One of a dozen new moons discovered around Jupiter is circling the planet on a suicide orbit that will inevitably lead to its violent destruction, astronomers say.

Researchers in the US stumbled upon the new moons while hunting for a mysterious ninth planet that is postulated to lurk far beyond the orbit of Neptune, the most distant planet in the solar system.



The team first glimpsed the moons in March last year from the Cerro Tololo Inter-American Observatory in Chile, but needed more than a year to confirm that the bodies were locked in orbit around the gas giant. “It was a long process,” said Scott Sheppard, who led the effort at the Carnegie Institution for Science in Washington DC.



Jupiter, the largest planet in the solar system, was hardly short of moons before the latest findings. The fresh haul of natural satellites brings the total number of Jovian moons to 79, more than are known to circle any other planet in our cosmic neighbourhood.



Nine of the new moons belong to an outer group that orbit Jupiter in retrograde, meaning they travel in the opposite direction to the planet’s spin. They are thought to be the remnants of larger parent bodies that were broken apart in collisions with asteroids, comets and other moons. Each takes about two years to circle the planet.



Two more of the moons are in a group that circle much closer to the planet in prograde orbits which travel in the same direction as Jupiter’s spin. Most likely to be pieces of a once larger moon that was broken up in orbit, they take nearly a year to complete a lap around Jupiter. Which direction the moons swing around the planet depends on how they were first captured by Jupiter’s gravitational field.

Astronomers describe the twelfth new Jovian moon as an “oddball”. Less than a kilometre wide, the tiny body circles Jupiter on a prograde orbit but at a distance that means it crosses the path of other moons hurtling towards it. Scientists have named the new moon Valetudo after the Roman god Jupiter’s great-granddaughter, the goddess of health and hygiene. But given the impending violence, it may be more than coincidence that Vale Tudo, which translates from Portuguese as “anything goes”, is an early form of full-contact mixed martial arts. 



“Valetudo is like driving down the highway on the wrong side of the road,” said Sheppard. “It is moving prograde while all the other objects at a similar distance from Jupiter are moving retrograde. Thus head-on collisions are likely.”



Sheppard, whose report appears in the International Astronomical Union Minor Planet Electronic Circular, suspects that Valetudo is the final remnant of a once much larger moon that has been ground to dust by collisions in the past.

Which raises the question of how long the tiny moon has left. “Collisions don’t happen all that frequently, every billion years or so,” said Sheppard. “If one did happen, we would be able to detect it from Earth, but it is unlikely to happen anytime soon.” </s> Ten new moons—including one ‘oddball’—discovered around Jupiter

Jupiter’s orbital family has just rapidly expanded, with scientists today announcing the discovery of 10 new miniature moons around the gas giant. That brings its total known satellites to 79, the most in the solar system.

The new moons, pictured as circles above, were discovered last year by a team of astronomers. After verification, they are being reported today by the International Astronomical Union, based in Paris. At the time, the researchers were searching for a theorized massive planet far beyond Pluto, known as Planet X or Planet Nine, which is thought to be tugging on the orbits of distant solar system objects. Although the scientists’ planet hunt has so far come up dry, the team, using the recently upgraded Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory in Chile, also had Jupiter in view, leading to the discovery. Additional observations over a year confirmed the orbits of the moons, all of which are 3 kilometers or less in diameter.

The moonlets mostly follow Jupiter’s known patterns: Located far beyond the planet’s large primary moons (purple), two of the new moonlets belong to a grouping (blue) that spins in the same direction as the planet, all of which are believed to be the fragments of one large shattered moon. Seven fall in a farther out “retrograde” cluster (red) rotating against the planet’s spin, their opposing path kick-started when ancient moons collided with comets, asteroids, or other moons.

But one moon, tentatively dubbed “Valetudo” (green), is an oddball, orbiting with Jupiter’s spin but within the retrograde cluster. The satellite, named for Jupiter’s great-granddaughter, could be a bit of unfinished business, the last remnant of the ancient moons that provided the grist for the retrograde cluster, the team theorizes. Its path weaving within the retrograde moons is unstable, they add; a collision, at some point, is likely.

