (and larger) are likely the main constituent of the rings, which helps explain why they appear warmer than if it was lots of tiny dust particles," Leigh Fletcher, an astrophysicist at the University of Leicester, told Live Science in an email.

Indeed, the bone-chilling temperature of epsilon is a bit warmer than the researchers would have expected based on the amount of sunlight that hits objects at a Uranus distance.

"If these were tiny specks of dust, radiating away all the solar energy falling on them, then we'd expect them to be a few degrees cooler," Fletcher said. "But we can explain this warmth if we assume that the ring particles are slowly rotating and have a day-night contrast in temperature," with the side facing away from the sun being cooler until it rotates its face toward the sun again.

Fletcher added, "They're big enough that they don't have the same temperature everywhere, which means they're not re-radiating solar energy from their whole surface, and therefore can be a little warmer than expected."

The researchers said they hope that the new images will reveal more about not only the composition of the rings, but also whether or not they each came from different sources.

Planetary rings are made from the solar system's crumbs — whether from former asteroids getting sucked in by the planet's gravity, shards from moon collisions, or even the leftover scraps from the formation of the solar system 4.5 billion years ago.

• 11 Fascinating Facts About Our Milky Way Galaxy
• Spaced Out! 101 Astronomy Images That Will Blow Your Mind
• 15 Amazing Images of Stars

Originally published on Live Science.

Solar system marvels

Yellowstone National Park may have stunning vistas that impress mere Earthlings, but they’re nothing compared to strange and fascinating locations elsewhere in our solar system. Jupiter's Great Red Spot is a colossal storm larger than Earth. Venus' surface temperature is hot enough to melt lead. The largest mountain on any planet in our solar system, Mars' Olympus Mons, is three times higher than Mount Everest. And while any space geek worth her Europan sea salt might know about these splendors, the marvels of the solar system are almost endless. Here, we take a look at some of the less-well-known spots in our cosmic neighborhood that we’d most like to visit.

Mercury's ice traps

Up close to the blazing sun is not a place most people would think to look for frozen ice. But as the little planet Mercury spins next to its fiery parent star, a few craters at the poles are permanently hidden deep in shadow. With an ambient temperature of minus 280 degrees Fahrenheit (minus 173 degrees Celsius), these "deep-freeze traps" are the perfect place for water ice to accumulate over the eons. All together, these ice traps could hold more water than similar deposits on the moon, Sean Solomon, director of the department of terrestrial magnetism at the Carnegie Institution of Washington, previously told Live Science.

Venus: Abode of life?

Bone-dry and hellishly hot, Venus seems unlikely to contain an oasis. Yet 30 miles (48 kilometers) above its infernal surface, there exists a cloud layer with downright balmy conditions. Temperatures and pressures here are not all that different from those found on the Earth's surface. The ample sunshine and complex chemicals could provide power to photo- and chemosynthetic organisms. The only downside? There's a fair amount of sulfuric acid in the clouds. But then again, extremophile microbes on Earth have endured much harsher environments.

Comet-Asteroid Phaethon

The space rock Phaethon sports a rare blue color and an extremely eccentric orbit that takes it close to the sun and then past Mars. Such an orbit is typical of icy comets, but when Phaethon approaches our solar system's central star, it doesn't produce the beautiful tail-like coma characteristic of nearly all comets.Therefore, many astronomers consider it to be more like an asteroid. Theories abound about what exactly is going on with this odd object, including the possibility that it is a dormant comet, or a comet that turned into an asteroid over time.

Ida and Dactyl

In 1993, the Galileo spacecraft was en route to Jupiter. Along the way, it stopped to photograph an unusual object—the asteroid Ida, which became only the second asteroid ever to be visited by a probe. Ida contained a tiny surprise for scientists: an itty-bitty moon named Dactyl, the first satellite discovered orbiting around an asteroid. Both objects are a bit strange in that they experience space-weathering from the sun that causes their surfaces to turn red over time. Scientists are still scratching their heads over exactly how old Ida is and how it got this little moon.

