​​We tend to think of metals as hard, strong and resistant to high temperatures — just look at iron, aluminum and steel. While this is generally true, there's one key exception: mercury. With a melting point of minus 37.9 degrees Fahrenheit (minus 38.8 degrees Celsius), mercury is one of only two elements that are liquid at room temperature. (The other is bromine, which is not a metal.)

But why is mercury so different from its fellow metals?

The answer comes down to mercury's position in the periodic table and its knock-on effect on how the metal bonds together.

Melting point is directly correlated with bond strength — "the stronger the bonds, the more energy, in the form of heat, is required to break them," Zoe Ashbridge, a senior lecturer in chemistry for the U.K. Ministry of Defence, told Live Science.

Atoms of mercury, like atoms of all other metals, bind together through metallic bonding — a lattice of positively charged metal particles known as ions, is surrounded by a sea of delocalized (freed) electrons, and electrostatic attraction between these oppositely charged particles acts as the glue that holds the metal together. This structure explains many of the other signature properties of metals, such as electrical conductivity, as the electrons can move freely through the material, and mouldability, as the layers of positive particles can slide over one another to adopt a new shape, lubricated by the free electrons. But it is specifically the strength of the electrostatic attraction that governs the melting point.

The availability of outer electrons to create this delocalized sea is therefore a key factor. "The more positive the metal center is and the more delocalized valence electrons on the outside, the greater the attraction is, and generally this tracks from left to right in the periodic table," Ashbridge explained.

As a group 12 metal, mercury theoretically has 12 outer electrons it could contribute to metallic bonding. "However, all of those electrons are in "filled subshells," she added. "When they are full, that makes them more stable and less likely to delocalize, and this makes mercury particularly reluctant to share its electrons, even with other mercury atoms."

Yet this filled-subshell effect isn't big enough to explain mercury's unusually low melting point. The strength of metallic bonding — and, therefore, the melting point — also decreases from the top to the bottom of the periodic table, as the atoms get larger. But extrapolating from these established trends, mercury should still have a melting point of around 266 F (130 C), which would make it solid at room temperature.

So what causes this giant disparity?

Mercury's liquid state results almost entirely from relativistic effects, said Peter Schwerdtfeger, a quantum physicist at Massey University in New Zealand. Toward the bottom of the periodic table, the electrons in the heaviest elements experience such strong attraction to the atomic nucleus that they move close to the speed of light. At this point, they no longer obey the laws of classical physics, and the resulting quantum phenomena — known as relativistic effects — lead to surprising physical properties. How these manifest depends on the element.

"Relativistic effects become extremely important for the group 11 and group 12 elements, where gold and mercury are," he told Live Science. Consequently, the weird physical properties arising from these quantum effects are most observable in these elements. Gold has an extremely unusual yellowish hue and mercury is a liquid at room temperature.

"They show us a so-called maximum of relativistic effects, and the outer shell of these atoms contract as a result. It's enormous. For mercury, it's about 20%," Schwerdtfeger said. In chemistry terms, this relativity-induced contraction is most easily explained by once again considering mercury's electron configuration.

The full 4f subshell, which contains the electrons associated with the rare earth, or lanthanide elements, is extremely poor at shielding the other electrons from the nuclear charge. This means the outermost electrons are held much closer to the nucleus than usual — a phenomenon called lanthanide contraction. These contracted electrons move close to the speed of light and therefore experience relativistic effects.

"This increases their mass, and when they have an increased mass due to this high speed, it pulls those electrons even closer to the nucleus," Ashbridge said. Consequently, the relativistic effects reduce the availability of the electrons to contribute to metallic bonding, thus lowering the melting point of the metal below room temperature.

At a quantum mechanical level, though, this qualitative explanation is extremely challenging to back up with calculations.

"The Schrödinger equation" — which usually describes the possible positions of particles such as electrons — "doesn't fulfill the relativity principle of Albert Einstein," Schwerdtfeger explained. As a result, this equation doesn't work for high-speed particles such as the electrons in mercury. Scientists must instead turn to the significantly more complicated Dirac equation, making any simulations extremely computationally demanding.

Eventually, though, advances in computing enabled Schwerdtfeger to devise a model that could accurately simulate mercury melting and provide a quantum theoretical explanation for the anomalous melting point.

"Using what we call density functional theory, we were able to establish that the melting point is lowered by over 200 degrees Celsius [360 F] by the relativistic effects," he said. These quantum contributions dominate, so while periodic trends predict a low melting point for mercury, the relativistic effects make the element a liquid at room temperature.

Periodic table of elements quiz: How many elements can you name in 10 minutes?

Venus, Jupiter and Saturn are easy to see in the night sky, but few skywatchers have ticked Mercury off their planetary bucket list. That may change on Tuesday, Nov. 25, when early risers (or late sleepers) will get a rare chance to see the closest planet to the sun together with its bright neighbor, Venus.

Mercury is notoriously difficult to spot due to its close orbit, which often causes the small planet to be lost in the sun's glare. However, Mercury occasionally makes a brief appearance before sunrise.

A particularly good window for Mercury watching opens on Nov. 25 and continues until around Dec. 25. It begins with a close conjunction, when Mercury will appear just above the brighter Venus in the east-southeast sky. You'll need a clear view of the southeast horizon to see the duo rise together and a pair of good binoculars to see the planets clearly (though be sure to put the binoculars away before sunrise where you are). Mercury appears in binoculars as a faint, steady light.

During the conjunction, Mercury will shine at magnitude -2 and Venus will be at magnitude -3.8, making the "Swift Planet" about five times dimmer than the "Morning Star." (In astronomy, lower magnitudes indicate brighter objects.)

Mercury is visible from Earth only occasionally because of the tiny planet's short, swift orbit; it takes just 88 days to complete one lap of the sun. That's why Mercury almost always appears to be lost in the sun's glare. However, when it moves to the western side of the sun as seen from Earth, it appears in the predawn sky, rising shortly before the sun. This brief morning apparition will occur around Mercury's greatest western elongation on Dec. 7, which will be when it's farthest from the sun from Earth's point of view and thus highest in the predawn sky.

This conjunction has a bigger significance, because as Mercury rises, Venus sinks. Having been bright in evening skies in early 2025, Venus is approaching the end of its bright morning apparition. It's rising later each morning and will soon fade from view as it retreats into the sun's glare.

On Jan. 6, 2026, Venus will pass between Earth and the sun — what astronomers call superior conjunction.In the weeks after, Venus will reemerge in the evening sky and reach peak brightness on Sept. 22, 2026, according to EarthSky.

Editor's note: This story was updated on Nov. 24 to indicate the conjunction is happening overnight tonight.

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.

Most meteorites that have reached Earth come from the asteroid belt between Mars and Jupiter. But we have 1,000 or so meteorites that come from the Moon and Mars. This is probably a result of asteroids hitting their surfaces and ejecting material towards our planet.

It should also be physically possible for such debris to reach the Earth from Mercury, another nearby rocky body. But so far, none have been confirmed to come from there — presenting a longstanding mystery.

A new study my colleagues and I conducted has discovered two meteorites that could have a Mercurian origin. If confirmed, they would offer a rare window into Mercury's formation and evolution, potentially reshaping our understanding of the planet nearest the Sun.

Because Mercury is so close to the Sun, any space mission to retrieve a sample from there would be complex and costly. A naturally delivered fragment, therefore, may be the only practical way to study its surface directly — making such a discovery scientifically invaluable.

Observations from NASA's Messenger mission have inferred the surface composition of Mercury. This suggests the presence of minerals known as such as sodium-rich plagioclase (such as albite), iron-poor pyroxene (for example enstatite), iron-poor olivine (such as forsterite) and sulfide minerals such as oldhamite.

The meteorite Northwest Africa (NWA) 7325 was initially proposed as a possible fragment of Mercury. However, its mineralogy includes chromium-rich pyroxene containing approximately 1% iron. This poorly matches Mercury's estimated surface composition. As a result of this, and other factors, this link has been challenged.

Related: Mercury may have a 'potentially habitable' region below its surface, salty glaciers suggest

Aubrite meteorites have also been proposed as potential Mercurian fragments. Recent modeling of their formation suggests an origin from a large planetary body approximately 5,000km in diameter (similar to Mercury), potentially supporting this hypothesis.

Although aubrites do not exhibit chemical or spectral (the study of how light is broken up by wavelength) similarities with Mercury's surface, it has been hypothesized that they may derive from the planet's shallow mantle (the layer beneath the surface). Despite ongoing research, the existence of a definitive meteorite from Mercury remains unproven.

Our latest study investigated the properties of two unusual meteorites, Ksar Ghilane 022 and Northwest Africa 15915. We found that the two samples appear to be related, probably originating from the same parent body. Their mineralogy and surface composition also exhibit intriguing similarities to Mercury's crust. So this has prompted us to speculate about a possible Mercurian origin.

Both meteorites contain olivine and pyroxene, minor albitic plagioclase and oldhamite. Such features are consistent with predictions for Mercury's surface composition. Additionally, their oxygen compositions match those of aubrites. These shared characteristics make the samples compelling candidates for being Mercurian material.

However, notable differences exist. Both meteorites contain only trace amounts of plagioclase, in contrast to Mercury's surface, which is estimated to contain over 37%. Furthermore, our study suggests that the age of the samples is about 4,528 million years old. This is significantly older than Mercury's oldest recognised surface units, which are predicted (based on crater counting) to be approximately 4,000 million years.

If these meteorites do originate from Mercury, they may represent early material that is no longer preserved in the planet's current surface geology.

Will we ever know?

To link any meteorite to a specific asteroid type, moon or planet is extremely challenging. For example, laboratory analysis of Apollo samples allowed meteorites found in desert collection expeditions to be matched with the lunar materials. Martian meteorites have been identified through similarities between the composition of gases trapped in the meteorites with measurements of the martian atmosphere by spacecraft.

Until we visit Mercury and bring back material, it will be extremely difficult to assess a meteorite-planet link.

The BepiColombo space mission, by the European and Japanese space agencies, is now in orbit around Mercury and is about to send back high-resolution data. This may help us determine the ultimate origin body for Ksar Ghilane 022 and Northwest Africa 15915.

If meteorites from Mercury were discovered, they could help resolve a variety of long-standing scientific questions. For example, they could reveal the age and evolution of Mercury's crust, its mineralogical and geochemical composition and the nature of its gases.

The origin of these samples is likely to remain a subject of continuing debate within the scientific community. Several presentations have already been scheduled for the upcoming Meteoritical Society Meeting 2025 in Australia. We look forward to future discussions that will further explore and refine our understanding of their potential origin.

For now, all we can do is make educated guesses. What do you think?

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

Two rare twilight pairings will grace the June 2025 sky as the moon first passes close to elusive Mercury and then gets stunningly close to Mars.

Mercury is typically difficult to see and the conjunction between Mars and the moon will be particularly close, so both will be special sights for skywatchers.

The moon and Mercury meet-up comes as the "Swift Planet," which orbits the sun every 88 days, emerges from our star's glare into the post-sunset sky between June 21 and 30. According to NASA, Mercury will be visible just above the western horizon for 30 to 45 minutes after sunset.

On Thursday (June 26), a very slim crescent moon will appear between Mercury and the two bright stars in the constellation Gemini — Pollux and Castor — causing a brief line of lights in the post-sunset night sky. On Friday (June 27), the crescent moon will be higher in the sky, just above Mercury.

Precisely how low Mercury is, and how long it's observable during this period, depends on your location, so check Timeanddate.com or Stellarium.

That also applies to seeing what is arguably the skywatching highlight of the month on Sunday (June 29), when amateur astronomers will get a stunning view of a 24%-illuminated crescent moon directly beneath Mars in the constellation Leo, with just 0.2 degrees (12 arcminutes) separating them. The two worlds will appear so close that a fingertip held at arm's length will cover them.

The sight will be high in the western sky and easily visible without any equipment, but the two celestial bodies will be so close that they'll fit into the same field of view of a telescope. Although it's rare to see the moon and Mercury together in the night sky, and the closeness of the moon and Mars is also unusual, conjunctions between our natural satellite and planets are not uncommon. Planets orbit the sun on more or less the same plane, called the ecliptic. It's the same path the sun takes through the daytime sky as seen from Earth. The moon's orbit of Earth isn't quite the same, but its rather wobbly path differs from the ecliptic by only five degrees. Twice a month, the moon crosses the ecliptic (hence the name, because that sometimes causes solar and lunar eclipses), so it can come particularly close to a planet as seen from our terrestrial viewpoint.

The next significant close planetary conjunction will be the meeting of Venus and Jupiter in the pre-dawn hours of Aug. 12, when the two brightest planets will form a dazzlingly close pair.

Originally published on Live Science.

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?

Scientists have discovered a planet that is literally falling apart as it orbits its star. Located about 140 light-years from Earth in the Pegasus constellation , this doomed world named BD+05 4868 Ab whips around its star once every 30.5 hours — so close that its surface is being scorched into magma and vaporizing into space.

With each orbit, BD+05 4868 Ab leaves a blazing trail of molten rock behind it like a comet made of lava, offering a rare glimpse of an exoplanet in the final stages of its destruction. What's even more astonishing: with every blistering 30-hour orbit — which heats the planet to close to 3,000 degrees Fahrenheit (1,600 degrees Celsius) — the planet sheds as much mass of molten rock as an entire Mount Everest.

"The extent of the tail is gargantuan, stretching up to 9 million kilometers long, or roughly half of the planet's entire orbit," said Marc Hon, a postdoc in MIT's Kavli Institute for Astrophysics and Space Research in a statement.

This is an epic disintegration unfolding in real time, and the team predicts that it might take 1 to 2 million years for the entire planet to fully disintegrate. "We got lucky with catching it exactly when it's really going away," said Avi Shporer, a collaborator on the discovery who is also at the TESS Science Office. "It's like on its last breath."

Only three other disintegrating worlds have been identified among the more than 6,000 discovered exoplanets — each leaving a distinctive, comet-like tail of debris behind it. But BD+05 4868 Ab stands out: its tail is the longest of them all.

"That implies that its evaporation is the most catastrophic, and it will disappear much faster than the other planets," Hon said.

Because BD+05 4868 Ab orbits so perilously close to its star, its transit — the dip in starlight created as the planet passes in front of its star — appears especially bright and distinct. The planet was discovered with NASA's Transiting Exoplanet Survey Satellite (TESS) observatory. TESS, which scans nearby stars for periodic dips in brightness, revealed a strange, fluctuating transit that stood out from the usual planetary candidates.

This makes it an ideal target for NASA's James Webb Space Telescope, whose sensitive instruments can capture subtle changes in starlight to identify the chemical makeup of the vaporized rock trailing behind the planet. The result is a rare opportunity to watch a planet disintegrate in real time, and to study the composition of a world being stripped down to its core.

Hon says the discovery was a lucky break. "We weren't looking for this kind of planet," he explained. "We were doing the typical planet vetting, and I happened to spot this signal that appeared very unusual."

Though BD+05 4868 Ab's transit appears every 30.5 hours, the star's brightness took much longer than in other instances to return to normal. Even more bizarre was the depth the starlight's dip changed with every transit.

"The shape of the transit is typical of a comet with a long tail," Hon explained. "Except that it's unlikely that this tail contains volatile gases and ice as expected from a real comet — these would not survive long at such close proximity to the host star. Mineral grains evaporated from the planetary surface, however, can linger long enough to present such a distinctive tail."

