Twelve new moons have been discovered orbiting Jupiter, raising the number of natural satellites known to be circling our solar system's biggest planet to 79. One of the newfound moons, provisionally named "Valetudo" for the Roman goddess of health and hygiene and the great-granddaughter of the god Jupiter, is being called an oddball because it orbits Jupiter in the opposite direction of nearby moons. "'Valetudo' is like driving down the highway on the wrong side of the road," astronomer Scott S. Sheppard, a staff scientist at the Carnegie Institution for Science in Washington and the leader of the team of astronomers who made the discovery, told NBC News MACH in an email. Carnegie Institution for Science The astronomers spied the moons in the spring of 2017 while using a giant telescope in Chile to search for Planet X, a massive and as-yet-undiscovered planet that is believed to orbit the sun far 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," Sheppard said in a statement. The discovery, which was confirmed by observations made with several other telescopes, delighted other astronomers. This animation shows, in red, the orbits of nine of the newly discovered moons as well as the 'oddball' Valetudo, in green, moving in the opposite direction. The other two moons are closer to the planet, shown in blue. Roberto Molar-Candanosa / Carnegie Institution for Science "I love this result," Jackie Faherty, an astronomer with the American Museum of Natural History in New York who was not part of the team, said in an email. "We've been studying this planet for as long as we have been looking up, and it is still yielding surprises for us. It also reminds me that the question of 'what is out there' is always an open one to be explored." Tabetha Boyajian, an astronomer at Louisiana State University in Baton Rouge who also was not part of the team, called the discovery of the new moons "cool" in an email. "No surprise to me that it is hoarding more moons," she said of Jupiter, adding that "studying the dynamical history of such objects can tell us a lot about solar system formation." With a diameter of less than one kilometer, Valetudo is believed to be Jupiter's smallest moon. Ganymede, Jupiter's largest moon and the biggest in the solar system, has a diameter of about 5,300 kilometers (about 3,300 miles). That's bigger than the planet Mercury. Sheppard said Valetudo's composition was likely "half ice and half rock," adding that the tiny satellite is the "last remnant of a once much larger moon that has been ground to dust from collisions" with other Jovian moons. Jupiter might yet have more undiscovered moons, Sheppard told Nature. But its total lunar tally already far exceeds that of any other planet — including Saturn, whose 62 confirmed moons make it the runner-up. WANT MORE STORIES ABOUT THE SOLAR SYSTEM? FOLLOW NBC NEWS MACH ON TWITTER, FACEBOOK, AND INSTAGRAM.<doc-sep>A dozen new moons have been found orbiting Jupiter, including 11 normal moons and one "oddball" moon, according to Carnegie Institution for Science. The new discovery brings Jupiter’s total number of moons to 79, the highest of any planet in solar system, the institute said in a statement. A group of scientists, led by Scott S. Sheppard, first spotted the moons in 2017 while they were searching for very distant Solar System objects that could be possible massive planet far beyond Pluto, the statement read. "Understanding these moons helps us understand what the planets were originally made from," Sheppard told ABC News via email, adding that the moons are "likely half ice and half rock." The oddball moon, which they named Valetudo, was captured in the opposite direction from the retrograde moons. "Valetudo is like driving down the highway on the wrong side of the road. That is, 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 said. "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 none been ground to dust from collisions in the past." He believes that there may be more astronomical secrets found near the large planet. "We think there are more moon fragments yet to be found around Jupiter," Sheppard said, "but technology will need to get better for us to find them." The observations to confirm the objects actually orbits around Jupiter took about a year, according to Gareth Williams at the International Astronomical Union’s Minor Planet Center. The center used the Carnegie insitute's observations to calculate the orbits of the newly found moons. "Nine of the new moons are part of a distant outer swarm of moons that orbit it in the retrograde, or opposite direction of Jupiter’s spin rotation," the statement said. "These distant retrograde moons are grouped into at least three distinct orbital groupings and are thought to be the remnants of three once-larger parent bodies that broke apart during collisions with asteroids, comets, or other moons." The newly-discovered retrograde moons are estimated to take about two years to orbit Jupiter. "Several space agencies are sending spacecraft to Jupiter in the next decade," Sheppard said. "It is likely one of these spacecraft will fly by one of these distant Jupiter moons to get a close-up view." When that happens, he said, many more questions may be answered. "What is the original material that built the planets?" Sheppard said. "That is what we are trying to answer."