Janus and Epimetheus

The ringed beauty Saturn is host to a wide variety of wonderful moons. And two of its potato-shaped satellites, Janus and Empimetheus, have in a unique arrangement. These special partners share an orbit wherein one is 31 miles (50 km) closer to Saturn than the other is. Once about every four years, the more distant moon catches up to the closer one, and the two perform a gravitational do-si-do, switching places. No other moons in the solar system are known to have such interchanging orbital mechanics.

Yin-Yang Iapetus

Saturn's third-largest moon, Iapetus, is a walnut-shaped wonder, with a bulging equator and a bizarre black-and-white surface. One hemisphere of the satellite is coal-black, while its other side is far brighter. A raised mountain range encircles its equator, containing some of the highest peaks in the solar system. So far, no one has been able to explain Iapetus' two-tone appearance; some astronomers suggest that the murkier side could have been created by particles originating from another of Saturn’s moons, Phoebe, or perhaps by the eruption of dark hydrocarbons from ice volcanoes. There have even been conspiracy-like whispers that Iapetus is not a natural satellite, but rather something built or modified by an alien civilization, though that possibility is well outside mainstream scientific thinking.

Miranda's Gnarly Cliffs

The ice giant Uranus' moon Miranda is a spelunkers dream — its jagged surface is replete with canyons, scarps, terraced outcrops, and a cliff whose floor is approximately 12.4 miles (20 km) down, the highest known cliff in the solar system. Miranda's geological scars could be due to flowing ice from the moon's interior that, at some point, were pushed up to the surface. An even wilder theory proposes that the moon was shattered several times and came back together, creating its extremely uneven features.

Triton and Proteus

Triton is the largest of blue Neptune's moons, and the only round one.This moon is high on the list of researchers' places to send a spacecraft, because it sports so many strange qualities. Triton is on a "retrograde" orbit, revolving in the opposite direction of the planet and other moons, suggesting it could have been a captured, Pluto-like body. From its surface rise bizarre ice volcanoes, making it one of the farthest bodies in the solar system known to have active geophysics. Triton's sibling, Neptune’s second largest moon, Proteus, is also pretty unusual. Rather than being round, this moon is shaped like what mathematicians call an irregular "polyhedron" (a solid object with many plane faces), and what "Dungeons and Dragons" nerds know as a 20-sided dice. Proteus' surface is pinkish-red, perhaps the result of complex organic compounds like hydrocarbons.

Ultima Thule

After speeding by distant Pluto, NASA's New Horizons mission made a brief encounter with an even more out-there body. Nicknamed Ultima Thule, the frozen Kuiper belt object at first looked like two spheres stuck together, forming a celestial snowman. But after the spacecraft completed its flyby, Ultima Thule was revealed to be as flat as a pancake, more like two skipping stones that had somehow gotten wedged to one another. Scientists are likely to ponder this strange state of affairs for a long time.

The Sun's Tail

At the edge of the solar system, where the sun's influence is nearly depleted, lives a large structure called the heliotail. The tail drags behind the bullet-shaped heliosphere, a bubble surrounding our solar system that was created by the sun's wind and magnetic field. The comet-like heliotail had never been seen until NASA's Interstellar Boundary Explorer (IBEX) photographed it in 2013, finding what looked unexpectedly like a four-leaf clover. This quadratic shape arises from the fast solar wind shooting out from near the sun's poles and slower wind flowing from near the sun's equator, researchers told Live Science's sister site, Space.com.

Uranus is arguably the most mysterious planet in the solar system – we know very little about it. So far, we have only visited the planet once, with the Voyager 2 spacecraft back in 1986. The most obvious odd thing about this ice giant is the fact that it is spinning on its side.

Unlike all the other planets, which spin roughly "upright" with their spin axes at close to right angles to their orbits around the sun, Uranus is tilted by almost a right angle. So in its summer, the north pole points almost directly towards the sun. And unlike Saturn, Jupiter and Neptune, which have horizontal sets of rings around them, Uranus has vertical rings and moons that orbit around its tilted equator.