Shporer explains that the planet is likely falling apart due to its low mass. "This is a very tiny object [between the size of Mercury and the moon], with very weak gravity, so it easily loses a lot of mass, which then further weakens its gravity, so it loses even more mass," Shporer stated. "It's a runaway process, and it's only getting worse and worse for the planet."

The team plans to carry out follow up observations this summer using the JWST. "This will be a unique opportunity to directly measure the interior composition of a rocky planet, which may tell us a lot about the diversity and potential habitability of terrestrial planets outside our solar system," Hon said.

And in the meantime, the researchers said they're looking for more examples in TESS data. "Sometimes with the food comes the appetite, and we are now trying to initiate the search for exactly these kinds of objects," Shporer said. "These are weird objects, and the shape of the signal changes over time, which is something that's difficult for us to find. But it's something we're actively working on."

Originally posted on Space.com.

Mercury's mysterious makeup may be the result of a grazing "hit and run" collision between two similar-sized protoplanets in the early solar system, a new study suggests.

Mercury, the smallest and innermost planet in our solar system, has a number of unusual characteristics that have long puzzled scientists. Despite being only slightly larger than Earth's moon, Mercury is extraordinarily dense. It boasts a disproportionately large, iron-rich core that makes up about 60% of its mass — twice that of other rocky planets such as Earth, Venus or Mars — challenging commonly accepted theories of planetary formation.

Adding to the mystery, data from NASA's MESSENGER probe, which orbited Mercury between 2011 and 2015, revealed that the planet's surface is surprisingly rich in volatile elements, including potassium, sulfur and sodium. These elements should have been stripped away had the planet endured a rare, single, massive impact in its youth, as researchers previously theorized.

One possible explanation is that young Mercury violently collided with a much larger protoplanet. However, simulations tracing terrestrial planet formation indicate that collisions among protoplanets of very different sizes and masses are rare, prompting scientists to seek alternate explanations of how Mercury could have lost so much outer material while preserving these volatiles.

The new simulations suggest that Mercury's anomalous makeup may stem from a more frequent cosmic event: a grazing collision with a protoplanet of comparable size.

"This kind of apparently 'lucky shot' would not have been unusual — and it might be exactly what created Mercury," study lead author Patrick Franco, a postdoctoral researcher in astrophysics at the Paris Institute of Planetary Physics, told Live Science.

"Our work reinforces the idea that giant impacts are not just a part of planet formation — they may actually be the primary drivers shaping the final structure of planets in the solar system," Franco said. The findings also raise questions about whether similar collisions could have shaped other planets, he added.

The researchers reported their findings March 4 in a paper posted to the preprint server arXiv, which is yet to be peer-reviewed.

"The timing of the impact is crucial"

The new simulations by Franco and his team successfully recreated Mercury's current internal structure and chemical makeup through collisions between similarly sized protoplanets. Notably, the team found that the angle at which the collision occurred determined the amount of mass lost by the proto-Mercury, with certain "glancing" impact angles resulting in the young world losing just the right amount of mass needed to match its present-day composition.

"What surprised us, at the end, was how effective this type of impact could be in explaining Mercury's unusual structure without needing to consider multiple collisions or extremely rare conditions," Franco said.

The researchers found that the collision would have needed to occur relatively late in the planet-formation process, some tens of millions of years after the solar system's birth, by which time young planets would have already developed distinct cores and mantles.

Mercury's collision with a fellow protoplanet around this time "can selectively strip away a lot of the outer rocky layer without melting everything or mixing the planet too much," Franco said.

An earlier impact, when more debris remained in the protoplanetary disk, could have resulted in further disruptive collisions, potentially leading to Mercury's accretion into a larger body, Franco said. "The timing of the impact is crucial."

The particular region of our solar system where the impact occurred also played a key role, the simulations showed. The region between Venus' and Earth's orbits during the early solar system was a chaotic and crowded zone, where rocky bodies frequently collided.

A "hit and run" impact between similarly sized protoplanets, like that proposed in the new study, was far more likely to occur in this crowded inner region rather than at Mercury's current orbit, the study found.

"This suggests that Mercury may have formed a bit farther out and then moved inwards later, avoiding being incorporated into the body with which it collided," Franco said.

However, the BepiColombo mission — a joint mission of the Japan Aerospace Exploration Agency (JAXA) and the European Space Agency (ESA) — is currently en route to Mercury, with its arrival anticipated in November 2026. This mission's data could soon challenge existing theories and spark further discussion of Mercury's formation and long-term evolution, scientists say.

"The debate over its origins is far from being settled," Franco said.

In a first-of-its-kind discovery, archaeologists in China have unearthed the 2,200-year-old burial of a woman whose teeth had been painted with cinnabar, a toxic red substance.

Cinnabar is a bright-red mineral that's made of mercury and sulfur. Although it's been used since at least the ninth millennium B.C. in religious ceremonies, art, body paint and writing, this is the first time it's been found on human teeth, according to a study published Feb. 24 in the journal Archaeological and Anthropological Sciences.

"This is the first and only known case of cinnabar being used to stain teeth in antiquity and throughout the world," study senior author Qian Wang, a professor of biomedical sciences at the Texas A&M University College of Dentistry, told Live Science in an email.

Archaeologists found the unusual remains while excavating a cemetery in Turpan City, in the Xinjiang region of northwestern China. Based on the cultural objects found in various graves, the archaeologists concluded that the deceased were Gushi people, who followed the Subeixi culture. The Subeixi culture, a horse riding pastoralist culture in which women rode horses using saddles, flourished in the Turpan basin nearly 3,000 years ago.

The cemetery lay on the main route of the Silk Road. The site was dated to 2,200 to 2,050 years ago via radiocarbon dating, putting it in the time frame when the Silk Road was active with the trade of precious goods, including cinnabar.

Related: Earliest evidence of mercury poisoning in humans found in 5,000-year-old bones

One of the graves in the cemetery held the remains of four individuals, including a juvenile. However, one adult skeleton in the burial stood out because its teeth had traces of red pigment. An anatomical analysis revealed that this individual was female and had died between the ages of 20 and 25. Intrigued, researchers scraped off a sample of the red pigment and studied it with three different spectroscopy methods, which can reveal the makeup of chemicals in a sample.

The analysis revealed that the pigment was cinnabar, which had been mixed with an animal protein, perhaps egg yolk or egg white, so it could be painted on the woman's teeth.

The team nicknamed the woman the "Red Princess of the Silk Road" after the "Red Queen," a female Maya aristocrat from seventh-century Mexico whose corpse was found covered in cinnabar powder inside a limestone sarcophagus.

Red Princess of the Silk Road

The Red Princess's teeth are an anomaly, as the Xinjiang region is not a source of cinnabar. However, it was mined and traded along the Silk Road in antiquity, the researchers noted. China and Europe, the beginning and end of the Silk Road, were the two most significant cinnabar-producing areas along this trade route. So it's possible that the cinnabar from the Turpan cemetery came from Europe, West Asia or other areas within China, such as the southwest, which was historically mined for cinnabar.

Although it's unknown why the woman's teeth were painted red, Wang said it could be "related to cosmetic enhancements, social status, or shamanism, or some kind of combination." Other mummies with facial paintings and tattoos have been found in the region and even the newly excavated cemetery, he noted. So it's possible that the Red Princess had facial painting or tattoos, distinct hairstyles, head dressing and costumes to go with her red teeth, Wang said.

Study co-author Li Sun, a professor of geology at Collin College in Texas, emphasized the dangerous nature of cinnabar application. She pointed out that during the whole process, from the preparation of the red pigment to its application (probably multiple times) inside the mouth, the red-toothed woman and her helpers might have inhaled fine particles of cinnabar or mercury vapors. Inhaling these substances is associated with harmful neurological effects such as headaches, insomnia, tremors, and cognitive and motor dysfunction, according to the World Health Organization.

Surprisingly, Wang and his team didn't find any evidence of mercury poisoning in her bones even though there's circumstantial evidence that it was applied repeatedly during her lifetime. "No traces of mercury were detected in her mandible, ribs and femur," Wang said. "Perhaps it was not [on her teeth] long enough to allow the toxin to be concentrated to a detectable level."

The rare planetary parade that brought all seven of Earth's neighboring worlds into the night sky is finally breaking up — but not before a final curtain call from the two planets closest to the sun. If you can find a view low to the western horizon on Monday, March 10, you may see a rare conjunction between Venus and Mercury — the two planets interior to Earth in the solar system — before they fully disappear in the sun's glare over the following nights.

Although Venus and Mercury will be visible only briefly after sunset, the sight of these two planets close to each other is quite rare. When two objects appear close to each other in the sky, it's called a conjunction. This one will take place over several nights, but the best time to see it will be on March 10, when Venus and Mercury will be visible about half an hour after sunset and remain in view for around 45 minutes.

The event will be visible to the naked eye, though a pair of stargazing binoculars may be helpful. Arguably more important are an unobstructed view due west and clear skies, as the conjunction will take place very close to the horizon.

Related: The 10 best stargazing events of 2025

The conjunction between the two inner planets is happening because of celestial mechanics. Venus, on its 225-day orbit of the sun, is currently lapping Earth on the inside track and is at its closest to Earth this month as it ever gets. The planet, which is now a crescent as seen from Earth in a telescope, will pass in front of the sun from Earth's point of view on March 22. It will remain lost in the sun's glare for some weeks, only to emerge into the predawn morning sky in April.

Mercury, which orbits the sun every 88 days, reaches its highest altitude in the evening sky on March 8. Although Mercury has been rising as Venus sinks, both will now disappear from the evening sky.

As Venus and Mercury exit the stage, a few remnants of the "planetary parade" will be visible after sunset. With Saturn already lost in the sun from Earth's point of view as it moves behind the sun on March 12, the only planets that will remain visible to the naked eye in the night sky will be Mars and Jupiter.

As we bid farewell to the planetary parade, you can still look forward to a total lunar eclipse that will be visible from North America overnight from March 13 to 14. Here are the places that will get the best views.

A stunning photo has captured all seven of our neighboring planets in Earth's sky at the same time, possibly for the first time ever.

The composite image, captured by astrophotographer Josh Dury, shows Mars, Jupiter, Uranus, Saturn, Venus, Neptune and Mercury in alignment thanks to a rare "planetary parade" taking place this weekend for the first time since 1982. (Here's how you can see it for yourself tonight).

While spacecraft, such as NASA's Voyager 1, have snapped all the planets in the sky from space, terrestrial cameras have only recently become advanced enough to capture them from the ground — meaning Dury's photo is likely the very first of its kind.

"Seven (arguably, 8) is a feat that to my prior knowledge has not been achieved before," Dury told Live Science in an email — suggesting that if we include Earth itself, visible in the foreground, the image's planet total comes to eight. "This image could hold a record for being the first of its kind to photograph all the planets of the solar system, blended into a stitched panoramic image."

Dury captured the image just after sundown on Feb. 22 from The Mendip Hills — a range of limestone hills in Somerset in the U.K.

Related: Have all 8 planets ever aligned?

To achieve this photographic feat, Dury created a composite shot made up of several panes, with each pane captured in multiple exposures.

To locate Saturn, Neptune and Mercury, which were dimmer and closer to the western horizon, Dury used astronomy software to generate models of the night sky and match planetary locations to nearby star fields. He then used a high dynamic range (HDR) camera setting to capture the planets' faint light.

"I noted that when I took the image that it would not, of course, be possible to photograph the lowest planets at the moment of sunset — glare from the sun rendering this task impossible," Dury said. "Therefore, this image is a record of the first possible glimpse of the planets as light from the sun diminished." The night-sky models enabled him to later identify the planets in the image.

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

These conjunctions aren't rare, but they get rarer with each planet added to the chain. For example, 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 as 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.

However, it is a little less unusual for all seven planets to appear spread out on the same side of the sun, as they do in Dury's image and in the night sky right now. Another seven-planet parade is expected to be visible from Earth in 2040.

If you'd like to see a planetary alignment for yourself, tonight (Feb. 28) is one of the best times to look. Time and Date and Stellarium are two great online tools for finding viewing times based on your location.

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.

New photos of Mercury's mysterious north pole reveal a glimpse of the permanently dark, frigid craters that may hold ice dozens of feet thick, even though Mercury is the closest planet to the sun.

Mercury's surface can reach a blistering 800 degrees Fahrenheit (430 degrees Celsius) during the day, according to NASA. But the planet lacks an atmosphere to hold that heat in — so, on Mercury, dark equals cold. At night, temperatures can plunge to minus 290 F (minus 180 C). The planet's north pole is pockmarked by craters whose bottoms are always in shadow. Research has shown that these crater bottoms likely contain thick deposits of water ice.

The new images of these cold craters come courtesy of BepiColombo, a joint mission of the Japan Aerospace Exploration Agency and the European Space Agency (ESA). The BepiColombo spacecraft will start orbiting Mercury in 2026. Right now, it's conducting a series of flybys of the planet to get into position for that orbit. On Jan. 8, one of those flybys brought the craft within 183 miles (295 kilometers) of the planet's surface. BepiColombo also passed right over Mercury's north pole.

Lands of perpetual shadow

The spacecraft sent back a series of stark images, including photos of the perpetually shadowed Prokofiev, Kandinsky, Tolkien and Gordimer craters. It also snapped photos of Borealis Planitia, where massive lava flows 3.7 billion years ago created a smooth plain, according to ESA. The pictures show Mercury's biggest impact crater, as well as a mysterious, boomerang-shaped lava flow.

Related: 10 jaw-dropping space photos that defined 2024

A third image shows Nathair Facula, a light-colored region left behind by volcanic eruptions in the planet's past. Younger areas on Mercury are lighter, according to ESA; though researchers don't know what the planet's surface is made of, it clearly darkens with age. Near Nathair Facula is another bright spot, Fonteyn crater, which formed in an impact 300 million years ago.

When the BepiColombo spacecraft enters Mercury's orbit, it will separate into two orbiters that will focus on the planet's north and south poles. Among the questions it will probe, according to ESA, is whether water ice really exists in the planet's craters and what Mercury's surface is actually made of.

Mercury may have a thick layer of diamonds hundreds of miles below its surface, a new study shows. The findings, published June 14 in the journal Nature Communications, may help solve mysteries about the planet's composition and peculiar magnetic field.

Mercury is filled with mysteries. For one, it has a magnetic field. Although it's much weaker than Earth's, the magnetism is unexpected because the planet is tiny and appears to be geologically inactive. Mercury also has unusually dark surface patches that NASA's Messenger mission identified as graphite, a form of carbon. 

That latter feature is what sparked the curiosity of Yanhao Lin, a staff scientist at the Center for High Pressure Science and Technology Advanced Research in Beijing and co-author of the study. Mercury's extremely high carbon content "made me realize that something special probably happened within its interior," he said in a statement.

Despite Mercury’s oddities, scientists suspect it probably formed the way other terrestrial planets did: from the cooling of a hot magma ocean. In Mercury's case, this ocean was likely rich in carbon and silicate. First, metals coagulated within it, forming a central core, while the remaining magma crystallized into the planet's middle mantle and outer crust. 

For years, researchers thought the mantle's temperature and pressure were just high enough for carbon to form graphite, which, being lighter than the mantle, floated to the surface. But a 2019 study suggested that Mercury's mantle may be 80 miles (50 kilometers) deeper than previously thought. That would considerably ramp up the pressure and temperature at the boundary between the core and the mantle, creating conditions where the carbon could crystallize into diamond. 