<doc-sep>Jupiter is often described as a solar system in miniature. The gas giant is made out of the same basic ingredients as the sun — hydrogen and helium — and is surrounded by an array of geologically diverse moons. Today, the Jupiter system grows even more impressive. The International Astronomical Union has confirmed the discovery of 10 new moons, bringing the grand total to 79. This discovery includes one very odd moon that helps explain why there are so many others. Where have these moons been all this time? How could 10 moons just go unnoticed, you ask? The short answer: These moons are relatively tiny, just a couple miles across or smaller. And even with high-powered telescopes, it can be very hard to spot small, dim objects next to something as massive and luminous as Jupiter. “As our technology gets better and better, we’re able to look fainter and fainter, so we’re discovering smaller and smaller moons,” said Scott S. Sheppard, the Carnegie Institution for Science astronomer who led the discoveries. These new moons were discovered using a 520-megapixel camera attached to the huge Victor M. Blanco Telescope in Chile. (For reference: The latest iPhone has a 12-megapixel camera.) The camera not only has a dense resolution, it’s also specially calibrated to find faint objects. Also, Jupiter’s gravity is so strong, it can keep objects in orbit up to 18.6 million miles away. (Recall that our moon is just 239,000 miles away.) This means there’s a lot of space around Jupiter for astronomers to examine that could possibly contain moons. How to discover moons of Jupiter Sheppard and his team weren’t actually looking for the new moons when they discovered them — they were looking for other far-flung and hard-to-spot objects out past Pluto. When their telescope scans the sky, it takes in objects at all distances. It can spot stars millions of light-years away. It can spot Kuiper belt objects near the edge of the solar system. And it can see objects closer to home, like the eight planets. All of those objects could be in the same image. It’s the motion of these objects over a period of time that tells astronomers what and where they are. “It’s like when you’re driving in your car,” Sheppard explains. “When you look out the side of the road, the street signs are flying by really fast as you are driving, and the mountains in the background are moving very slow.” Slower objects are farther away. And if an object is moving at the same speed as Jupiter, it’s likely in the same location. The team first noticed the moons in 2017, but they needed a year of follow-up observations to chart the shape of their orbits and to confirm they weren’t actually asteroids or comets orbiting the sun. Here’s what the telescope actually captured. Most of the white dots in the photo are stars. But you can see a moon, marked with orange lines on either side, moving ever so slightly from one frame to the next. This was the big clue it was a moon of Jupiter. It was moving against a background of static stars. Humans have been discovering moons of Jupiter since Galileo spotted the first four large ones — Callisto, Io, Europa, and Ganymede — in 1610. It’s not exactly a shock that we’re still discovering them, considering how our telescopes are getting better and better at making out the faintest of objects. Two moons were announced just last year. And Sheppard suspects there are still more to find. Only one of the moons has a name for now. Introducing Valetudo. Nine of the moons remain nameless (for now). But one special one has been named. It’s called Valetudo, named after the Roman goddess of health and hygiene. New Jupiter moons are named after Roman gods related to Jupiter. Valetudo is Jupiter’s great-granddaughter. And adorably, Sheppard chose Valetudo as a nod to his girlfriend, whom he describes as a “very cleanly person.” Moons close to Jupiter tend to orbit in a “prograde” motion, meaning in the same direction as Jupiter’s rotation. Those farther away rotate in a retrograde motion. But Valetudo is an odd duck. It’s orbiting in a prograde motion in the retrograde region. “It’s like driving down the highway the wrong way,” Sheppard says. “It’s going around Jupiter in one direction, and there’s, like, 40-something objects going around Jupiter in the other direction.” This means it’s “very likely to have some sort of head-on collision over time,” he says. And that’s actually an important clue to why there are so many moons around Jupiter. Sheppard explains that a long time ago, there were probably fewer, larger moons orbiting Jupiter in this retrograde region. But over time, they were broken into pieces. It’s possible that Valetudo — or a larger previous version of it — was the destructive force behind the collision. Imagine the chaos that would ensue if a tractor-trailer was driving against traffic on a highway; that’s Valetudo. And that possibly “gives us this whole swarm of objects we see today,” Sheppard says. There’s still a lot that’s unknown about these moons, like what they exactly look like or what they’re made of. NASA’s Juno spacecraft, which is currently orbiting Jupiter, is not in a position to image them. It will take a future mission to Jupiter to get a clearer view of the moons. The only things we know about them are their approximate sizes and the shape of their orbits. But if we do investigate them further, they might also reveal clues about the origin of our solar system. The outer planets — Jupiter, Saturn, Uranus, Neptune — were formed by vacuuming up smaller objects in their paths. And the objects that weren’t consumed were captured in their orbits. “These outer moons,” Sheppard says, “are like the last remnants of the planetesimals, the first objects that formed our solar system.” Further reading: Jupiter, the king of planets<doc-sep>Jupiter is the largest and most massive of all the solar system’s planets, so it’s no surprise it has a lot of moons. Galileo discovered the four biggest ones back in the 17th century, and a lot of smaller ones have been found as telescopes and techniques have improved. Even so, it’s a bit of a surprise to see that this week astronomers announced finding an even dozen more moons orbiting the king of the planets! Even better, they were found as a kind of bonus. The astronomers were looking for Kuiper Belt Objects (or KBOs), icy bodies orbiting the Sun beyond Neptune. If there’s another planet orbiting the Sun way, way far out — the so-called Planet Nine — then its gravity may affect the orbits of these KBOs, allowing astronomers to figure out where this possible planet is. That was the primary purpose of the observations, but it so happens that Jupiter was nearby in the sky where they were looking. If there were previously undiscovered moons in far-flung orbits around Jupiter, they might spot them, too. Zoom In Orbits of twelve new moons found for Jupiter (not to scale). Some orbit the same way Jupiter spins (blue), and others the opposite