The ice giant also has a surprisingly cold temperature and a messy and off-centre magnetic field, unlike the neat bar-magnet shape of most other planets like Earth or Jupiter. Scientists therefore suspect that Uranus was once similar to the other planets in the solar system but was suddenly flipped over. So what happened? Our new research, published in the Astrophysical Journal and presented at a meeting of the American Geophysical Union, offers a clue.

Cataclysmic collision

Our solar system used to be a much more violent place, with protoplanets (bodies developing to become planets) colliding in violent giant impacts that helped create the worlds we see today. Most researchers believe that Uranus' spin is the consequence of a dramatic collision. We set out to uncover how it could have happened.

We wanted to study giant impacts on Uranus to see exactly how such a collision could have affected the planet's evolution. Unfortunately, we can't (yet) build two planets in a lab and smash them together to see what really happens. Instead, we ran computer models simulating the events using a powerful supercomputer as the next best thing.

The basic idea was to model the colliding planets with millions of particles in the computer, each representing a lump of planetary material. We give the simulation the equations that describe how physics like gravity and material pressure work, so it can calculate how the particles evolve with time as they crash into each other. This way we can study even the fantastically complicated and messy results of a giant impact. Another benefit of using computer simulations is that we have full control. We can test a wide variety of different impact scenarios and explore the range of possible outcomes.

Our simulations (see above) show that a body at least twice as massive as the Earth could readily create the strange spin Uranus has today by slamming into and merging with a young planet. For more grazing collisions, the impacting body's material would probably end up spread out in a thin, hot shell near the edge of Uranus' ice layer, underneath the hydrogen and helium atmosphere.

This could inhibit the mixing of material inside Uranus, trapping the heat from its formation deep inside. Excitingly, this idea seems to fit with the observation that Uranus' exterior is so cold today. Thermal evolution is very complicated, but it is at least clear how a giant impact can reshape a planet both inside and out.

Super computations

The research is also exciting from a computational perspective. Much like the size of a telescope, the number of particles in a simulation limits what we can resolve and study. However, simply trying to use more particles to enable new discoveries is a serious computational challenge, meaning it takes a long time even on a powerful computer.

Our latest simulations use over 100m particles, about 100-1,000 times more than most other studies today use. As well as making for some stunning pictures and animations of how the giant impact happened, this opens up all sorts of new science questions we can now begin to tackle.

This improvement is thanks to SWIFT, a new simulation code we designed to take full advantage of contemporary "supercomputers". These are basically lots of normal computers linked up together. So, running a big simulation quickly relies on dividing up the calculations between all parts of the supercomputer.

SWIFT estimates how long each computing task in the simulation will take and tries to carefully share the work evenly for maximum efficiency. Just like a big new telescope, this jump to 1,000 times higher resolution reveals details we have never seen before.

Exoplanets and beyond

As well as learning more about the specific history of Uranus, another important motivation is understanding planet formation more generally. In recent years, we have discovered that the most common type of exoplanets (planets that orbit stars other than our sun) are quite similar to Uranus and Neptune. So everything we learn about the possible evolution of our own ice giants feeds in to our understanding of their far distant cousins and the evolution of potentially habitable worlds.

One exciting detail we studied that is very relevant to the question of extraterrestrial life is the fate of an atmosphere after a giant impact. Our high resolution simulations reveal that some of the atmosphere that survives the initial collision can still be removed by the subsequent violent bulging of the planet. The lack of an atmosphere makes a planet a lot less likely to host life. Then again, perhaps the massive energy input and added material might help create useful chemicals for life as well. Rocky material from the impacting body's core can also get mixed into the outer atmosphere. This means we can look for certain trace elements which might be indicators of similar impacts if we observe them in an exoplanet's atmosphere.

Lots of questions remain about Uranus, and giant impacts in general. Even though our simulations are getting more detailed, we still have lots to learn. Many people are therefore calling for a new mission to Uranus and Neptune to study their strange magnetic fields, their quirky families of moons and rings and even simply what precisely they're actually made of.