"We believe that diamond could have been formed by two processes," studyo co-author Olivier Namur, an associate professor at KU Leuven, told Live Science's sister site Space.com. "First is the crystallization of the magma ocean, but this process likely contributed to forming only a very thin diamond layer at the core/mantle interface. Secondly, and most importantly, the crystallization of the metal core of Mercury."

To investigate these possibilities, a team of Belgian and Chinese researchers, including Lin,  whipped up chemical soups that included iron, silica and carbon. Such mixtures, similar in composition to certain kinds of meteorites, are thought to mimic the infant Mercury's magma ocean. The researchers also swamped these soups with varying amounts of iron sulfide; they figured the magma ocean contained loads of sulfur, as Mercury's present-day surface is also sulfur-rich. 

Related: Uranus and Neptune aren't made of what we thought, new study hints

Using a multiple-anvil press, the team subjected the chemical mixtures to crushing pressures of 7 gigapascals — roughly 70,000 times the pressure of Earth's atmosphere at sea level — and temperatures of up to 3,578 degrees Fahrenheit (1,970 degrees Celsius). These extreme conditions simulate those deep within Mercury.

In addition, the researchers used computer models to get more precise measurements of the pressure and temperature at Mercury's core-mantle boundary, besides simulating the physical conditions under which graphite or diamond would be stable. Such computer models, according to Lin, tell us about the fundamental structures of a planet's interior. 

The experiments showed that minerals such as olivine likely formed in the mantle — a finding that was consistent with previous studies. However, the team also discovered that adding sulfur to the chemical brew caused it to solidify only at much higher temperatures. Such conditions are more favorable for forming diamonds. Indeed, the team's computer simulations showed that, under these revised conditions, diamonds may have crystallized when Mercury's inner core solidified. Because it was less dense than the core, it then floated up to the core-mantle boundary. The calculations also showed that the diamonds, if present, form a layer with an average thickness of about 9 miles (15 km).  

Mining these gems isn't exactly feasible, however. Apart from the planet's extreme temperatures, the diamonds are way too deep — about 300 miles (485 km) below  the surface — to be extracted. 

But the gemstones are important for a different reason: They may be responsible for Mercury's magnetic field. The diamonds may help transfer heat between the core and the mantle, which would create temperature differences and cause liquid iron to swirl, thereby creating a magnetic field, Lin explained. 

The results could also help to explain how carbon-rich exoplanets evolve. "The processes that led to the formation of a diamond layer on Mercury might also have occurred on other planets, potentially leaving similar signatures," Lin said. 

More clues may come from BepiColombo, a joint mission of the European Space Agency and the Japan Aerospace Exploration Agency. Launched in 2018, the spacecraft is scheduled to begin orbiting Mercury in 2025.   

Editor's note: This article was updated on Aug. 1, 2024 to include new quotes from the authors. The original article was published July 18.  

A rare and stunning photo recently captured a "parade of planets," in which six planets in our solar system appeared together in the predawn sky.

The image shows Mercury, Mars, Jupiter, Saturn, Uranus and Neptune in alignment. Mars and Saturn are clearly visible near a crescent moon, while the positions of the remaining planets, which were too distant to be seen with the naked eye, were revealed by two composite long exposures. 

Astrophotographer Josh Dury captured the planetary parade on June 1 in the early hours of the morning from The Mendip Hills — a range of limestone hills in the county of Somerset in the U.K. on June 1. 

The annotated image shows Mars and Saturn clearly visible near a crescent moon, while the positions of the remaining planets (too distant to be seen with the naked eye but faintly visible in the image) were revealed by two composite long exposures.

"I thought no better than to climb Crooks Peak at the unearthly hour of 2am," Dury told Live Science via email. "As time passed, it was a really special experience. Being able to see one planet after another rising and being present in my images was fantastic and really encapsulated a sense of perspective of our place within the solar system, let alone the universe."

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 of the cosmos on Earth — in reality the planets remain extremely far apart.

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 as 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, Live Science previously reported. 

If you'd like to see a planetary alignment for yourself, Time and Date and Stellarium are two great online tools for finding viewing dates and times based on where you are in the world.

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.

If you've never seen Mercury, now is your chance — the next two weeks offer great opportunities to view the solar system's innermost planet.

The "swift planet" — so named because it orbits the sun in just 88 days — is notoriously difficult to see because it's always very close to the sun. Most of the time, Mercury is either lost in the sun's glare or on the other side of the sun from our point of view on Earth.

Because of its proximity to our star, Mercury can be seen from Earth only during twilight, when the sun is about to rise or has recently set.

Starting next week, Mercury climbs to its highest of the year as it reaches its "greatest elongation" — the largest gap between the planet and the sun as seen from Earth. These greatest elongations happen every three or four months, before sunrise or after sunset. However, before Mercury reaches that point next week, the crescent moon visits it, which could make this elusive planet relatively easy to find.

Related: The 10 best stargazing events of 2024

To spot it, look east 30 minutes before sunrise on Monday, May 6. You'll have a chance to see a 4%-illuminated crescent moon low on the horizon. A few degrees north will be Mercury. Although the moon will make it easy to locate the tiny planet, it will be very low, so it may prove too difficult to see.

On Thursday, May 9, Mercury will reach its "greatest elongation west" of the sun and be slightly higher above due east, with Mars and Saturn above it. Although it's farthest from the sunrise on May 9, Mercury will be at its highest above the horizon on Tuesday, May 14. Using a good pair of stargazing binoculars or a nice small telescope will also help with the view.

Mercury is the only planet in the inner solar system that a robotic mission hasn't landed on. However, it has been imaged, with NASA's Mariner 10 photographing it during three flybys in 1974 and 1975 and NASA's MESSENGER mapping it from 2008 to 2015.

BepiColombo, a joint mission from the European Space Agency and the Japan Aerospace Exploration Agency, is on its way to Mercury. When it reaches the planet in December 2025, the spacecraft will insert two satellites into orbit to study the tiny planet's craters, geology and composition, as well as its atmosphere and magnetosphere.

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."

A gigantic, fiery eruption around 40 times wider than Earth recently exploded from the sun's hidden far side. The eruption hurled a massive cloud of plasma into space that later smashed into Mercury, scouring the planet's rocky surface and potentially triggering "X-ray auroras" on the unprotected world.

The eruption was likely triggered by a powerful solar flare, which occurred around 7 p.m. ET on March 9, Spaceweather.com reported. NASA's Solar Dynamics Observatory (SDO) spotted a large, partially obscured plasma filament exploding outward from behind the sun's northeast limb. Based on the amount of visible plasma, the eruption likely spanned around 310,000 miles (500,000 kilometers) across.

SDO data showed that the explosion, which likely left behind a massive "canyon of fire" on the sun's surface, also released a large coronal mass ejection (CME) — a fast-moving cloud of magnetied plasma and radiation — that collided with Mercury on March 10.

Mercury is often blasted with CMEs due to its proximity to our home star. The small planet has no atmosphere left as a result of this bombardment and is fully exposed to the full force of these solar storms. 

When electrons from CMEs hit Mercury's unprotected surface, they rapidly slow down. This deceleration causes the particles to release energy in the form of X-rays, which scientists can detect from Earth. The result is an aurora-like phenomenon that is visible in X-rays rather than visible light, according to Live Science's sister site Space.com.

Related: 10 solar storms that blew us away in 2023

The gigantic eruption is the latest sign that the explosive peak of the sun's roughly 11-year solar cycle, known as solar maximum, may have already begun — much earlier than originally forecast.

During solar maximum, solar flares and other types of solar storms erupt more frequently and more powerfully as the sun's magnetic field weakens and eventually flips over. Scientists are already seeing signs of this happening.

In the last month, researchers have seen some of the biggest solar storms of the current cycle, including a monster X-class flare — the most powerful for more than six years — and a plume of plasma 15 times taller than Earth, which erupted from the sun's south pole.

One of the biggest concerns during solar maximum is that researchers can't properly monitor the far side of the sun, which can harbor giant sunspots that unleash surprise solar storms, like the one that just hit Mercury. It's possible that these sunspots could swing round to face Earth as the sun rotates, exposing our planet to flares and CMEs. For example, in January 2023, a hidden sunspot spat out an X-class flare without warning that narrowly avoided Earth.

One secret weapon NASA has up its sleeve to prevent being caught out by these unseeable dark patches is the Perseverance rover, which can sometimes spy on the sun's far side from its home on Mars. But this only works when Earth and Mars are located on opposite sides of the sun. 

A bodiless clay head of the Roman god Mercury, discovered in England, has revealed the whereabouts of a previously unknown Roman settlement.

Archaeologists found the head at Smallhythe Place, in Kent, a site that was known for shipbuilding in medieval times. So the team was surprised to find the roughly 2,000-year-old pipe-clay head of Mercury, the Roman god of fine arts, commerce and financial success.

The "incredibly rare" head, as well as other finds from an excavation, indicate that a Roman settlement stood there between the first and third centuries, according to a statement from the National Trust, a conservation charity.

Related: A slave was brutally crucified in Roman Britain 1,700 years ago. Now, his face has been brought back to life.

Typically, Mercury figurines were crafted out of metal, making the pipe-clay — a fine, white clay used in later centuries to make tobacco pipes — discovery unexpected. At the time, most pipe-clay figurines were molded from clay that was local to central Gaul (modern-day France) and the Rhin-et-Mosell region, according to the statement. Today, archaeologists know of fewer than 10 pipe-clay figurines in Roman Britain, and most feature female deities, such as Venus, according to the statement.

During Britain's Roman period (A.D. 43 to 410), it was common for both ordinary and elite people to worship figurines depicting deities in their homes, as religion was a key part of daily life. This particular Mercury figurine, which shows Mercury wearing a hat, likely showed the god standing in one of two ways: either draped with a short cloak known as a chlamys, or naked and holding a caduceus, a staff with twisted snakes that nowadays symbolizes medicine.

The head of Mercury, as well as other finds from the site, will go on display Feb. 28 at Smallhythe Place.

If you ask an astronomer which planet is closest to Earth, you'd probably expect to get a single, simple answer in response. And if you were paying attention at school, you'd probably be reasonably confident you could guess which one of the seven other planets in our solar system it is. 

So what is the closest planet to us? Turns out there isn't just one right answer — there are technically three, depending on how you've phrased the question and when you've asked it. 

The best way to explain why this is so contentious is to go through the different possible questions and answer them, one at a time. 

Which planet gets closest to Earth?

The answer to this particular question is straightforward — Venus. At its closest proximity to Earth, the hellish planet is only around 24 million miles (38 million kilometers) away from our planet, and no other planet gets closer to us. 

Using this logic, our next nearest neighbor is Mars, which can get to within 34 million miles (54.7 million km) of our planet, followed by Mercury, which is around 48 million miles (77.2 million km) from Earth at its closest point to us. 

Related: How many times has Earth orbited the sun?

However, we're very rarely near our closest point to any of these planets, and all three of them (as well as Earth) are constantly orbiting the sun at different speeds, meaning the distances between our blue marble and each of them are constantly changing over time. As a result, most astronomers do not find this answer very satisfying. 

Which planet is closest to Earth right now?

For this question, the answer can be either Mercury, Venus or Mars, depending on where each planet is on its orbital path compared to Earth.

For example, if Venus and Mercury are located near their farthest points from Earth on the other side of the sun and Mars is near its closest point to Earth, then Mars would be the closest planet to us at that point. But if Mars is at its farthest point from Earth, and Mercury and Venus are near their closest points, then Venus would be the closest planet to us. 

But the answer to this question changes all the time, which also doesn't make it a very good way of determining our closest neighbor. 

For example, when this article was written (January 2024), the closest planet to Earth was Mercury. But in around eight months, Venus will be the closest planet to us, and in another two months or so, Mars will have surpassed Venus as our closest neighbor. However, less than a month later Venus will have wrestled back the title. 

You can keep track of this yourself using this simulator from TheSkyLive.com. 

Which planet is closest to Earth on average?

This is where things get really interesting. 

If you look online for a list of planets' average distances from Earth, you will get results saying that Venus is much closer to Earth on average than Mercury or Mars. For example, ThePlanets.org lists Venus' average distance to Earth as around 25.7 million miles (41.4 million km), compared with 57 million miles (91.7 million km) for Mercury and 48.6 million miles (78.3 million km) for Mars. 

Related: Why do the planets in the solar system orbit on the same plane?

But these lists are wrong because they are based on flawed assumptions, Tom Stockman, a research and development engineer at Los Alamos National Laboratory in New Mexico, told Live Science. To get these numbers, people have simply calculated the average distance between the radius of each planet's orbital distance from the sun, he said. But this does not take into account the planets' relative positions to one another during their orbits — it only tells you how far apart they orbit the sun on average, Stockman said.

Instead, the correct way to work out the average distances between planets is by using a point-circle method (PCM), which calculates an average of all the distances between each point on both orbits, Stockman said. 

In 2019, Stockman co-wrote an article in Physics Today that pointed out this basic error and shared the true average distances between each of the planets based on a PCM model — which the authors  named the whirly-dirly corollary after an episode of the cartoon "Rick and Morty." This revealed that Venus actually has an average distance of 105.6 million miles (169.9 million km) from Earth, while Mars is around 158.1 million miles (254.4 million km) away on average. However, Mercury is only around 96.6 million miles (155.5 million km) from Earth on average.

However, these averages still don't paint the whole picture because they only represent distance and not time. Therefore, Stockman and his colleagues ran their simulations for 10,000 years to see how long, on average, each planet was closest to Earth. This revealed that Mars spent roughly 17% of the time as Earth's closest neighbor and Venus spent roughly 36% of the time holding the title. But the winner was Mercury, which was closest to Earth for roughly 47% of the time, making it our true closest neighbor on average.

Mercury is our closest companion because it is the closest to the sun and has the smallest orbit, which means it is more often on the same side of the sun as Earth, and even when it's not, it's never that far away. Meanwhile, Venus and Mars spend long periods of time much farther away from Earth.

For the same reason, it turns out that not only is Mercury our closest neighbor on average, but it is also the closest average neighbor of all six other planets in our solar system, the whirly-dirly corollary revealed.

Before the whirly-dirly corollary, other astronomers had probably already figured all this out, meaning it wasn't "entirely unknown," Stockman said. "I think most people that knew, like me at first, just treated this as a fun little fact to talk about at parties," he added. 

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.

Planetary scientists have discovered salty glaciers near the north pole of Mercury, raising the possibility that the closest planet to the sun may be capable of hosting life. The new findings, which were made using past observations from NASA's retired MESSENGER probe, were published in The Planetary Science Journal in November.

"Our finding complements other recent research showing that Pluto has nitrogen glaciers, implying that the glaciation phenomenon extends from the hottest to the coldest confines within our Solar System," lead study author Alexis Rodriguez, a planetary scientist at the Arizona-based nonprofit Planetary Science Institute (PSI), said in a statement.

These glaciers, found in Mercury's Raditladi and Eminescu craters, aren't quite like the typical icebergs we think of on Earth. Instead, they're flows of salt that trapped volatile compounds deep below Mercury's surface. In geology terms, volatiles are chemicals that readily evaporate on a planet — like water, carbon dioxide and nitrogen. Mercury's strange salt-bergs were revealed by asteroid impacts, which exposed this material trapped below the surface; that's why scientists discovered them in craters.