*Correction, 17 July, 10:30 a.m: An earlier version of this article misstated the number of new moons discovered. Although the team did discover 12 new moons, two were announced last year. </s> Astronomers are still finding moons at Jupiter, 400 years after Galileo used his spyglass to spot the first ones.

NEW YORK — Astronomers are still finding moons at Jupiter, 400 years after Galileo used his spyglass to spot the first ones.

The latest discovery of a dozen small moons brings the total to 79, the most of any planet in our solar system.

Scientists were looking for objects on the fringes of the solar system last year when they pointed their telescopes close to Jupiter’s backyard, according to Scott Sheppard of the Carnegie Institute for Science in Washington. They saw a new group of objects moving around the giant gas planet but didn’t know whether they were moons or asteroids passing near Jupiter.

“There was no eureka moment,” said Sheppard, who led the team of astronomers. “It took a year to figure out what these objects were.”

They all turned out to be moons of Jupiter. The confirmation of 10 was announced Tuesday. Two were confirmed earlier.

The moons had not been spotted before because they are tiny. They are about one to two miles across, said astronomer Gareth Williams of the International Astronomical Union’s Minor Planet Center.

And he thinks Jupiter might have even more moons just as small waiting to be found.

“We just haven’t observed them enough,” said Williams, who helped confirm the moons’ orbits.

The team is calling one of the new moons an ‘oddball’ because of its unusual orbit. Sheppard’s girlfriend came up with a name for it: Valetudo, the great-granddaughter of the Roman god Jupiter.

Valetudo is in Jupiter’s distant, outer swarm of moons that circles in the opposite direction of the planet’s rotation. Yet it’s orbiting in the same direction as the planet, against the swarm’s traffic.

“This moon is going down the highway the wrong way,” Sheppard said.

Scientists believe moons like Valetudo and its siblings appeared soon after Jupiter formed. The planet must have acted like a vacuum, sucking up all the material that was around it. Some of that debris was captured as moons.

“What astonishes me about these moons is that they’re the remnants of what the planet formed from,” he said.

Telescopes in Chile, Hawaii and Arizona were used for the latest discovery and confirmation.

Galileo detected Jupiter’s four largest moons, Io, Europa, Ganymede and Callisto in 1610. The latest count of 79 known planets includes eight that have not been seen for several years. Saturn is next with 61, followed by Uranus with 27 and Neptune with 14. Mars has two, Earth has one and Mercury and Venus have none. </s> Astronomers have discovered a dozen new moons orbiting Jupiter, but one could spell disaster for the others - 1km-wide "oddball" moving in the opposite direction to the other 78 objects circling the gas giant.A team led by Scott S. Sheppard from Washington DC's Carnegie Institution for Science first spotted the moons in 2017 while on the hunt for a possible massive planet beyond Pluto. Sheppard's discovery brought the total number of objects orbiting Jupiter to 79 - but he said one discovery stood out in particular."This is an unstable situation," said Sheppard. "Head-on collisions would quickly break apart and grind the objects down to dust."The team at the Carnegie Institution think that the oddball moon - potentially to be named Valetudo, after the Roman god Jupiter's great-granddaughter - may represent the leftovers of a former larger moon.Gareth Williams at the International Astronomical Union's Minor Planet Center used the team's observations to calculate orbits for the newly-found moons. "It takes several observations to confirm an object actually orbits around Jupiter," Williams said. "So, the whole process took a year." </s> (CN) — After a year of peering deep into the outer edge of space, Carnegie scientists have discovered 12 new moons orbiting Jupiter.

Carnegie Science researchers first spotted the newly discovered moons in the spring of 2017 as they searched for objects at the edge of the solar system, far beyond Pluto.

“Jupiter just happened to be in the sky near the search fields … so we were serendipitously able to look for new moons around Jupiter while at the same time looking for planets at the fringes of our solar system,” Carnegie team leader Scott S. Sheppard said.

Jupiter has at least 79 moons orbiting it — the most of any planet in the solar system.