I would very much like to see that happen. The combination of observations, theoretical models and computer simulations will ultimately help us understand not only Uranus, but the myriad planets that fill our universe and how they came to be.

Jacob Kegerreis, PhD Student, Computational Astronomy, Durham University

This article is republished from The Conversation under a Creative Commons license. Read the original article. Follow all of the Expert Voices issues and debates — and become part of the discussion — on Facebook, Twitter and Google +. The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was originally published on Space.com.

Whoa, that's weird science

There's no question that science is full of explanations that defy our commonsense expectations. And every year, researchers find ever more mystifying discoveries about the universe we live in. From disgusting medical anomalies to blueberry planets to giant tadpoles, here are the 14 most bizarre findings of 2018.

Karate-kicking cockroaches avoid zombification

Parasitic wasps are among the most diverse of all animals, with nearly one species for every other known insect, according to research published this year in BMC Ecology. One particular fiend, known as the emerald jewel wasp, preys on cockroaches. After delivering a paralyzing sting to the victim's legs, the wasp then stings its brain and floods it with neurotoxins that hijack the cockroach's nervous system, turning the lowly crawler in a mind-controlled zombie. The cockroaches were once thought to have no defense against this gruesome attack, but new research shows that the prey can knock away their parasitic predator with a karate kick to the head that sends the wasps searching for an easier target.

A long-standing lump in the throat

Some people are born with a silver spoon in their mouth. Others swallow them on a dare. That was the case for a patient known only as "Mr. Zhang" who arrived at Xinjiang Meikuang General Hospital in China in October. The spoon — which was actually made of steel — had become lodged in the man's esophagus a year earlier and was apparently not causing him much suffering until he began having pains after being punched in the chest. (Mr. Zhang sounds like he lives an interesting life.) Three doctors removed the 8-inch (20 centimeters) object during a procedure that lasted 2 hours. "I was very surprised," Dr. Xiwu, the hospital's director of ear, nose and throat ailments, said in a statement. "I have never encountered a similar patient."

The hexagon, the dodecahedron, the...scutoid?

Triangles and squares are so passé. Geometry enthusiasts will be thrilled to learn that there's a new shape around, the scutoid. Looking like a strange, 3D crystal, the scutoid was named after a roughly triangle-shaped part of a beetle's thorax. The newly discovered form has actually been around in nature for a long time. Epithelial cells found on the surface of animals' bodies, are often packed together into scutoid-al shapes, which minimizes their energy usage and maximizes their stability.

What if Earth became blueberries?

It's not a question most people think about, but one computational neuroscientist wondered what would happen if the entire Earth were suddenly transformed into a bunch of blueberries. Anders Sandberg, who works at the University of Oxford's Future of Humanity Institute, wrote about this fanciful idea in a paper published to the preprint server arXiv (whose articles have not yet passed through peer review) in July . The first thing that would apparently happen is a drastic reduction in the force of gravity, since blueberries are less dense than the rocky substrate of our planet. The crushing force of the outer-edge blueberries would then compress and heat up the inner ones into a thick jam that would generate rollicking earthquakes. At blueberry Earth's center would be a hot core of blueberry "granita" ice, smushed into a solid by the extreme pressure. It can only be assumed that any intelligent beings evolving on such a planet would likely invent the pancake before the wheel.

A tadpole as long as your face

At first, they thought it was a fish. But once volunteers aiming to remove invasive bullfrogs (Lithobates catesbeianus) from Arizona looked closer, they realized they'd come across a monstrous pollywog. In a blog post, herpetologist Earyn McGee described the discovery, naming it Goliath, and speculating that the tadpole, which is much larger than the average bullfrog young, was suffering some kind of hormonal imbalance, as Live Science previously reported. Goliath is larger than a soda can, nearly as long as a banana, and definitely big enough to rest comfortably across a human face. Oh, yes, he's still alive and growing.