Glaciers are surprising to find on Mercury because of its proximity to the sun; the planet is 2.5 times closer to our star than Earth is. At that small distance, things are a lot hotter. Yet, these salt flows could have preserved their volatiles for "over one billion years," according to study co-author Bryan Travis, also a planetary scientist at PSI.

Although Mercury's salty deposits aren't analogous to typical icebergs or Arctic glaciers, similarly salty environments do exist on Earth, so geologists have a good idea of what these environments are like — and whether life can emerge there.

"Specific salt compounds on Earth create habitable niches even in some of the harshest environments where they occur, such as the arid Atacama Desert in Chile," Rodriguez said. "This line of thinking leads us to ponder the possibility of subsurface areas on Mercury that might be more hospitable than its harsh surface."

With volatiles — which are necessary for life, especially water — trapped underground, Mercury might be able to sustain subterranean life sheltered from the harsh rays of the sun. Just as planetary systems have "Goldilocks zones" — regions around their star where liquid water can persist — might have a similar "potentially habitable" region below its surface, the researchers suggested. And if Mercury could host life, then exoplanets similar to Mercury might become more enticing to scientists who are hunting for alien life.

The discovery of these glaciers also helps to explain a long-standing mystery about Mercury: craters with chunks missing. The researchers propose that the little pits observed dotting some craters used to be filled with volatiles, before the impact exposed them and they evaporated.

One big question remains: How did the volatile layers get there in the first place? Observations of Mercury's north pole suggest the volatiles were deposited on top of a fully formed landscape. Rodriguez suggested they could come from "the collapse of a fleeting, hot primordial atmosphere early in Mercury's history."

Alternatively, maybe Mercury had lakes, co-author Jeffrey Kargel, also at PSI, proposed. Perhaps "a dense, highly salty steam" leaked out of the volcanic interior of young Mercury and then evaporated, leaving the salt behind, he said.

Further studies are needed to truly shine a light on what may lurk below Mercury's surface.

The smallest planet in the solar system is getting even smaller. Mercury, the closest planet to the sun, has been cooling down and contracting for millennia, creating gigantic scars on its surface (known as lobate scarps) as the rocky surface buckles from the shrinkage.

Geologists weren't sure when exactly these scarps formed, or if Mercury's still making new ones as it continually cools — until now. New research published Oct. 2 in the journal Nature Geoscience took a closer look at the scarps, and found small cracks indicating that they must have moved in the last 300 million years.

"Our team found unambiguous signs that many scarps have continued to move in geologically recent times, even if they were initiated billions of years ago," study co-author David Rothery, a geologist at The Open University in the U.K., wrote in an article for The Conversation. "This is like the wrinkles that form on an apple as it ages, except that an apple shrinks because it is drying out," whereas Mercury shrinks because it's cooling down, Rothery added.

Related: See Mercury's giant, comet-like tail in stunning new image as it passes close to the sun

The team's new up-close view was provided by NASA's Messenger spacecraft, which orbited Mercury for over a decade from 2004 to 2015. The team spotted grabens, the geological term for small cracks parallel to a fault line, right next to the lobate scarps. Grabens form from the fault lines trying to bend a piece of stiff rock. "If you try to bend a piece of toast, it may crack in a similar way," Rothery wrote. The team found 48 confirmed grabens, and a whopping 244 more features likely to be grabens.

They dated these rocks using information about "impact gardening" — how quickly the dust generated from meteor impacts blur out features on Mercury's surface. Based on how blurry the grabens appeared in images, the team calculated they're about 300 million years old.

The movements of the scarps not only generate the grabens, but can cause "Mercury-quakes" — quite similar to shaking we've measured on the moon and termed "moonquakes". The moon is shrinking and wrinkling just like Mercury, and there we've got lunar seismometers on the ground to prove it.

Unfortunately, there's no such equipment on Mercury, but the upcoming European BepiColombo mission will start orbiting the tiny planet in 2025, hopefully providing more information about Mercury's geology — including a high-definition view of its wrinkles. "Its most detailed images might reveal boulder tracks that could be additional evidence of recent quakes," Rothery wrote. "I am looking forward to finding out."

If you've never seen the smallest planet in our solar system with your own eyes, then this weekend brings an excellent opportunity.

On Friday, Sept. 22, Mercury will reach its highest point in the sky all year while becoming half-lit.

Also known as the 'Swift Planet' for its brisk 88-day orbit around the sun, Mercury orbits so close to our star that it's almost always lost in the sun's glare. The planet is technically present in the daytime sky almost all year yet is impossible to see. Only occasionally does it become visible in twilight close to sunrise or sunset on Earth.

That's what will happen this coming week with Mercury's 'greatest elongation,' which refers to a point in its orbit when Mercury  appears farthest from the sun, as seen from Earth. Its greatest elongation east is when it's visible above the western horizon just after sunset while its greatest elongation west marks its visibility above the eastern horizon just before sunrise. The planet will also appear half-lit — known as its 'dichotomy' — much like the moon at its first or last quarter phase.

Mercury's greatest elongation west will occur on Sept. 22, though it will be well placed for viewing before sunrise all week, getting as high as 17 degrees above the eastern sky. According to In-The-Sky.org, it will be brighter and easier to see in the days after it reaches its highest point in the sky when it will show a gibbous phase — appearing more than half-lit. According to Space.com, Mercury will be at its brightest and easiest to spot in the morning sky from Sept. 16 to Sept. 30.

It will be best seen about 30 minutes before sunrise from Sept 22. through early next week. You'll need a clear, unobstructed horizon. A pair of stargazing binoculars would also be useful to spot Mercury, which typically has a yellow tinge. You can find the exact time of Mercury's rise for your location using TimeAndDate.com's Night Sky Map & Planets Visible Tonight page. Venus will be shining brightly above, with the bright star Regulus in the constellation Leo between the two planets.

Mercury's next greatest elongation east will come on Dec. 4, 2023, when it will be visible in the evening after sunset.

In early July, the moon will pass close to all three of Earth's neighboring  inner solar system planets, plus the two largest planets that orbit the sun.

First, the gas giants Saturn and Jupiter will be viewable next to the moon before sunrise early in the month. Later in July, Mercury, Venus and Mars will shine close to a crescent moon after sunset.

All five planets and Earth's moon will be easily visible to the naked eye from anywhere in the world with clear skies. However, a good pair of stargazing binoculars or a nice small telescope will enhance the view. 

The first conjunction (a celestial event in which two objects appear close together in Earth's night sky) of the moon and a planet will occur on July 7, when an 80%-lit waning gibbous moon will be visible just below Saturn. The two objects will rise in the southeastern night sky in the early morning and will be visible until dawn. 

On July 11, a 37%-lit waning gibbous moon, positioned slightly above Jupiter, will rise in the east late at night. The following morning, the moon will have waned to 27% illumination and will be visible just below Jupiter. 

Mercury, Venus and Mars — the other three rocky planets in the solar system — will be closely grouped with a slender waxing gibbous crescent moon in the early-evening western night sky from July 19 to July 21. 

Because the crescent moon will be barely 5% lit on July 19, however, this will be the hardest night to see it close to the rocky planets. That will also be true for Mercury, which will be very low on the horizon. However, bright Venus will be obvious alongside the crescent moon, while Mars will be easily seen above. Don't mistake Mars for Regulus, the brightest star in Leo, which will sit between Venus and Mars. Use binoculars, find a clear view toward the western horizon and begin looking about 35 minutes after sunset, according to When The Curves Line Up, a site run by astronomer Jeffrey Hunt.

On July 20 — the 54th anniversary of Apollo 11, the first moon landing — the crescent moon will be much easier to see. As well as being 10% lit, the moon will have climbed higher and will shine alongside Mars, just above Venus. Mercury will remain low on the west-northwest horizon. While you're gazing at the trio of planets, look for "Da Vinci glow" on the dark limb of the moon. Also called Earthshine, the phenomenon is caused by reflected sunlight from Earth's oceans, clouds and ice. 

The following evening, July 21, a 16%-lit crescent moon will appear even higher above the western horizon, but it will be aligned with Mars and Venus. Mercury will be to the right of Venus. 

On the following nights, the moon will depart the scene and climb higher into the post-sunset sky, with Venus sinking into the sun's glare while Mercury continues to rise above it. On July 28, Mercury will shine within just a tenth of a degree of Regulus in twilight, according to Adler Planetarium. It should be an excellent sight, even to the naked eye. 

You can check the exact rise and set times for the planets for your location using the Night Sky page on timeanddate, or planetarium software such as Stellarium Web Online Star Map. 

Earth probably shouldn't exist. 

That's because the orbits of the inner solar system planets — Mercury, Venus, Earth and Mars — are chaotic, and models have suggested that these inner planets should have crashed into each other by now. And yet, that hasn't happened.

New research published May 3 in the journal Physical Review X may finally explain why. 

Through a deep plunge into the models for planetary motion, the researchers discovered that the motions of the inner planets are constrained by certain parameters that act as a tether that inhibits the system's chaos. Besides providing a mathematical explanation for the apparent harmony in our solar system, the new study's insights may help scientists understand the trajectories of exoplanets surrounding other stars. 

Unpredictable planets

Planets constantly exert a mutual gravitational pull on each other – and these little tugs constantly make minor adjustments to the planets' orbits. The outer planets, which are much larger, are more resistant to little tugs and so maintain comparatively stable orbits. 

The problem of inner planet trajectories, however, is still too complicated to solve exactly. In the late 19th century, mathematician Henri Poincaré proved that it is mathematically impossible to solve the equations governing the motion for three or more interacting objects, often known as the "three body problem." As a result, uncertainties in the details of the planets' starting positions and velocities balloon over time. In other words: It is possible to take two scenarios in which the distances between Mercury, Venus, Mars and Earth differ by the slightest amount, and in one the planets smash into each other and in another they veer apart. 

The time it takes for two trajectories with almost identical starting conditions to diverge by a specific amount is known as the Lyapunov time of the chaotic system. In 1989, Jacques Laskar, astronomer and research director at the National Center for Scientific Research and Paris Observatory and a co-author of the new study, calculated the characteristic Lyapunov time for the planetary orbits of the inner solar system was just 5 million years. 

"It means basically that you lose one digit every 10 million years," Laskar, told Live Science. So, for example if the initial uncertainty in the position of a planet is 15 meters, 10 million years later this uncertainty would be 150 meters; after 100 million years, a further 9 digits are lost, giving an uncertainty of 150 million kilometers, equivalent to the distance between Earth and the sun. "Basically you have no idea where the planet is," said Laskar.

While 100 million years may seem long, the solar system itself is over 4.5 billion years old, and the lack of dramatic events — such as a planetary collision or a planet being ejected from all this chaotic motion — long puzzled scientists. 

Laskar then looked at the problem in a different way: by simulating the inner planet trajectories over the next 5 billion years, stepping from one moment to the next. He found just a 1% chance of a planetary collision. With the same approach, he calculated that it would take, on average, about 30 billion years for any of the planets to collide. 

Reining in the chaos

Delving through the math, Laskar and his colleagues then identified for the first time "symmetries" or "conserved quantities" in the gravitational interactions that create a "practical barrier in the chaotic wandering of the planets," Laskar said. 

These emergent quantities remain nearly constant and inhibit certain chaotic motions, but don't prevent them altogether, much like the raised lip of a dinner plate will inhibit food falling off the plate but not prevent it completely. We can thank these quantities for our solar system's apparent stability.

Renu Malhotra, Professor of Planetary Sciences at the University of Arizona who was not involved in the study, highlighted how subtle the mechanisms identified in the study are. Malhotra told Live Science that it is interesting that "our solar system's planetary orbits exhibit exceptionally weak chaos." 

In other work, Laskar and colleagues are searching for clues as to whether the number of planets in the solar system ever differed from what we currently see. For all the stability evident today, whether that has always been the case over the billions of years before life evolved remains an open question. 

Mercury has been spotted cosplaying as a comet over the last few days when the sun's neighboring planet reached its nearest point to our star, exposing its massive, streaking tail in the night sky. One astrophotographer captured a truly epic shot of the charade. 

Comets are orbiting chunks of frozen rocks, gases and dust that are almost always seen with distinctive twin tails trailing behind them — one made of gas that leaks from their interiors and another created by dust from their surfaces. These two tails are blown away from the comet in the same direction by charged particles from the sun known as solar wind. 

Mercury, the solar system's smallest planet, has one comet-like tail made predominantly of sodium ions, which are scattered from the planet's surface by solar wind and micro-meteor impacts. Researchers have known about Mercury's tail since 2001 and have since discovered that it grows and shrinks based on the planet's proximity to the sun. At its peak, the tail stretches to around 14.9 million miles (24 million kilometers) long, according to Spaceweather.com, which is around 62 times greater than the distance between Earth and the moon. The tail stretches this huge distance because Mercury has a very weak atmosphere and is close to the sun, which makes it easy for the solar wind to rip up the planet's surface. 

Related: Optical illusion gives rare green comet an 'anti-tail' that seemingly defies physics

For unknown reasons, Mercury's tail is most visible from Earth exactly 16 days after perihelion, or the point at which the planet is closest to the sun, according to Spaceweather.com. Mercury reached perihelion on April 1, meaning its tail appeared brightest on April 17. But on April 12, astrophotographer Sebastian Voltmer captured a stunning image of the planet's tail from a spot near Spicheren, a commune in northeastern France. 

To a casual observer, Mercury's tail is very hard to see, which is why it went undiscovered until the 21st century. But Voltmer was able to photograph the giant plume thanks to a specialized filter that highlights yellow wavelengths of light, which are given off by the excited sodium particles in the tail. 

"Without such a filter, Mercury's tail is almost invisible to the naked eye," Voltmer told Spaceweather.com. 

Mercury is not the only celestial body in the solar system with a surprisingly comet-like tail. The moon also has a tail that is only visible once a month as Earth passes through it and wears it like a scarf. Like Mercury, the moon's tail is also predominantly made of millions of sodium atoms. 

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. 

Astronomers have detected a blob of hot gas whizzing around the supermassive black hole at the heart of our galaxy at an extraordinary speed. A powerful magnetic field surrounding the colossal space-time tear has supercharged the bizarre gaseous globule, speeding it up to 30% the speed of light, a new study finds. 

The supermassive black hole at the center of the Milky Way, known as Sagittarius A*, is around 4 million times more massive than the sun and stretches around 40 million miles (60 million kilometers) across. Normally, anything that gets too close to such a massive black hole gets dragged beyond its event horizon by an overwhelming gravitational pull. But the newly discovered gas blob, or hot spot, is moving so quickly that it appears to have formed a stable orbit around the massive cosmic void. 

The gaseous blob's orbit around Sagittarius A* is equivalent in size to the orbit of Mercury around the sun. But the blazing blob completes a full rotation around the black hole every 70 minutes, compared with the 88 days it takes Mercury to travel the same distance, researchers wrote in a new paper published online Sept. 22 in the journal Astronomy and Astrophysics.

"This requires a mind-blowing velocity of about 30% of the speed of light," study lead author Maciek Wielgus, an astronomer at the Max Planck Institute for Radio Astronomy in Germany, said in a statement. That's around 201.2 million mph (323.8 million km/h), or around 3,000 times faster than Earth moves around the sun.

Related: Are black holes wormholes? 

Researchers first spotted the orbiting blob in 2017 using the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile. The ALMA telescope, which is made up of 66 antennae, is one of eight telescopes that make up the Event Horizon Telescope (EHT) network, which produced the first direct image of Sagittarius A* in May this year. 