Scientists said the group of moons includes one “oddball” moon that is more distant than the others and has an orbit that crosses nine other, outer retrograde moons.

Retrograde moons orbit in the opposite direction of their parent planets. Prograde moons orbit in the same direction.

Sheppard said retrograde moons are “captured moons,” captured by Jupiter’s gravity as they approached it from the opposite direction and became retrograde in their orbits. If an object approaches Jupiter from behind, it is captured as a prograde and will orbit Jupiter in the same direction as it rotates.

The fact that the smallest moons in Jupiter’s orbital groups are abundant suggests the collisions that created them occurred after the era of planet formation, when a rotating disc of gas and dust surrounded the Sun.

This is important research, Sheppard said, because the influences that shape a moon’s orbital history provide information about our solar system’s early years.

He said a moon’s retrograde orbital direction means it’s likely to have a head-on collision with nearby prograde moons.

“This is an unstable situation,” Sheppard said. “Collisions would quickly break apart and grind the objects down to dust.”

This tendency to collide may be what caused orbital moon groupings that were formed eons years ago, Sheppard said.

Jupiter’s distant retrograde moons could be the remnants of three parent systems that broke apart during collisions with asteroids, comets or other moons, Sheppard said. The newly discovered retrograde moons take about two years to orbit Jupiter.

The name “Valetudo” has been proposed for the new oddball moon, Sheppard said. Valetudo was the Roman god Jupiter’s great-granddaughter, who was the goddess of health and hygiene.

Valetudo is a small moon, less than 1 kilometer in diameter.

Sheppard’s team in 2014 discovered Planet X — the object that is the farthest away in our solar system, even beyond Pluto.

Carnegie Science teams used the Blanco 4-meter telescope at Cerro Tololo Inter-American in Chile — one of the largest telescopes in the world — in their work to find the 11 new moons of Jupiter.

The discovery took “a lot of hard work,” Sheppard said. “It took over one year of constant observations to determine that these 12 objects were moons of Jupiter.” </s> The solar system's largest planet has some "new" neighbors.

Astronomers have discovered 12 additional moons orbiting Jupiter, bringing the total to 79, the most of any planet in the solar system, a new study found.

The moons were discovered while astronomers were searching for objects at the edge of the solar system, according to Scott Sheppard, a scientist at the Carnegie Institution for Science who co-authored the study.

“Jupiter just happened to be in the sky near the search fields where we were looking for extremely distant solar system objects, so we were serendipitously able to look for new moons around Jupiter while at the same time looking for planets at the fringes of our solar system,” Sheppard said.

One of the objects they were looking for is the mysterious "Planet X" or "Planet Nine," which remains undiscovered.

The discovery of the new moons was reported Tuesday in the Minor Planet Electronic Circular, a publication of the International Astronomical Union.

Researchers say the new Jupiter moons weren’t seen before because they are tiny – the biggest ones are only about two miles across.

One of the newly discovered moons is an "oddball," Sheppard said. "It has an orbit like no other known Jovian moon,” he explained. It orbits in an opposite direction from the other moons near it, meaning head-on collisions are much more likely to occur.

“This is an unstable situation,” said Sheppard. “Head-on collisions would quickly break apart and grind the objects down to dust.

“It’s also likely Jupiter’s smallest known moon, being less than one kilometer (0.6 mile) in diameter."

Telescopes in Chile, Hawaii and Arizona were used for the original discovery and year-long confirmation of the moons.

“It takes several observations to confirm an object actually orbits around Jupiter,” said Gareth Williams of the International Astronomical Union’s Minor Planet Center. “So, the whole process took a year.”

Legendary Italian scientist Galileo first detected Jupiter’s four largest moons, Io, Europa, Ganymede and Callisto in 1610. </s> Astronomers searching for signs of a large planet far beyond Pluto have stumbled across 12 previously undetected moons orbiting Jupiter, pushing the giant planet's total to a record 79, the Carnegie Institution reported Tuesday.