Dog licks man, man requires amputation

Dog owners tell themselves their pets would never do anything to intentionally harm them. Unfortunately, a Wisconsin man named Greg Manteufel learned the hard way that he probably shouldn't have let his best friend lick him too much. After being admitted to a hospital, Manteufel was found to be suffering from an infection by a bacteria called Capnocytophaga, which led to the amputation of his legs and parts of his arms. The bacteria live in most household pets without causing problems, but if they get passed to a human via a bite or scratch and spread through a person's bloodstream, they can cause deadly consequences. Dr. Silvia Munoz-Price, an infectious-disease specialist told Live Science that the case is extremely rare. "More than 99 percent of the people that have dogs will never have this issue. It's just chance," she said.

Ancient Chinese tomb contains extinct gibbon bones

In 2004, archaeologists excavated the tomb of Lady Xia, grandmother to the Chinese emperor Qin Shi Huang, who lived between 259 B.C. and 210 B.C. The burial site contained a number of objects and animal bones, which may have been the royal woman's pets. One of these skeletons turned out not to match that of any known species and, in July, researchers announced that they had discovered a previously unidentified gibbon that went extinct sometime since the last ice age, naming it Junzi imperialis. When it was alive, the ape probably weighed about 13 lbs. (6 kilograms) and ate a mix of fruits and leaves, as well as the occasional insect or bird's egg, Helen Chatterjee, a professor of biology at University College London, told Live Science

Eye lump is actually skin-crawling worm

Even horror movies aren't this gross. When a Russian woman found a small lump below her left eye, she didn't think it was particularly concerning. But after the lump began to move above her eye and then into her lip, she sought medical attention. Doctors removed a thread-like worm known as Dirofilaria repens, which naturally infects dogs, cats, foxes and other wild mammals . The worms spread through mosquito bites and typically live in the tissue under the skin. Humans, it turns out, are just accidental hosts that the worm had no intention of defiling. Small comfort to those who will now suffer nightmares about this incident.

Uranus smells like rotten eggs

The jokes practically wrote themselves in April after astronomers announced that Uranus' atmosphere was chock-full of hydrogen sulfide, a stinky gas that comes out of sewers on Earth. Researchers have long debated the seventh planet's atmospheric composition and new data from the Gemini North telescope, which sits on Mauna Kea in Hawaii, identified telltale signatures of the smelly substance in light from the planet. "If an unfortunate human were to ever descend through Uranus' clouds, they would be met with very unpleasant and odiferous conditions," study co-author Patrick Irwin, a professor of planetary physics at the University of Oxford, said in a statement at the time . He then added that "suffocation and exposure in the negative 200 degrees Celsius [minus 328 degrees Fahrenheit] atmosphere made of mostly hydrogen, helium and methane would take its toll long before the smell."

Orange snow falls over Eastern Europe

Those dreaming of something other than a white Christmas might want to check out the Russian city of Sochi. Back in May, visitors began posting photos to Instagram of otherworldly orange snow on the mountains. Meteorologists attributed the phenomenon to sand and dust that had been kicked up by storms in Africa. The deep-tinged snow also fell over parts of Bulgaria, Ukraine, Romania, Moldova and Greece. The Athens Observatory was quoted by CNN as saying that it was "one of the largest transfers of desert sand to Greece from the Sahara ever."

Toad found with no face

In the forests of Connecticut, herpetologist Jill Fleming spotted an unusual sight. An American toad (Anaxyrus americanus) appeared to be lacking its entire face and "kept hopping into things," she tweeted. The finding, which occurred two years ago, still has no full explanation and so Fleming turned to the social media site to see if the collective scientific hive-mind might come up with ideas. The most likely explanation seemed to be that the unfortunate toad had gone into hibernation and been attacked by a flesh-eating toad fly larvae, which ate its face, but left the rest of its body well enough to jump around.