Researchers were calibrating ALMA to focus on Sagittarius A* for the EHT project when they detected an unusual X-ray flare coming from the space surrounding the black hole. 

The electromagnetic radiation from the flare, which was also visible in infrared and radio, was highly polarized, or twisted, and showed signs of synchrotron acceleration — in which an object is subject to an acceleration perpendicular to its velocity. This type of acceleration occurs when charged particles are propelled forward by a strong magnetic field, like how artificial particle accelerators supercharge electrons, according to ScienceAlert. 

The only explanation for this type of acceleration is that the flare originated from the black hole's magnetically arrested disk — a ring of matter surrounding a black hole that is being held in place by a strong magnetic field, which counterbalances the forces of gravity pulling the matter into the cosmic void. Researchers, therefore, deduced that the only possible origin of the flare was a supercharged gas blob trapped within this disk.

Different research groups have detected similar signals from hot spots rapidly orbiting other black holes, according to the statement. However, this is the first time that a flare emitted by a hot spot have been observed in radio as well as infrared and X-ray, the researchers wrote in the paper.

The researchers think that the radio waves they detected could mean that the hot spot is slowing down and losing some of its energy, according to the statement. This could potentially signal that the gas blob will eventually slow down enough for the black hole's gravity to overcome the magnetic shielding surrounding it and finally pull the gas into its infinite maw. 

The researchers hope that this new information can be used to help track additional hot spots around other black holes. 

"In the future, we should be able to track hot spots across frequencies using coordinated multiwavelength observations," study co-author Ivan Marti-Vidal, a radio astronomer at The University of Valencia in Spain, said in the statement. "The success of such an endeavor would be a true milestone for our understanding of the physics of flares in the galactic center." 

Related: Do black holes explode?

While the new study improves our understanding of the Milky Way's black hole heart, researchers said there is still a lot more to learn about Sagittarius A*.

Until now, telescopes have struggled to focus in on the supermassive structure because it frequently flares up, shooting out electromagnetic radiation that interferes with delicate sensors. But the new James Webb Space Telescope will play a key role in future research into Sagittarius A* because it will be able to see past this interference.

"Hopefully, one day, we will be comfortable saying that we 'know' what is going on in Sagittarius A*," Wielgus said. But that day is not today.

Originally published on Live Science.

The early bird catches the spectacular skywatching this week, as five planets march across the predawn sky. 

This rare planetary alignment has been visible since early June. But the view should be particularly impressive this week, as Mercury is at its brightest and the waning moon joins the parade of planets. 

"This is early morning, so you do have to set the alarm in order to do it — but it's just a fun time to go see planets in the sky," Michelle Nichols, director of public observing at Chicago's Adler Planetarium, told Live Science. 

Related: 4 planets line up like ducks in a row in gorgeous night-sky image

How to watch the five-planet alignment

The alignment is visible just before dawn in the Northern Hemisphere. The best time to look is about 45 minutes before sunrise, local time, Nichols said. 

The planets will be spread from the east-northeast horizon, arcing toward the south. Coincidentally, they'll be lined up in their order from the sun: Mercury, Venus, Mars, Jupiter and Saturn.  This particular planetary configuration hasn’t occurred since 1864, Live Science sister site Space.com reported. Saturn is the earliest of this quintuplet to rise and will be visible in the southeast sky just before dawn, in the constellation Capricornus. Jupiter, in the constellation Pisces, will be visible as a very bright body next door; it will appear more than twice as bright as Sirius, the brightest star in the sky, according to Space.com. 

Mars is one of the easier planets to pick out because of its reddish coloring; it will be above the eastern horizon. Venus, appearing even brighter than Jupiter, will rise over the horizon, to the left of Mars. Mercury will be the last to make an appearance in the 40 minutes or so before sunrise, peeking over the horizon to the left of Venus. 

On June 27, the crescent moon will provide a useful signpost for Mercury, which will be just below and to the right of the crescent. Mercury will also hover near an orange-tinted star called Aldebaran, which makes up the eye of the bull in the constellation Taurus. 

A helpful tip for picking out planets is to look for steady light, Nichols said. Stars twinkle, but planets don't. 

Adding to the drama, the moon will be swooping across this band of planets throughout the week. On Wednesday (June 22), the moon will be to the right of Mars. From June 23 to 25, it will perch between Mars and Venus, becoming a skinnier crescent each night. Break out the binoculars before dawn on June 27, according to Space.com, and you might catch the last 3% sliver of the moon sitting to the left of a relatively bright Mercury. 

What is a planetary alignment?

The visible planets are not actually lined up in space, but they do all happen to be on one side of the sun. From Earth, a lack of depth perception makes the planets look like they are next to one another. 

Mercury circles the sun every 88 Earth days, Venus every 225 days, Mars every 687 days, Jupiter every 12 years and Saturn every 29 years, so these alignments occur on an irregular schedule. The last time the five visible planets were aligned was in 2020, preceded by 2016 and 2005. 

The alignment will be visible even in the presence of light pollution, but some of the planets — especially Mercury — are low to the horizon, so look for a viewpoint with a clear southern and eastern horizon, such as a shoreline or another flat spot. 

Originally published on Live Science

It's officially summer in the Northern Hemisphere, and half of the solar system wants to get in on the action. For the remainder of June, stargazers taking the red-eye shift will be able to see five planets line up in the predawn sky: Mercury, Venus, Mars, Jupiter and Saturn. Remarkably, the planets will appear in order of their proximity to the sun, with Mercury visible closest to the horizon while the other planets arc neatly across the southern and eastern sky.

From Thursday (June 23) to Saturday (June 25), Earth's moon will also join the planetary parade, creating an exceptionally rare procession of celestial bodies. According to Live Science's sister site Space.com, a planetary alignment like this hasn't occurred since March 5, 1864 — 158 years ago.

While this five-planet alignment has been visible for much of June, the view improves significantly during the last few weeks of the month, Space.com added. The show begins a bit after midnight when Saturn becomes visible to the naked eye, followed by Jupiter, Mars and Venus over the following hours. Roughly 30 minutes before sunup, Mercury finally joins the party, completing the epic alignment. 

From June 23 to June 25, a small crescent moon will sneak between Venus and Mars, as if standing in for Earth in the predawn planetary lineup. 

To get the best view of the alignment, stargazers should find a spot with a clear view of the horizon toward the east, according to NPR. Binoculars or a telescope are recommended. If you miss the alignment this year, you won't have another chance to see the five planets line up in sequential order until 2040, NPR added.

After June, the planets will gradually start to go their separate ways, with Saturn, Mars, Jupiter and Venus starting to appear more spread out in the sky, according to NASA. By September, Venus and Saturn will no longer be visible to most observers in the morning hours — so catch them while you can.

Originally published on Live Science.

A planetary alignment that has been developing for months is finally here. 

Depending on local viewing conditions, Mercury may now be visible alongside Venus, Saturn, Mars and Jupiter in a march across the predawn sky, visible from the Northern Hemisphere. It's the first alignment of the five visible planets in our solar system since 2020. 

"This is early morning, so you do have to set the alarm in order to do it, but it's just a fun time to go see planets in the sky," Michelle Nichols, the director of public observing at Chicago's Adler Planetarium, told Live Science. 

How to see the five-planet alignment 

The alignment will be spread out across the eastern horizon, as seen from the Northern Hemisphere. The best time to view the alignment is about 45 minutes before sunrise, local time, Nichols said. The clock time for sunrise will vary day to day and within time zones, so it's best to set the alarm based on local conditions. 

Whether Mercury has joined the alignment yet also depends on local conditions. If you can find a spot with a clear view of a flat eastern horizon, the planet should be visible as of about June 10, Nichols said. If hills, mountains or buildings block the eastern view, skywatchers should hang tight for another week or two; Mercury will continue to rise higher above the horizon in the predawn hours each day. Late June is the best time to look, as Mercury will dip below the horizon again in early July. 

The planets will be spread across a wide stretch of sky from the east to the south. When trying to differentiate planets from stars, look for steady light. Generally, Nichols said, stars twinkle, while planets don't. 

"Mercury will be farthest to the east and lower, Venus will be really bright and up above it and to the right, Mars will be orange to the southeast, Jupiter will be to the upper right and then Saturn will be to Jupiter's upper right a little bit toward the south," Nichols said.

On June 27, the crescent moon will provide a useful signpost for Mercury, which will be just below and to the right of the crescent. Mercury will also hover near an orange-tinted star called Aldebaran, which makes up the eye of the bull in the constellation Taurus. 

Mercury, Venus, Saturn, Mars, and Jupiter will all be bright enough to see with the naked eye. Uranus is also in the line of planets, but will require dark skies and a pair of binoculars to spot. Neptune will be present in the morning sky in the constellation Aquarius during this time, but will not be visible except with a telescope. 

What is a planetary alignment? 

The visible planets are not actually lined up in a row in space; a viewer looking at the solar system from above would see a random smattering of planets that just all happened to be to one side of the sun. From Earth, though, a lack of depth perception makes it appear that all of the planets are next to one another. 

Mercury circles the sun every 88 Earth days, Venus every 225 days, Mars every 687 days, Jupiter every 12 years, and Saturn every 29 years, so these alignments occur on an irregular schedule. The last time the five visible planets were aligned was in 2020, preceded by 2016 and 2005. 

The timing of the alignment is limited by Mercury, which doesn't spend very long in one area of the sky, given its short orbit around the sun, Nichols said. 

"It's just a great time to go out and see the planets all at once," Nichols said. "We don't always get this opportunity." 

Originally published on Live Science

Mercury is the closest planet to the sun and the smallest planet in our solar system. With a diameter of about 3,032 miles (4,880 kilometers), Mercury is less than half the size of Earth, which is about 7,926 miles (12,756 km) in diameter. But what Mercury lacks in size, it makes up for in speed: It orbits the sun faster than any other planet in the solar system. 

How did Mercury get its name?

The planet is named after the Roman deity Mercury, the speedy messenger of the gods, who was the Roman equivalent of the Greek god Hermes. Mercury orbits our sun every 88 days — faster than any other planet in the solar system — and a year on Mercury is less than three Earth months. This swift orbit inspired the ancient Romans to associate the small planet with Mercury, according to Cool Cosmos, a website run by the Infrared Processing and Analysis Center at the California Institute of Technology, while the ancient Greeks associated the planet with Hermes, according to the European Southern Observatory.

Mercury is visible in the night sky without a telescope and has been known to humans around the world for thousands of years. The Sumerians made one of the earliest known records of the planet in around 3,000 B.C., according to Cool Cosmos.  

Is Mercury the hottest planet?

As Mercury is the closest planet to the sun, you might think it's the hottest planet. However, Mercury lacks an atmosphere like Earth's that can trap and hold heat, so the side facing away from the sun is always very cold — especially as it takes about 59 Earth days for the slow-spinning Mercury to complete a rotation. Temperatures on the surface of Mercury can still reach a toasty 800 degrees Fahrenheit (427 degrees Celsius) on the day side but can fall to as low as minus 290 F (minus 179 C) on the night side, according to NASA. 

Venus, the second planet from the sun, is the hottest planet because it has a dense atmosphere that retains heat from the sun's rays. Venus has a surface temperature of about 860 degrees Fahrenheit (462 degrees Celsius) and stays that hot on both the day and night sides, Live Science previously reported. 

Related: The sun has blasted Mercury with a plasma wave

What is Mercury made of?

Mercury is largely composed of iron, according to the Natural History Museum in London, U.K. It has an inner core with a liquid metal outer core and is encased in a mantle and crust, just like Earth. Mercury's inner core is solid and close in size to Earth's, despite Mercury being a much smaller planet overall, a 2019 study published in the journal Geophysical Research Letters found.

Instead of a full atmosphere, Mercury has an exosphere — the name given to only the thin outer layer of Earth's atmosphere. Mercury's exosphere is formed by solar wind and meteoroid strikes blasting atoms off its surface, according to NASA. The exosphere gives Mercury llittle protection from objects like asteroids and the planet is pockmarked with craters, so much so that Mercury looks similar to Earth's moon. There are no moons orbiting Mercury because it's so close to the sun that the sun's gravity likely pulls them away, according to the Natural History Museum in London.

What is Mercury retrograde?

Mercury retrograde is when the planet appears to be, but is not actually, moving backward in the sky. It's an optical illusion caused by humans' perspective of seeing the smaller planet catch up and pass Earth as it curves around the sun, Live Science previously reported. Some astrologists associate Mercury in retrograde with disruptions to daily life on Earth, but there's no scientific evidence for this. 

"The idea that the gravity from these very distant bodies affects our lives in some way just doesn't work in the framework of physics," Jean-Luc Margot, a professor of astronomy and planetary science at the University of California, Los Angeles, previously told Live Science.  

The retrograde illusion happens with other planets that Earth passes, and it's not that rare. The Mercury retrograde periods in 2022 are Jan. 13 to Feb. 3, May 10 to June 2, Sep. 9 to Oct. 1, and Dec. 28 to Jan. 18 (2023), according to The Old Farmer’s Almanac. 

Related: Mercury probe snaps stunning photos of our planet during Earth flyby 

Is there life on Mercury?

Scientists still have much to learn about Mercury, but they have no reason to think it harbors life. Mercury's searing and freezing temperatures, as well as its abundance of solar radiation, are likely too extreme for any living organisms to handle, according to NASA. Furthermore, thanks to probes like the MESSENGER (Mercury Surface, Space Environment, Geochemistry, and Ranging) spacecraft, about 98% of the surface of Mercury has been photographed in detail, according to the MESSENGER website. 

MESSENGER confirmed evidence of frozen water on Mercury in 2011. The ice is congregated at the poles in craters so it is shielded from the sun's rays. Much of this ice may have been carried to Mercury on asteroids. However, a 2020 study published in the Astrophysical Journal Letters found that mercury could be creating up to 10% of its own ice.

Here's how: Mercury's surface has minerals with groups of bonded oxygen (O) and hydrogen (H) atoms called hydroxyls, which can become energized in the sun's extreme heat and collide to create water (H2O) molecules. While the sun also breaks down these molecules, some drift around the planet and end up in freezing-cold craters at the poles to form ice, Live Science's sister site Space.com previously reported.  

"It's a little like the song ‘Hotel California.’ The water molecules can check in to the shadows, but they can never leave," study principal investigator Thomas Orlando, a professor at the Georgia Institute of Technology's School of Chemistry and Biochemistry, said in a statement at the time.  

Additional resources

To view an image gallery of Mercury taken by probes, check out NASA's Jet Propulsion Laboratory website. To learn more about the illusion of Mercury retrograde, watch this short YouTube video by Vox. For more information about the MESSENGER probe mission, visit NASA's in-depth MESSENGER page.

Originally published on Live Science.

The moon is leading a parade of planets across the predawn sky this week. And Italian astrophysicist Gianluca Masi captured the celestial show in a gorgeous image shot from his balcony in Rome. 

In advance of an unusual alignment of the five visible planets in the solar system, four planets are lining up behind the moon like ducks in a row. Since April 23, Saturn, Mars, Venus and Jupiter have all been visible above the horizon in the early morning hours in the Northern Hemisphere. 

"This morning I could enjoy the planetary parade involving Jupiter, Venus, Mars and Saturn, plus the moon. It was an amazing sight, all the four planets were very easy to see," Masi told Live Science in an email.

The night-sky photo is a precursor to a bigger planetary parade this summer, as Mercury will join the line-up in mid-June. 