"Jupiter just happened to be in the sky near the search fields where we were looking for extremely distant solar system objects," Scott Sheppard, leader of the Carnegie team, said in a statement. "So we were serendipitously able to look for new moons around Jupiter while at the same time looking for planets at the fringes of our solar system."

Nine of the newly discovered moons are part of an outer group that orbit in the opposite, or retrograde, direction of Jupiter's spin, taking about two years to complete one trip around the planet. The new moons were found in three distinct clusters and are thought to be debris left over when three larger bodies were broken apart in earlier collisions.

Two previously undetected moons were found closer in, part of a group that orbits in the same "prograde" direction as Jupiter's rotation. With orbital periods of about one year, they also are thought to be the result of earlier collisions.

Sheppard described the 12th new moon as an "oddball" with "an orbit like no other known Jovian moon. It's also likely Jupiter's smallest known moon, being less than one kilometre (0.62 miles) in diameter."

Dubbed Valetudo after the Roman god Jupiter's great-granddaughter, the tiny moon orbits in the prograde direction but at a greater distance from Jupiter, taking about a year and a half to complete one trip around the planet. As such, the orbit crosses those of the outer retrograde moons, raising the possibility of a possible head-on collision at some point in the future.

"This is an unstable situation," said Sheppard. "Head-on collisions would quickly break apart and grind the objects down to dust." </s> Jupiter has had its share of visitors. The Pioneer 10 and 11 spacecraft, as well as Voyagers 1 and 2, flew by the gas giant in the 1970s. Ulysses, Cassini, and New Horizons all passed by the planet for gravity assists to get to their ultimate destinations. The Galileo probe orbited Jupiter from 1995 to 2003, and Juno has been there since 2016.



It may come as a surprise, then, that astronomers still find new moons orbiting the largest planet in the solar system. But 12 more moons were just discovered, bringing the total to 79, the most of any planet that orbits the sun. These small moons were not discovered by a spacecraft, but rather by powerful telescopes on Earth—and by a team, led by Carnegie Institution for Science astronomer Scott Sheppard, that didn't even set out to look for them.

"These moons are the last remnants of the objects that the planets were built from," Sheppard tells Popular Mechanics via email. "Most of the small objects that helped build the planets we see today were incorporated into the planets themselves, and these moons are all that remains."

11 New Moons and an Oddball

Two of the new moons were actually announced last year, but all of them were spotted at roughly the same time around 2017.

"It takes several observations to confirm an object actually orbits around Jupiter, so the whole process took a year," says Gareth Williams of the International Astronomical Union Minor Planet Center, who calculated the orbits of the new moons, in a press release.

The majority of the new moons, which range from about one to three kilometers in diameter (0.6 to 1.8 miles), were initially discovered with the Blanco 4-meter telescope in Chile. Additional telescopes in Chile, Arizona, and Hawaii were used to confirm their existence and determine their orbits.

The new moons orbit in two separate groups. Two of the small satellites were found orbiting in the "prograde group," a collection of moons that hang out just outside the four large Galilean moons (Io, Europa, Ganymede, and Callisto). The moons are so named because they orbit in prograde, or the same direction that Jupiter spins on its axis, completing an orbit in a little less than a year. The 10 remaining moons orbit in the farther-out "retrograde group"—a group of moons that orbit in the opposite direction of Jupiter's rotation, circling the planet about every two years.

There is one mysterious moon among the retrograde group that goes against the tide, traveling in the prograde direction. This oddball—nicknamed Valetudo for the Roman goddess of health and hygiene, one of Jupiter's great-granddaughters—is possibly Jupiter's smallest moon, less than a kilometer in diameter. It is thought to be the last surviving remnant of a larger moon that broke apart during a series of collisions as the planetary system was forming.

"There appear to be groups of moons with very similar orbital properties, which suggests there were once bigger moons that broke apart and we are now seeing the fragments of once bigger moons," Sheppard says. "We think there were originally three retrograde moons each around 100 km in size, but each of these parent moons were broken apart by collisions in the past with something."



That something could have been Valetudo—or the former large moon that it came from.