Suppressed sneeze causes ruptured throat

Let this be a warning: Do not stifle a sneeze! After a 34-year-old man in England tried holding his nose and shutting his mouth to prevent someone having to tell him 'Gesundheit,' he felt a terrible popping sensation in his neck. Doctors found an array of air bubbles trapped under his skin, mostly in his neck region, determining that the suppressed sneeze had torn a hole in the bottom part of his pharynx, or throat. The man survived and eventually healed. Two months later, he had no further health problems. But the harrowing incident led researchers to understatedly report in January that "halting a sneeze via blocking nostrils and mouth is a dangerous maneuver and should be avoided."

Australian birds steal fire

Repeating the Greek legend of Prometheus, who stole fire from the gods to give to humankind, several Australian birds seem to have learned that snatching bits of smoldering grasses or branches from naturally occurring forest fires lets them light new blazes. Researchers Down Under collected Aboriginal accounts of birds known as firehawks — black kites (Milvus migrans), whistling kites (Haliastur sphenurus) and brown falcons (Falco berigora) — performing this blazing behavior, sometimes alone or in coordination with other firehawks. They believe the birds are using the new infernos to drive small prey from grassy areas into exposed areas, making the creatures easier to hunt.

Heat wave boils bats

The terrible effects of climate change are worsening every year. In January, a heat wave in the Australian state of New South Wales saw temperatures skyrocketing to 111.5 degrees Fahrenheit (44.2 degrees Celsius), causing at least 200 bats to fall from the sky, dead. The heat-stricken creatures basically boiled alive, said Kate Ryan, who manages the colony of gray-headed flying foxes (Pteropus poliocephalus). "It affects their brain — their brain just fries and they become incoherent," she said, according to a local newspaper.

Originally published on Live Science.

Uranus smells like rotten eggs, and that is not a joke. A new study finds that the seventh planet from the sun has an upper atmosphere flush with hydrogen sulfide.

Hydrogen sulfide is a gas best known for its repulsive smell; the gas emanates from sewers and volcanoes on Earth, explaining why some hot springs, which are fed by geothermally heated water, smell like breakfast gone bad. Astronomers have now discovered that the gas is common in the cloud tops of Uranus.

That hydrogen sulfide composition is different than what is found in the upper atmospheres of Uranus' fellow giant planets Jupiter and Saturn, where ammonia dominates, said Leigh Fletcher, a study co-author and senior research fellow in planetary science at the University of Leicester in England. Ammonia is made of nitrogen bonded with hydrogen, while hydrogen sulfide is hydrogen bonded with sulfur. [7 Everyday Things That Happen Strangely in Space]

"During our solar system's formation, the balance between nitrogen and sulfur (and hence, ammonia and Uranus' newly detected hydrogen sulfide) was determined by the temperature and the location of the planet's formation," Fletcher said in a statement.

Faint signals

Scientists have long debated the precise composition of Uranus' upper atmosphere, simply because they lacked instruments sensitive enough to detect the gases found there. For the new study, the team used the Gemini North telescope, a 26.5-foot (8.1 meters) telescope that sits on the Mauna Kea volcano in Hawaii. Researchers used the telescope's Near-Infrared Integral Field Spectrometer (NFIS), first designed to image the outsides of black holes in far-off galaxies, to sample reflected sunlight from Uranus' high atmosphere.

Thanks to that instrument's enormous sensitivity, researchers were able to detect very faint lines on the light spectrum indicating that hydrogen sulfide had absorbed some wavelengths from the sunlight, the scientists said.   

"Only a tiny amount [of hydrogen sulfide] remains above the clouds as a saturated vapor," Fletcher said, and this made detection a challenge.

Nasty atmosphere

The findings will help clarify how Uranus and its neighboring ice giant, Neptune, formed, the researchers said. They reported their results April 23 in the journal Nature Astronomy. There is likely a more-concentrated reservoir of hydrogen sulfide beneath the cloud deck, the researchers said, but this likely lies beyond Earth-bound telescopes' detection abilities.

However, the clouds on Uranus definitely contain chemicals that a human could detect in person, the researchers said.

"If an unfortunate human were to ever descend through Uranus' clouds, they would be met with very unpleasant and odiferous conditions," study co-author Patrick Irwin, a professor of planetary physics at the University of Oxford, said in the statement. That is, they would if that person miraculously lived to take a whiff.