When the planets align

Planetary alignments occur when the planets' orbits bring them to the same region of the sky, when viewed from Earth. These planetary alignments are not rare, but they're not regularly occurring, either: The last time five planets aligned in the night sky was in 2020, preceded by alignments in 2016 and 2005. 

These alignments take time to develop. Venus, Mars, and Saturn have been night-sky neighbors since late March. On April 4 and 5, they came so close together, when viewed from Earth, that Mars and Saturn appeared less far apart than the width of the full moon in the southeast early morning sky. 

Related: Photos: Magnificent views of the nighttime heavens in America's 'Dark Sky' parks

Jupiter turned the trio into a foursome in mid-April. Then the moon appeared in its last quarter phase to Saturn's right on April 23. Mars looks like an orange dot below and to the left of Saturn, while Venus is a brighter light below and to the left of Mars. Jupiter is the lowest and leftmost in the sky.

The way to tell the planets from the stars in the sky is by the light, said Michelle Nichols, the director of public observing at Chicago's Adler Planetarium.

"Stars twinkle," Nichols told Live Science. "Planets don't."

Watching the planetary alignment

The planets will be most visible in the northern hemisphere an hour to 45 minutes before sunrise. The moon will remain above the horizon until April 29, but the four planets will remain in their cosmic line until early July. Mercury will appear in the line as early as June 10 in places with a flat, eastern horizon (think Denver or the coast of North Carolina, looking out over the ocean), leading to the final five-planet alignment. The planets will appear to march from the east to the south, Nichols said. Late June will provide the best viewing conditions for the alignment. 

Uranus and Neptune will also be in the field of view in the Northern Hemisphere during the alignment. Uranus will be between Mercury and Mars and will be visible in areas without much light pollution. It might be possible to see it with the naked eye in a dark-enough sky, but binoculars will aid in observing it, Nichols said. Neptune will require a telescope to view. 

"It's just a great time to go out and see the planets," Nichols said. 

Originally published on Live Science.

Editor's note: This article was first published on April 20, 2022, and updated on April 26.

Five planets, visible to the naked eye, are poised to line up and march across the sky this summer in an unusual alignment that will be graced by the light of the moon. 

Alignments of the five planets visible without the aid of telescopes or binoculars occur irregularly only every few years. The last time it happened was in 2020 and, before that, in 2016 and 2005, Michelle Nichols, director of public observing at Chicago's Adler Planetarium, told Live Science. Skywatchers can already see the parade of planets getting into place, but all five will be visible from late June to early July. 

"We don't always get this opportunity," Nichols said. "Sometimes, it's one or two in the sky; a lot of times, it's none." 

When will the planets align? 

The planets aren't really in a line in space; alignments are a trick of perspective. The planets orbit the sun on a flat plane, so when they happen to be passing near each other, they look, from Earth's perspective, to be in line. An observer looking down at the solar system from above wouldn't see a straight line at all. 

Related: Why do the planets orbit the sun on the same plane?

Mercury circles the sun every 88 Earth days, Venus every 225 days, Mars every 687 days, Jupiter every 12 years and Saturn every 29 years. Given these varied timelines, the planets' orbits bring them near one another at irregular intervals. 

As seen in the northern hemisphere, Venus, Saturn and Mars began to cluster in late March 2022, though whether they're far enough above the horizon to view before sunrise depends on your location. Observers farther east and south in North America will have views in the wee hours of the morning, while those in the Pacific Northwest won't see the cluster rise until about an hour before sunrise. 

Around April 17, Jupiter will join the line of Venus, Mars and Saturn. The moon will move into this planetary conga line on April 23, appearing to the right and above Saturn, before moving out of view on April 29, when it will appear too close to the sun to be seen. The moon will rejoin the planetary alignment starting May 21. 

Finally, around mid-June, Mercury will zip into place alongside the other four planets, Nichols said, with Earth's moon joining the party on June 17. Coincidentally, the planetary line will be in the order of the planets' distance from the sun. 

"Mercury will be farthest to the east and lower, Venus will be really bright and up above it and to the right, Mars will be orange to the southeast, Jupiter will be to the upper right and then Saturn will be to Jupiter's upper right, a little bit toward the south," Nichols said. 

How to see the planetary alignment 

The best day to see the alignment varies based on local circumstances. In a place with a flat horizon off to the east, Mercury will be visible as early as about June 10, Nichols said, but viewers with a more obstructed view may have better luck waiting until late June for a peek. The alignment will be visible into early July, when Mercury will again dip below the horizon. 

Because of its short orbit, Mercury "doesn't spend a whole lot of time in one part of the sky," Nichols said.

For people in North America, the best way to see the alignment is to go outside and look to the south and east about 45 minutes before dawn local time in late June, Nichols said. Mercury, Venus, Mars, Jupiter and Saturn will all be visible to the naked eye. Also in the sky, though far more difficult to see, will be Uranus and Neptune. Uranus will likely be visible with a pair of binoculars in areas with little light pollution, Nichols said, but seeing Neptune will require the use of a 6-inch telescope. 

To tell the planets from the surrounding stars, look for steady light. The light from planets is less affected by Earth's atmosphere than the light from stars is, Nichols said. 

"The rule of thumb generally is, stars twinkle; planets don't," she said. 

There will also be some obvious landmarks, Nichols said. On June 27, for example, Mercury will be below and to the right of the thin crescent moon, which may make it easier to find Mercury.

"You do have to set the alarm in order to do it," Nichols said, "but it's just a fun time to go see planets in the sky and learn what they look like."

Originally published on Live Science.  

The earliest evidence of mercury poisoning has been found in 5,000-year-old bones of humans buried in Spain and Portugal, according to a new study.

Exposure to the naturally occurring heavy metal may have toxic effects on the body including on the nervous, digestive and immune systems, according to The World Health Organization (WHO). That's why the WHO considers mercury one of the top 10 chemicals of "major health concern."

Today, people are most commonly exposed to some level of mercury when they eat certain fish or shellfish, though the levels are often low, according to the WHO. But how common was mercury exposure in the olden days?

Related: Shine On: Photos of dazzling mineral specimens

To figure this out, the researchers analyzed human bones collected from 23 different archaeological sites, which included pits and caves, across Spain and Portugal. The bones belonged to 370 individuals who lived in various time periods across a span of 5,000 years.

Analysis of some of the bones, mainly the humerus, the arm bone between the shoulder and the elbow, revealed unusually high levels of mercury, levels that would not have been caused by diet or by decomposition after death.

The researchers detected mercury levels of up to 400 parts per million in some of the remains, which is much higher than the 1 or 2 ppm that the WHO deems normal levels in human hair, according to a statement. 

The researchers say the unusually high levels of mercury were likely caused by exposure to cinnabar, a toxic mercury sulfide mineral that, when ground into a fine powder, has a bright red color and has been historically used to produce paint pigments, according to the statement. In fact, one of the largest cinnabar mines in the world is in Almadén, Spain. 

People started exploiting Almadén's cinnabar trove in the Neolithic period, around 7,000 years ago, according to the statement. The highest levels of mercury were in the remains that dated back to around 2900 B.C. to 2300 B.C., or the late Neolithic to the middle Copper Age (which was a transition between the Neolithic and Bronze Age). 

At this time, cinnabar had become a highly symbolic, probably sacred substance, "which was sought after, traded and extensively used in a variety of rituals and social practices," the authors wrote in the study, published Oct. 13 in the International Journal of Osteoarchaeology. 

In tombs dating back to this time period found in southern Portugal and Andalusia, cinnabar powder was used to paint chambers, decorate figurines and even spread over the dead. It's possible that people could have accidentally, or deliberately for reasons related to rituals, inhaled or consumed large amounts of mercury-filled cinnabar, according to the statement. 

By the end of the Copper Age and start of the Bronze Age, or around 2200 B.C., the use of cinnabar decreased significantly, according to the study.

Originally published on Live Science.

As climate change warms the Arctic, melting ice could release hazardous chemicals and radioactive material dating to the Cold War. Vanishing permafrost could also free viruses and bacteria that have slumbered beneath Arctic ice for tens of thousands of years, a new study shows.

By poring over historical records and past studies on contamination, the researchers found that in addition to fallout from nuclear explosions and pollutants such as mercury, arsenic and DDT, so-called Methuselah microorganisms — microbes that have been locked in permafrost for millennia — may awaken if climate change melts Arctic ice and the microbes defrost. That could release bacteria that are resistant to antibiotics, or introduce viruses that humans have never encountered before.

Related: Images of melt: Earth's vanishing ice

The term "permafrost" describes ground that has been continuously frozen for two years or longer and can include soil alone or dirt mixed with ice and covered by snow, according to the National Snow and Ice Data Center (NSIDC). Permafrost covers about 9 million square miles (23 million square kilometers) of the Northern Hemisphere, and it ranges in thickness from less than 3 feet (1 meter) to more than 3,000 feet (1,000 m), according to NSIDC.

Most Arctic permafrost cover has persisted for 800,000 to 1 million years, but climate change is eating away at even some of the most ancient ice reserves. Warming in the Arctic is progressing at least twice as rapidly as elsewhere in the world, and the past 15 years have warmed and melted the region to the point where the frozen landscape has been permanently transformed, according to the 2020 Arctic Report Card released by the National Oceanic and Atmospheric Administration (NOAA). 

One of the known hazards of Arctic warming is the release of vast reserves of greenhouse gases. Melting permafrost releases millions of tons of carbon dioxide and methane each year, and that amount is likely to increase as Earth continues to warm, Live Science reported in 2020.

But until now, scientists did not know the extent of hazards posed by pollutants stored in permafrost — "everything from microbes and potential viruses, to nuclear waste, chemicals and mercury," said lead study author Kimberley Miner, a science systems engineer with NASA's Jet Propulsion Lab at the California Institute of Technology (JPL-Caltech).

"Almost no one had ever put all of these different things together," Miner told Live Science.

What's in permafrost?

Scientists reviewed hundreds of prior studies "to catalogue emergent microbial, viral and chemical hazards within the new Arctic, and recommend research priorities to quantify and address these risks," the authors wrote.

Since nuclear testing began in the 1950s, radioactive materials have been dumped in the Arctic. During the Cold War, from the end of World War II until 1991, the United States and the Soviet Union conducted nuclear testing and research in the Arctic that left high levels of radioactive waste in soil and permafrost, the researchers discovered.

Detonations by the Soviet Union in the country's Novaya Zemlya archipelago, between 1959 and 1991, released 265 megatons of nuclear energy; the Russians also scuttled more than 100 decommissioned nuclear submarines in the Barents and Kara seas, releasing radioactive plutonium and cesium that can be detected today in sea bottom sediments and ice sheets, and in plants and soil beneath glaciers, according to the study.

The U.S. Camp Century, a nuclear-powered research center in Greenland, generated radioactive waste that was abandoned beneath the ice when the site was decommissioned in 1967. That ice is now rapidly retreating, with losses of about 268 tons (243 metric tons) per year, as the Arctic warms. And when a U.S. B-52 bomber crashed near Denmark's Thule Air Base in Greenland in 1968, its nuclear missile payload ruptured and released uranium and plutonium from four bombs into the ice sheet. Arctic radiation levels could remain harmful until 2500, the study authors reported.

Related: How radioactive is the human body?

Decades of mining in the Arctic across tens of thousands of square miles also left behind waste rich in toxic heavy metals such as mercury, arsenic and nickel. These pollutants have since sunk deep into Arctic soil and could threaten wildlife and human communities in Alaska, Canada, Greenland, Scandinavia and Russia, according to the study. An estimated 880,000 tons (800,000 metric tons) of mercury alone is stored in permafrost, and current warming trends could increase Arctic mercury emissions by up to 200% by 2300, the researchers found. 

Arctic permafrost also traps reservoirs of hazardous chemicals that were banned in the early 2000s, such as the insecticide DDT (dichloro-diphenyl-trichloroethane) and PCBs (polychlorinated biphenyls), a group of chemicals that were widely used in coolant fluids. These and other persistent organic pollutants, or POPs, traveled to the Arctic atmospherically and over time became concentrated in permafrost. However, "few studies have traced POP transport and risk," suggesting that "the impact of these chemicals within Arctic systems is underestimated," according to the study. 

Microbial threats could lurk in Arctic permafrost, too. Because Arctic microbes have evolved to survive subzero temperatures with minimal access to nutrients or water, many are capable of coming back to life even after thousands of years in a deep freeze. In prior studies, other researchers revived bacterial populations in permafrost dating to 30,000, 120,000 and even a million years ago, the scientists reported.

Finding the risk

But identifying pollutants in permafrost is just one part of calculating their risk to the Arctic and beyond; the other part of the equation is how quickly the permafrost is melting, Miner said.

"There's gradual thaw, which is just year-over-year thaw that moves down slowly from the top. And then there's abrupt thaw, where, for example, you can lose an entire side of a permafrost hill in a series of weeks. That's the kind of difference that will need to be mapped in order to understand when and how these things can emerge," Miner said.

Another important factor is that different pollutants pose varying levels of risk depending on pollutant quantity, duration of exposure, and how people and wildlife might come into contact with it, she added. For that reason, a next step for researchers could be assigning a risk profile to the recently identified pollutants in permafrost. But it's harder to evaluate the risks of permafrost's Methuselah microbes, as it's unknown which types of bacteria and viruses could emerge from ancient frozen soil.

"We have a very small understanding of what kind of extremophiles — microbes that live in lots of different conditions for a long time — have the potential to reemerge," Miner said. "These are microbes that have coevolved with things like giant sloths or mammoths, and we have no idea what they could do when released into our ecosystems."

In the long run, keeping these organisms and pollutants in their permafrost tombs would be preferable to trying to contain them once they've escaped, Miner said.

"It's absolutely critical to make sure that we do everything in our power to keep the permafrost — and generally the Arctic — frozen," she said. "It would be so much easier if we didn't have to deal with any of these, besides long-term remediation proposals."

The findings were published Sept. 30 in the journal Nature Climate Change.

Originally published on Live Science.

A newfound asteroid zips around the sun faster than any of its known kin.

The space rock, known as 2021 PH27, completes one lap around our star every 113 Earth days, its discoverers determined. That's the shortest orbital period of any known solar system object except the planet Mercury, which takes just 88 days to loop around the sun.

However, 2021 PH27 travels on a much more elliptical path than Mercury does and therefore gets considerably closer to the sun — about 12.4 million miles (20 million kilometers) at closest approach, compared to 29 million miles (47 million km) for the solar system's innermost planet. 

Related: The 7 strangest asteroids in the solar system

During those close solar passes, 2021 PH27's surface gets hot enough to melt lead — about 900 degrees Fahrenheit (500 degrees Celsius), the discovery team estimates. Those deep dips into the sun's gravity well also mean the asteroid experiences the largest general relativity effects of any known solar system object. Such effects manifest as a slight wobble in 2021 PH27's elliptical orbit around the sun, which the team has observed.

That orbit, by the way, is not stable over the long haul. 2021 PH27 will likely collide with the sun, Mercury or Venus a few million years from now, if it's not ejected from its current path by a gravitational interaction first, team members said.

2021 PH27 was first spotted on Aug. 13 by astronomers using the Dark Energy Camera (DEC), a powerful multipurpose instrument mounted on the Víctor M. Blanco 4-meter Telescope at the Cerro Tololo Inter-American Observatory in Chile. 