"We believe the oddball moon, which we are calling Valetudo, was captured in the opposite direction than the retrograde moons," Sheppard says. "Valetudo is like driving down the highway on the wrong side of the road. ... Valetudo likely has collided with some of the retrograde moons in the past, and what we see today is the last remnant of a once much larger moon that has now been ground to dust."

While the original, larger Valetudo was smashed in violent collisions, the smaller remnant that exists today is probably safe—for now. "Valetudo... is likely to collide with a retrograde object head-on every billion years or so," Sheppard says, which means it could have happened multiple times in the 4.5-billion-year history of the solar system, but is highly unlikely to occur again anytime soon.

The two small moons discovered in the prograde group also likely came from a common original body that was destroyed in collisions. It just goes to show how chaotic and violent planetary formation can be.

Sheppard and his team were not even searching for Jovian moons at first, but hunting for a hypothetical giant planet in the distant realms often called Planet Nine or Planet X. In 2014, Sheppard's team announced the discovery of the celestial body with the most distant known perihelion, or closest approach to the sun. The likely dwarf planet 2012 VP "never gets closer to the sun than 80 AU [Astronomical Units]," he says.

While looking for these extremely distant objects, Jupiter happened to wander into the team's field of view. "We knew Jupiter was near our observations for distant planets and dwarf planets that are beyond Pluto, so we specifically designed our observations to be able to search for new moons of Jupiter while also searching for much more distant solar system objects," Sheppard says.

Fortuitously, the same technique for finding far-flung objects orbiting the sun works to search for small objects orbiting Jupiter. "Both surveys take two images of the same sky location separated by a few hours," Sheppard says. "We then look for objects that have moved between the two images." While distant stars will not move in a few hours, objects beyond Pluto and moons orbiting Jupiter will.



Seventy-nine is an impressive number of Jovian moons, but Sheppard says there are likely more waiting to be discovered. "We think there are some 100 moons larger than 1 km around Jupiter... so a few more left to find." </s> Jupiter got 12 new moons on Tuesday, July 17. Well, not exactly. Those dozen moons have, of course, always been in Jupiter’s orbit, but it was only this week that researchers from the Carnegie Institution for Science announced their discovery. The addition of these 12 brings the total number of moons (that we know of) to a whopping 79. As you might imagine, that’s far more than any other planet in our solar system can boast.

While the research team has suspected the existence of these 12 moons for about a year, it takes several observations in order to confirm that an object is, in fact, orbiting Jupiter. As such, the team took their time in confirming the new Jovian moons.

Scientists made their latest discovery when they were actually looking for another extraterrestrial body — Planet X, the planet that is suspected to exist somewhere beyond Pluto.

“Jupiter just happened to be in the sky near the search fields where we were looking for extremely distant solar system objects, so we were serendipitously able to look for new moons around Jupiter while at the same time looking for planets at the fringes of our solar system,” team leader Scott S. Sheppard said in an announcement. Of the 12 new moons discovered, 11 are described as normal moons, while the other is an “oddball.”

What makes it weird? Apparently, it’s just 1 kilometer wide, which means it’s the smallest moon scientists have discovered to date orbiting the planet, and it takes a full year and a half to make a complete trip around Jupiter. Moreover, its orbit crosses that of other moons in retrograde (those that travel in the opposite direction of Jupiter’s rotation), which is to say that at some point, multiple moons could collide. “This is an unstable situation,” Sheppard noted. “Head-on collisions would quickly break apart and grind the objects down to dust.”

This discovery could actually give scientists clues into the formation of moons and planets as a whole. As the team noted in its announcement, “Elucidating the complex influences that shaped a moon’s orbital history can teach scientists about our Solar System’s early years.” In this case, determining that there are still several small moons surrounding Jupiter suggests that they were actually created after the planets were formed.
Ten new moons are discovered around Jupiter, raising the count to 79 confirmed moons. One of these new moons, S/2016 J 2, nicknamed Valetudo, is notable for orbiting backwards compared to the other moons in its vicinity, and may collide with one of them in the future.