"Suffocation and exposure in the negative 200 degrees Celsius [minus 328 degrees Fahrenheit] atmosphere made of mostly hydrogen, helium and methane would take its toll long before the smell," Irwin added. 

Originally published on Live Science.

It's both solid and liquid, it's 60 times denser than ordinary water ice, and it forms at temperatures almost as hot as the sun's surface.

It's superionic ice — and for the first time, scientists have made it in the lab.

This high-pressure form of water ice has long been thought to exist in the interiors of Uranus and Neptune. But until now, its existence was only theoretical.

"Our work provides experimental evidence for superionic ice and shows that these predictions were not due to artifacts in the simulations, but actually captured the extraordinary behavior of water at those conditions," Marius Millot, a physicist at Lawrence Livermore National Laboratory in California, said in a statement from the laboratory. Millot was the leader author of a new study describing the work.

Scientists first predicted the existence of a weird water phase that makes the substance both solid and liquid at the same time 30 years ago. It's also way denser than ordinary water ice because it forms only under extreme heat and pressure, such as those found inside giant planets. During the superionic phase, the hydrogen and oxygen within water molecules behave bizarrely; hydrogen ions move like a liquid, inside of a solid crystal lattice of oxygen. [The Surprisingly Strange Physics of Water]

Making the ice was complicated. First, the team compressed water into an ultrastrong cubic crystalline ice, in a different crystal form than what you see in ordinary ice cubes. To do that, the researchers used diamond anvil cells to apply 360,000 pounds per square inch (2.5 gigapascals (GPa) of pressure; that's about 25,000 times the atmospheric pressure on Earth). Next, the researchers heated and compressed the cells even further, using laser-driven shocks. Each crystal ice structure received up to six laser beams of more than 100 times that high pressure.

"Because we pre-compressed the water, there is less shock-heating than if we shock-compressed ambient liquid water," Millot said. The new method lets researchers "access much colder states at high pressure than in previous shock-compression studies."

Once the superionic ice was ready, the team moved quickly to analyze its optical and thermodynamic properties. They had only 10 to 20 nanoseconds to perform the work, before pressure waves released the compression, and the water dissolved. And the results were bizarre. They found that the ice melts at an extraordinary 8,540 degrees Fahrenheit (4,725 degrees Celsius ) at 29 million pounds per square inch (200 GPa) of pressure. That pressure is about 2 million times the atmospheric pressure on Earth.

"It's … mind-boggling that frozen water ice is present at thousands of degrees inside these planets, but that's what the experiments show," Raymond Jeanloz, a co-author of the study and planetary physicist at the University of California, Berkeley, said in the same statement.

The new findings could provide a peek inside the interiors of planets such as Uranus and Neptune. Planetary scientists suggest these worlds' innards are composed of up to 65 percent water by mass, plus some ammonia and methane.

Previous work suggested these planets would have "fully fluid" heat-transferring interiors, but the addition of superionic ice changes the picture. The new research instead proposes "a relatively thin layer of fluid and a large 'mantle' of superionic ice," the researchers said in the statement.

That picture of the mini-giant planets' interiors would confirm a computer simulation performed a decade ago that tried to explain the weird magnetic fields at Uranus and Neptune. Uranus' magnetic field is tilted 59 degrees away from the planet's axis. Neptune's magnetic poles have a roughly 47-degree tilt. This is extreme compared with Earth, which has only an 11-degree tilt. Their magnetic fields also may behave differently; for example, Uranus' field may turn on and off like a strobe.

More detailed study of these planets will have to wait until a spacecraft is available. Fortunately, NASA is proposing a Uranus and/or Neptune spacecraft that would zoom out to these planets sometime in the next few decades. Meanwhile, the experimenters plan to push their compression further to simulate conditions inside of even larger giant planets, such as Jupiter or Saturn.

A study based on the research was published in February in the journal Nature Physics.

Original article on Live Science.