The team was able to pin down the asteroid's orbit over the next few days, thanks to further observations by the DEC and the Magellan Telescopes at the Las Campanas Observatory in Chile, as well as smaller scopes in Chile and South Africa operated by the Las Cumbres Observatory. 

The 2021 PH27 push postponed some scheduled observations with those instruments, but the reshuffling was worth it, team members said.

"Though telescope time for astronomers is very precious, the international nature and love of the unknown make astronomers very willing to override their own science and observations to follow up new, interesting discoveries like this," discovery team leader Scott Sheppard, an astronomer at the Carnegie Institution for Science in Washington, D.C., said in a statement.

Sheppard and his colleagues estimate that 2021 PH27 is about 0.6 miles (1 km) wide. The space rock may have originated in the main asteroid belt between Mars and Jupiter, then gotten kicked inward by gravitational interactions with one or more planets, the researchers say. 

However, 2021 PH27's orbital path is tilted by 32 degrees relative to the plane of the solar system. Such a high inclination suggests it might instead be an extinct comet that was born in the far outer solar system, then captured into a closer orbit after passing by Mars, Earth or another rocky planet.

Further observations could help resolve this mystery, but Sheppard and other astronomers will have to wait a few months to collect more data. 2021 PH27 is now moving behind the sun from our point of view, and it won't re-emerge until early 2022, discovery team members said.

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. 

When Amazon founder Jeff Bezos offered her a seat on the first crewed flight of his space tourism enterprise Blue Origin, it was an invitation aviator Wally Funk had waited six decades to receive.

Funk, age 82, is one of a dozen women who have come to be known as the Mercury 13 in pointed contrast to NASA's original astronauts, the Mercury 7. Funk and the others were skilled pilots who, like their male counterparts, dreamed of flying even higher, to space. But they were never included in NASA's vision for spaceflight and never became astronauts — until now. 

"Wally Funk has really never given up on her dream of spaceflight," Margaret Weitekamp, curator of the Smithsonian's National Air and Space Museum's space history department who wrote a book about the women who lobbied to be included in NASA's astronaut program, told Space.com. "There's a nice bit of poetic justice in including her on this flight."

Related: How to watch Blue Origin launch Jeff Bezos into space on July 20
Live updates: Blue Origin's first astronaut launch updates

Fighting for access to space 

Funk and Bezos will make up half the crew of the first crewed flight of Blue Origin's reusable suborbital space tourism vehicle, dubbed New Shepard, when it launches from the west Texas desert on Tuesday morning (July 20). She'll become the oldest person to fly in space when she launches.

But Funk laid the groundwork for this flight during a brief period six decades ago, when she became one of the group that was, decades later, dubbed the Mercury 13 and is often misleadingly portrayed as a sort of women's counterpart for NASA's first group of astronauts, although the agency never endorsed their efforts and only began recruiting women for spaceflight in 1978.

"It was never a NASA project, it was really a privately funded investigation into women's physical capabilities for spaceflight," Weitekamp said. Funk, already an accomplished pilot in her early 20s, learned about the project in 1960 when she read about Jerrie Cobb, a female pilot who volunteered to undergo tests meant to determine whether a human body could withstand the strain of spaceflight.

Related: As space billionaires take flight, 'the right stuff' for space travel enters a new era

Those tests were developed for NASA by a team led by William Randolph Lovelace and were designed to identify any weaknesses that might identify hidden health issues before flight. NASA used the tests to evaluate the military test pilots it had recruited for the young human spaceflight program.

But where the agency was focused on reaching milestones in space exploration, Lovelace had a bigger picture in mind, an ideal pulled from science fiction of whole offices lofted from 1950s America into orbit. Just as women were the secretaries and telephone operators on Earth, so too they would be in space, this line of thinking went, according to Weitekamp.

Independently of his NASA work, then, Lovelace was interested in how women's bodies fared during these tests, which spanned a week. The tests included everything from a tilt table and a stint in a sensory deprivation chamber to examining the women's stomach acids.

Related: Blue Origin's launch with Jeff Bezos: Everything you need to know

Funk went into them with a competitive streak.

"Her aim was to not only to just do it to the best of her ability, every test, but to try to do better than whoever had gone before her," Sue Nelson, a science journalist who later traveled with Funk to research her book, "Wally Funk’s Race for Space" (Chicago Review Press, 2019), told Space.com. "She just is immensely driven and competitive, which is a sort of the typical early astronaut, test pilot type really — she fits the mold of those early astronauts."

And Funk and 12 other women were deemed to have passed Lovelace's tests. "The 13 of the 25 who became the finalists on average did as well or in some cases better than the Mercury 7 astronauts did," Weitekamp said. (Some of the tests focused on cardiovascular health, where the women had a key advantage, she noted, since most of the Mercury 7 smoked.)

Lovelace wanted to bring those 13 in for still more tests, this time at government facilities, but couldn't get approval. And while some, like Funk, applied directly to NASA, it didn't make a difference.

"I got a hold of NASA, four times, I said, 'I want to become an astronaut.' But nobody would take me," Funk said in the video released to announce her flight. "I didn't think that I would ever get to go up."

Related: Meet the crew launching on Blue Origin's 1st astronaut flight on July 20

Unlike the close-knit men of the Mercury program, Funk hadn't met most of the other participants, since the women had undergone the initial tests in ones and twos. And, of course, whereas the Mercury 7 became celebrities and spent the bulk of their careers with NASA, the women found other ways to fill their time.

"It was a very short part of their lives," Nelson said. "Wally just kept on with her career and doing loads of interesting things."

For Funk, with no spaceflight on the horizon, she set about traveling on Earth instead for a few years, then building a career as a pilot, flight teacher, and eventually investigating plane crashes and other safety issues for the government. In the video released with Blue Origin about her joining the flight, she said that she has racked up 19,600 flight hours on a variety of aircraft and has taught more than 3,000 people to fly.

NASA eventually came around on flying women, too late for Funk and the others. Sally Ride became the first American woman in space in 1983, although it wasn't until 1995 that NASA made Eileen Collins the first female pilot of the space shuttle. (Collins invited Funk and others who underwent Lovelace's tests to watch the launch.)

"Like so many things that we see in women's history, the advancement happens in fits and starts," Weitekamp said. "There's some interest and then it doesn't necessarily have a direct legacy."

Related: From Yuri Gagarin's launch to today, human spaceflight has always been political

Opportunity 60 years later 

Blue Origin has long showed an interest in nodding to spaceflight's history, so it's not a coincidence that Funk will step inside the New Shepard capsule on its first crewed flight. (The vehicle itself, of course, is dubbed for one of the group she so notably did not become, Alan Shepard, who became the first American in space with a suborbital flight on May 5, 1961.)

For Nelson, seeing Bezos' announcement was a poignant moment. "It's poignant, she has waited a lifetime for this," she said. "I just got a lump in my throat and tears welled up." And while Funk has long held a ticket with Blue Origin competitor Virgin Galactic, Nelson said, the New Shepard model represents a different vision of spaceflight.

"It's so much more akin in my eyes as a sort of old-fashioned astronaut experience, more similar to the one that if NASA had allowed women into the astronaut corps 20 years earlier," Nelson said.

And from Nelson's description of calling to congratulate her friend on the invitation, Funk is conscious of the weight of history that she'll carry into the capsule.

"She said, 'I've waited a lifetime, honey,' and then she said, 'I'm going up for all of us.'"

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

The Peruvian Amazon glitters like gold in a gorgeous new photo taken aboard the International Space Station.

While that glow is just sunlight reflecting off hundreds of pits of muddy water, there is plenty of gold in them thar hills. Each glistening pool is a gold-prospecting pit, according to NASA's Earth Observatory website, likely dug by independent miners looking to unearth some of the Amazon's ancient treasures.

"Each pit is surrounded by de-vegetated areas of muddy soil," Justin Wilkinson, a grant specialist at Texas State University, wrote for Earth Observatory. "These deforested tracts follow the courses of ancient rivers that deposited sediments, including gold."

Peru's Madre de Dios state, shown in this picture, is home to one of the largest independent gold mining industries on Earth, Wilkinson wrote. As many as 30,000 small-scale miners (working outside of government regulations) prospect illegally in the area, tearing up the rainforest with excavators and dump trucks in order to unearth the gold underneath.

Illegal mining can be a boon to impoverished workers in Madre de Dios, but a detriment to the Amazon; according to a 2011 study in the journal PLOS One, gold mining is the single greatest cause of deforestation in the region.

These unregulated operations also pose a risk to local communities. Miners mix sediments with boiled mercury in order to separate gold from other minerals, according to Nature.com. As a result, up to 55 tons (50 metric tons) of mercury end up in rivers or the atmosphere every year. Locals who eat a lot of fish from these polluted rivers are more than three times as likely to have mercury poisoning than non-fish-eaters, a 2012 PLOS One study found.

But from space, these harsh realities blur out of focus. For the astronaut who took this photo on Dec. 24, 2020, the world far below was just a river of gold.

Originally published on Live Science.

Just weeks after Jupiter and Saturn dazzled stargazers by canoodling side-by-side in the night sky, another "great conjunction" of planets is on the way — and this time, Mercury is invited to the party, too.

On Sunday (Jan. 10), the three planets will appear close together in a rare triple conjunction event. According to Live Science's sister site Space.com, the three bodies will form a "small, neat triangle" low in the west-southwest sky, appearing about 30 to 45 minutes after sunset that evening. Jupiter will appear at the top of the triangle, glowing about two-and-a-half times brighter than Mercury, and 10 times brighter than Saturn.

Because the trio will appear so close to the horizon and so close to sunset, Space.com's skywatching columnist Joe Rao strongly recommends that stargazers use a pair of binoculars to clearly see the planets against the twilight sky.

Related: The 12 strangest objects in the universe

This may be the last chance to catch Jupiter and Saturn in the evening sky for a while, as the planets continue to descend farther and farther into the blazing sunset. (Mercury, meanwhile, will continue to rise, remaining visible through the end of the month. Space.com has more details on how to view it.)

Though the three planets seem to be bumping elbows, they are still taking social-distancing guidelines to the extreme. When the conjunction began a few weeks ago, Jupiter was about 550 million miles (890 million kilometers) from Earth, or about 5.9 times the distance between Earth and the sun, while Saturn was about 1 billion miles (1.6 billion km) from Earth, or about 10.8 times Earth's distance from the sun. Mercury, meanwhile, remains millions of miles closer, at about 120 million miles (195 million km) from Earth.

The three planets merely look close together because their orbits put them all in a straight line, relative to Earth.

Originally published on Live Science.

A spacecraft bound for Mercury beamed home stunning views of Earth during a crucial flyby conducted early today (April 10).

BepiColombo, a joint mission conducted by the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA), is headed to our solar system's innermost planet. But to reach that destination, the spacecraft, which launched in October 2018, needs to conduct a complex sequence of nine different planetary flybys.

Related: Farewell, Earth! BepiColombo makes successful Earth flyby

The first of those passes was close to home, as today (April 10), BepiColombo came within 7,877 miles (12,677 kilometers) of Earth.

Fortunately, the spacecraft was well prepared to make the most of the opportunity since, in addition to its more technical scientific instruments, BepiColombo carries three different cameras. Mission personnel are still processing many of the images snapped by the spacecraft, but ESA and JAXA have released both individual images and animated series produced as BepiColombo headed toward Earth. 

The cameras are set up to take "selfies," so all the new images show both Earth and bits and pieces of the spacecraft itself. That "spacecraft" is a bit of a misnomer: although BepiColombo is currently traveling as one unit, it consists of three separate units: JAXA's Mercury Magnetospheric Orbiter, ESA's Mercury Planetary Orbiter and ESA's Mercury Transfer Module, which is ferrying the two scientific probes to their destination.

The flyby was also humans' last chance to spot the spacecraft directly: from now on, ESA and JAXA will be relying on communications only. But skywatchers armed with good binoculars or a small telescope, depending on their location and the weather, had the opportunity to wave goodbye to BepiColombo as a bright dot streaking across the sky.

When BepiColombo arrives at Mercury for flybys beginning in 2021 and begins orbital science operations in 2026, it will be humanity's first delegate to the tiny world since 2015, when NASA's Messenger spacecraft purposely crashed into the planet's surface to end its mission. 

•  Photos of Mercury from NASA's Messenger spacecraft 
•  BepiColombo in pictures: A Mercury mission by Europe and Japan 
•  What’s the closest planet to Earth? Not Venus, scientists say 

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

Could Mercury's close orbit around the sun help the planet generate ice?

It sounds like a paradox, but new analysis of the planet's surface chemistry suggests that heat-generated ice may indeed be the case.

Even though daytime temperatures on Mercury soar to 750 degrees Fahrenheit (400 degrees Celsius), ice can occur in craters sheltered from the sun. There, the surface is exposed to cold space at about minus 330 F (minus 200 C).

Video: Ice on Mercury – How does it form?
Related: Photos of Mercury from NASA's Messenger spacecraft

We've known about this ice for almost a decade thanks to observations from NASA's now-defunct MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) spacecraft. But the explanation for how some of the ice got there, chemically speaking, remains under investigation. A new study shows how water can collect on the surface even amid these extremely hot temperatures.

"This is not some strange, out-of-left-field idea. The basic chemical mechanism has been observed dozens of times in studies since the late 1960s," Brant Jones, a researcher in Georgia Tech's School of Chemistry and Biochemistry and the lead author of the new study, said in a statement. "But that was on well-defined surfaces. Applying that chemistry to complicated surfaces like those on a planet is groundbreaking research."

The minerals on Mercury's surface contain groups of bonded oxygen and hydrogen atoms known as hydroxyls. Protons from the solar wind (the constant stream of charged particles from the sun) are common on the planet's surface, since there is not enough of a magnetic field to repel the particles. 

This study's model suggests that the magnetic field can cause protons (positively charged subatomic particles) to migrate across Mercury, so the protons can then implant themselves in the soil and the hydroxyl groups. The sun's searing heat energizes the hydroxyl groups, causing them to crash into each other. These collisions create water (which is also made from hydrogen and oxygen, just in different proportions), as well as freeing up extra hydrogen that leaves the surface and drifts above Mercury.

As for the water molecules, some of them get broken down by sunlight and dissolve into their elemental components. Other water molecules escape from the surface and fly into space. However, a few water molecules escape these fates and instead land on the poles of Mercury, making it into permanently shadowed craters. 

And there, the molecules can stay, since Mercury has no substantial atmosphere that would further affect the water molecules by conducting heat, for example. While this sounds like a subtle process, over time, the water ice would add up. 

The model suggests that in 3 million years, Mercury would accumulate 11 trillion tons (nearly 10 trillion metric tons) of water ice, which is roughly 10% of the observed ice on the planet. Other ice may have arrived from small worlds such as asteroids, comets and meteorites.

"It's a little like the song 'Hotel California.' The water molecules can check in to the shadows, but they can never leave," study principal investigator Thomas Orlando, who studies electron- and proton-induced surface chemistry at Georgia Tech, said in the statement. 

Mercury is not alone in having ice on its surface, as water ice has also been discovered on the moon and on small worlds such as asteroids and comets. These locations may have variations in water deposition, however. "The process in our model would not be anywhere near as productive on the moon. For one, there's not enough heat to significantly activate the chemistry," Jones said.

A study based on the research was published Monday (March 16) in The Astrophysical Journal Letters.

• Scorching-hot Mercury has a surprisingly icy north pole
• Water ice on Mercury: How it stays frozen (infographic)
• What’s the closest planet to Earth? Not Venus, scientists say 

Follow Elizabeth Howell on Twitter @howellspace. Follow us on Twitter @Spacedotcom and on Facebook. 

The tiny planet Mercury scooted across the sun's face today (Nov. 11) for the last time until 2032, and skywatchers around the world had the chance to witness the rare celestial event. 

During this 2019 transit of Mercury, the innermost planet spent about 5.5 hours crossing in front of the sun from our perspective on Earth. Skywatchers across the Americas, Africa and Europe could see at least part of Mercury's journey across the sun, but only with telescopes or high-power binoculars equipped with protective solar filters. Meanwhile, several spacecraft, including NASA's Solar Dynamics Observatory, provided views of the event from space. 

Mercury's silhouette began to encroach on the sun's disk at 7:35 a.m. EST (1235 GMT), when the sun was above the horizon for viewers in South America, eastern Central America and the U.S. East Coast. In the rest of the U.S., Mercury was already making its way across the sun by sunrise. In most of Africa and Europe, Mercury was still crossing the sun as the sun dipped below the western horizon. 

Related: The Mercury Transit of 2019 in Photos! The Best Views Until 2032
More: Here's Why Mercury Transits Are So Rare

Mercury transit from Earth and space

While people on the ground carefully examined the sun and shared videos and photos on Twitter, astronomers shared their view of the action through sun-gazing telescopes. Technicians with NASA’s Solar Dynamics Observatory posted near real-time imagery and video of the Mercury transit in ultraviolet and visible wavelengths. Meanwhile, the European Space Agency’s Proba-2 mission was snapping images as well, according to an ESA tweet, although those photos haven't been released yet.

As of the final minutes of the transit, there was no word on whether the six astronauts on board the International Space Station would try to catch a glimpse of the transit. The Expedition 61 crew is equipped with astronomical observing equipment as well as cameras to catch celestial events, and they did gather footage during the 2017 solar eclipse.

On Twitter and in interviews, NASA and ESA used the opportunity to highlight current and upcoming missions to examine exoplanets and Mercury itself. NASA heliophysicist Alex Young told Space.com that the Mercury transit is similar to how the Transiting Exoplanet Survey Satellite (TESS) searches for exoplanets, as they travel across their parent stars.

ESA highlighted three of its missions on Twitter: BepiColombo en route to Mercury, the ESA Solar Orbiter that is getting ready for launch in 2020 to study the sun, and the Characterising Exoplanet Satellite (CHEOPS) that will also search for exoplanets using the transit method after its launch in December.

Transits of Mercury are relatively rare events, with about 13 happening every century, on average. The last Mercury transit was on May 9, 2016, and the next one will be on Nov. 13, 2032. Skywatchers in the U.S. won't get another Mercury transit until May 7, 2049. 

How Mercury transits occur

Mercury and Venus are the only two planets that can transit the sun from Earth's perspective, because they are the only planets whose orbits are closer to the sun than Earth's. Venus last passed before the sun on June 6, 2012, and the next Venus transit isn't until Dec. 11, 2117. These transits happen because the planets' orbits are slightly tilted to the ecliptic, or the plane of Earth's orbit, and those orbits intersect at two places called "nodes." Transits occur when Earth crosses a node at the same time as the other planet. In Mercury's case, this always happens in May or November. For Venus, transits occur in June and December. 

Amateur astronomers and astrophotographers around the world took heed of today's rare celestial treat and (weather permitting) captured some incredible images of Mercury as it inched across the sun like a tiny, traveling ink blot. With an apparent diameter of 10 arc seconds, Mercury's width was about 0.5% that of the sun. In terms of area, the tiny planet covered only 0.003% of the sun's disk. To see the little fleck on the sun, observers had to use magnifying equipment with special solar filters; it was too small to see with solar eclipse glasses. 

Though the Mercury transit was not visible everywhere in the world — like Asia, Australia and Alaska, where it happened at night — anyone with an internet connection could still follow the event live online, thanks to astronomy webcast services like Slooh and the Virtual Telescope Project. NASA's Solar Dynamics Observatory also provided near-real-time views of the sun from space. These telescopes offered some solace to viewers across the midwestern and northeastern U.S., where overcast skies made it difficult for many eager transit-watchers to get a good view of the sun. 

While skywatchers across the globe celebrated the rare chance to see a Mercury transit today, scientists also took the opportunity to learn more about the innermost planet — particularly its thin atmosphere. When Mercury passes in front of the sun, scientists can observe changes in sunlight that passes through its tenuous atmosphere, allowing them to study its elemental composition. 

Waiting for 2032

It will be 13 years before Mercury transits the sun again and 30 years until it happens again in the U.S. — but if you got special gear to watch this transit safely, don't ditch those solar filters just yet! You can use the same solar filtered-telescopes and binoculars to watch some solar eclipses before the next transit, so long as the filters are not damaged.

Solar eclipses, when the moon blocks at least a portion of the sun's disk, occur about two to five times per year, with total solar eclipses — when the moon completely blocks the sun from view — occurring about once every 18 months, on average. To find out when the next solar eclipse will be visible near you, check out this handy list of eclipses with interactive maps from timeanddate.com. 

Editor's note: If you captured an amazing photo of the Mercury transit, or any other celestial sight, and you'd like to share it with us and our partners for a story or image gallery, send images and comments in to Editor-in-Chief Tariq Malik at spacephotos@space.com.

• Mercury Transit 2019: The Astronomical History of This Rare Celestial Event
• Venus Crosses the Sun for Last Time Until 2117, Skywatchers Rejoice
• How to Catch the Next Eclipse: A List of Solar and Lunar Eclipses in 2020 and Beyond

Email Hanneke Weitering at hweitering@space.com or follow her @hannekescience. Follow Elizabeth Howell on Twitter @howellspace. Follow us on Twitter @Spacedotcom and on Facebook.

Our cosmic neighbor Mercury is the runt of the solar system; it's not much bigger than Earth's moon and is so hard to spot that it's known as "the elusive planet." But we're about to get a rare and spectacular view of the tiny world as it sails across the sun in an event known as a transit.

On Monday (Nov. 11), Mercury will pass between Earth and the sun. Because the planet is so tiny and so close to the sun, it doesn't block the sun's light, as the moon does during an eclipse. Rather, Mercury will be visible from Earth as a wee dot silhouetted against a vast, glowing, solar backdrop, according to NASA.

Here on Earth, we'll be able to watch that black speck move slowly across the sun, a sight that appears only 13 times in a century. And if you miss this year's Mercury transit, you'll have to wait until 2032 to catch one.

Related: Gorgeous New Mercury Maps Showcase Planet's Striking Features

The show begins at 7:36 a.m. EST on the eastern coast of the U.S. and will already be underway when the sun rises west of the Rocky Mountains. Mercury will travel halfway across the sun by around 11:20 a.m. EST. From start to finish, the transit will last about 5.5 hours, finishing at 1:04 p.m. EST according to NASA. 

If skies are clear, the transit will be visible from most of North America; parts of Europe, Asia and Antarctica; and all of South America and Africa, Live Science sister site Space.com reported.

Spotting the tiny, swiftly moving planet requires a telescope or binoculars. However, any viewing device that points directly at the sun must be fitted with protective solar filters to prevent serious eye damage. Disposable eclipse glasses should never be used with binoculars and telescopes; magnifying lenses increase sunlight's destructive power and can melt eclipse glasses' flimsy filters, as demonstrated in a video shared to YouTube in 2017 by journalist and photographer Vince Patton.

The last Mercury transit took place in 2016, and NASA's Solar Dynamics Observatory (SDO) captured unprecedented images of the event, at a higher resolution than ever before. But the transit isn't just an awe-inspiring spectacle; it has scientific importance, too. When Mercury is positioned directly in front of the sun for hours at a stretch, researchers are able to study the planet's exosphere, a very thin atmosphere of gases, to determine their distribution and density, NASA scientist Rosemary Killen said in a statement.

"Sodium in the exosphere absorbs and reemits a yellow-orange color from sunlight, and by measuring that absorption, we can learn about the density of gas there," Killen said.

To find out more about Monday's Mercury transit and where you can watch it, including live webcast views on the day of the transit, visit Space.com.

• 11 Fascinating Facts About Our Milky Way Galaxy
• 10 Strange Facts About Mercury (A Photo Tour)
• 10 Solar Eclipses That Changed Science

Originally published on Live Science.

Mercury will pass across the face of the sun Monday (Nov. 11) in its first such "transit" since 2016.

The Mercury transit — which begins Monday at 7:35 a.m. EST (1235 GMT) and ends at 1:02 p.m. EST (1804 GMT) — is accessible to amateur astronomers, as long as they have the right equipment to view the event safely. (Warning: Never look directly at the sun without protection; serious and permanent eye damage can result.)

Here's a brief rundown of the ways you can safely watch the transit, either first-hand or live online.

Related: Mercury Transit 2019: Where and How to See It on Nov. 11

Projecting the image

Mercury is so small that projecting the image using a simple pinhole camera, as many observers do to view solar eclipses, will not produce good results; it's likely you won't be able to see anything at all. Instead, you can project the image using binoculars, refractors or small Newtonian telescopes. (Schmidt-Cassegrain and Maksutov designs can't be used for this, because of the risk of damage.)

Put a low-power eyepiece into your telescope — one that you don't mind losing if the sun's heat cracks it. Do not look through the eyepiece or the finder scope. Instead, align the telescope using its shadow on the ground. The more closely aligned the scope is to the sun, the darker and more circular its shadow will appear, according to the British Astronomical Association (BAA).

Take a piece of white paper and hold it about 1 foot (30 centimeters) away from the eyepiece to see the image. You may need to wiggle the telescope a bit to get a good view.

Binoculars or telescopes

You can also outfit your binoculars or telescope with solar filters to view the transit. The type of solar filter depends on your equipment, so check with the manufacturer to see what's approved.

Alternatively, you can make your own filters using a sheet of Mylar or Baader AstroSolar Film. Just be sure that the homemade filter is securely over the front end of your binoculars or telescope, with no cracks.

"It is essential that the filter fixes very securely to your telescope, that it is undamaged, and that it is designed for safe use with your telescope," the BAA officials wrote in a press release. "Only buy from reputable suppliers you trust, and thoroughly inspect your filters for damage every time you use them."

Filters designed for eyepieces should never be used because they are "of suspect quality" and often crack when exposed to the sun's heat, the BAA added.

Community telescopes

Many museums or amateur astronomy organizations are holding special public events for the Mercury transit. So if you don't have your own gear, check the nearest science museum or astronomy club to see if they are going to set something up somewhere in your community.

You can find the nearest astronomy club in your area here. 

Watching online

Another option is to watch the transit from wherever you happen to be that day, which is especially handy if you are stuck at work or school. Space.com will show live webcasts from Slooh and the Virtual Telescope Project. 

The Slooh online observatory will begin streaming live views of the Mercury transit from telescopes around the world at 7:30 a.m. EST (1230 GMT). You can watch it live here on Space.com or directly via Slooh's YouTube channel. 

At the same time, astrophysicist Gianluca Masi of the Virtual Telescope Project in Italy will also stream live telescope views of the transit. You can watch the free webcast live here.

Meanwhile, NASA will post real-time images from its Solar Dynamics Observatory at mercurytransit.gsfc.nasa.gov/2019. 

Editor's note: Visit Space.com on Monday to see live webcast views of the rare Mercury transit from Earth and space, and for complete coverage of the celestial event. If you SAFELY capture a photo of the transit of Mercury and would like to share it with Space.com and our news partners for a story or gallery, you can send images and comments in to managing editor Tariq Malik at spacephotos@space.com. 

• Mercury Transit 2019: Here's Why This Celestial Event Is So Rare
• The Mercury Transit of 2016 in Amazing Photos
• How to Safely Observe the Sun (Infographic)

This article was originally posted on May 6, 2016 for the previous Mercury transit and has been updated for 2019.

Follow Elizabeth Howell @howellspace. Follow Space.com on Twitter @Spacedotcom and on Facebook.

A California woman is in a semi-comatose state after using an imported anti-wrinkle cream that was tainted with mercury, according to news reports

The 47-year-old woman first went to the emergency room back in July after experiencing slurred speech, numbness in her hands and face and trouble walking, according to local news outlet KCRA. 

After testing some of the woman's cosmetic products, officials found that one of her skin creams contained high levels of methylmercury, a particularly toxic form of mercury. This is the first known case of methylmercury poisoning linked to a skin cream in the United States, according to the Sacramento County Department of Health Services.

The cream, known as Pond's Rejuveness, was sold in Mexico, and the woman bought it through an informal network of friends. The mercury was added by a third party, and not the Pond's manufacturer, officials said.

Methylmercury can form when bacteria react with the metal mercury in water, soil or plants, according to the National Institutes of Health. Fish and shellfish are the most common sources of methylmercury exposure in the U.S., according to the Environmental Protection Agency.

It's unclear if the methylmercury in the woman's skin cream got there by mistake, or if someone purposely added it. However, it's known that mercury can stop the production of the skin pigment melanin, and so it could lighten skin and remove age spots, KCRA reported.

People may normally have small amounts of mercury in their blood, up to 5 micrograms per liter; but the woman's level was sky high, at more than 2,600 mg/L, according to the local news station.

The woman's condition worsened since her hospitalization and she has stopped responding to verbal commands. 

Public health officials are warning the public to stop using similar skin creams imported from Mexico. 

•  27 Oddest Medical Case Reports 
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Originally published on Live Science. 

The year goes by quickly for this newfound asteroid. The so-called 2019 LF6 asteroid circles the sun every 151 days, the shortest orbit of any known asteroid.

This swift-moving rock snuggles closer to the sun than does our planet, which takes 365 days to make the solar trek. LF6 is one of 20 others, collectively called Atira asteroids, that move within a cosmic hug of our planet, according to a statement from the California Institute of Technology.

Although this meteor is quite large — around 0.6 miles (1 kilometer) across — it had remained hidden from astronomers' prying eyes until now. "LF6 is very unusual both in orbit and in size — its unique orbit explains why such a large asteroid eluded several decades of careful searches," Quanzhi Ye, a postdoctoral student at Caltech, said in the statement.

The asteroid's elliptical orbit brings the space rock well outside of the plane on which the planets of our solar system orbit, and it gets closer than Mercury does to the sun. (Mercury is the sun's nearest planetary neighbor.) This asteroid could have been slingshot out of the plane when it came too close to the gravitational disturbances of Venus or Mercury, according to the statement. [10 Interesting Places in the Solar System We'd Like to Visit]

Ye discovered the chunk of rock using Palomar Observatory's Zwicky Transient Facility (ZTF), a camera that rapidly scans the night sky searching for signals from exploding or flashing stars and moving asteroids.

But Ye and his team have a short window every night to detect these objects. Because they're so close to the sun, the best time to find them is around 20 to 30 minutes before sunrise or after sunset.

Previously, the same team, in collaboration with others as part of an observing campaign called Twilight, discovered another asteroid using this system. That asteroid also turned out to orbit the sun outside of the solar system's plane. Called 2019 AQ3, that space rock circled the sun every 165 days and held the title for shortest asteroid year, until now.

Finding an asteroid this large is quite rare. "You don't find kilometer-size asteroids very often these days," Ye said. "Thirty years ago, people started organizing methodical asteroid searches, finding larger objects first, but now that most of them have been found, the bigger ones are rare birds."

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Originally published on Live Science.