way (red). Credit: Carnegie Institution for Science / Roberto Molar Candanosa And so they did. The observations were made in 2017, but it took a year to track them long enough to nail down their orbits. Some of them are so far from Jupiter that they take two years to travel around it once! And what doesn’t surprise me at all is that they’re weird. This happens every time we push observations to the limits, looking for faint, small beasties, and these new moons don’t disappoint. Video of SheppardJupiterMoonsMovie Nine of the moons are very distant from Jupiter, and orbit it retrograde — backward relative to Jupiter’s spin. Most big objects in the solar system orbit the Sun and spin in the same sense (the motion is counterclockwise when looking down from above the Earth’s north pole). Since all these objects formed from the same spinning disk of gas and dust when the solar system was born, this makes sense (and in fact was why this formation mechanism of the Sun and planets was first proposed decades ago). But these moons orbit clockwise, indicating a different formation mechanism. They may have started off as asteroids orbiting the Sun prograde, but were captured by Jupiter’s ridiculously strong gravity. If the geometry were just right, these objects could then find themselves orbiting Jupiter retrograde; we do see this in other moons of the outer planets. Not only that, but when the orbital characteristics (shape, tilt, and so on) are compared, these nine retrograde moons seem to fall into three groups; that implies that each group used to be a single moon that got smashed somehow, possibly a collision with another moon-sized body. The remaining pieces separated but still held on to the same sorts of orbits. Zoom In Images of the tiny moon Valetudo, showing its motion against the background stars. Credit: Carnegie Institution for Science Two of the new moons orbit Jupiter closer in, and are prograde. The twelfth moon, though, is the weirdest of all. Given a provisional name Valetudo (the great-granddaughter of Jupiter in mythology*), it orbits prograde, but is also so far from Jupiter that its orbit is solidly among the retrograde moons! That’s very surprising, because in the long run such an orbit is bad news. When moons move all in the same direction, collisions are less likely, as when a bunch of cars are all driving in the same direction on one side of the highway. But now put a car moving in the wrong direction in that lane, and things will go downhill fast. Over the lifetime of the solar system, a collision seems inevitable. That implies this moon (or the retrograde moons) are literally new, captured recently compared to the age of the solar system itself. It’s possible to delay the inevitable if the orbits are slightly tilted with respect to one another, but even then, given enough time, bang. And in fact all the groups of shattered retrograde objects do lend credence to this idea. They must’ve hit something in the past. Valetudo is the smallest of the moons discovered, likely just under a kilometer wide (the size isn’t measured directly — it’s too small — but estimated from its brightness). It’s also possibly the smallest moon known around the planet. The other newly discovered range up to three kilometers in diameter. Incidentally, this brings the total known moons of Jupiter to 79. That’s the most of any planet. This is all cool, and shows there’s a lot to learn about our system’s planets, even ones very well studied. It also makes me wonder if there’s a lower limit to what we’d call a moon. Imagine if we find a rock that’s, say, 10 meters across. Is that properly a moon, or just a bit of debris? What about the trillions of icy particles in Saturn’s rings? Of course, none of these objects care what we call them. It’s better not to fret too much on that, and instead focus on the rich diversity of worlds and worldlets in our neighborhood. There’s still so much left to see, so much left to discover! * In Greek mythology, the goddess of health was Hygieia. This was then appropriated by the Romans (as they did) and renamed Valetudo. The fourth largest asteroid is named Hygieia, so that name was already taken for the moon! Valetudo isn’t official, but has been proposed, and all the moons may eventually be given names by the International Astronomical Union.<doc-sep>
Ten more moons have been confirmed to orbit around Jupiter, bringing the planet’s total known satellite count to 79. That’s the highest number of moons of any planet in the Solar System. And these newly discovered space rocks are giving astronomers insight as to why the Jupiter system looks like it does today. Astronomers at Carnegie Institution for Science first found these moons in March 2017, along with two others that were already confirmed in June of last year. The team initially found all 12 moons using the Blanco 4-meter telescope in Chile, though finding these objects wasn’t their main goal. Instead, they were searching for incredibly distant small objects — or even planets — that might be lurking in our Solar System beyond Pluto. But as they searched for these fringe space rocks, they decided to take a peek at what might be lurking around Jupiter at the same time. Now, the moons they found have been observed multiple times, and their exact orbits have been submitted for approval from the International Astronomical Union, which officially recognizes celestial bodies. One moon is “basically driving down the highway in the wrong direction” These moons are all pretty tiny, ranging between less than a mile and nearly two miles wide. And they break down into three different types. Two orbit closer to Jupiter, moving in the same direction that the planet spins. Farther out from those, about 15.5 million miles from the planet, there are nine that revolve in the opposite direction, moving against Jupiter’s rotation. But in this same distant region, one strange moon that astronomers are calling Valetudo is moving with Jupiter’s spin, like the two inner moons. That means it’s going in the opposite direction of all the other moons in the same area. “It’s basically driving down the highway in the wrong direction,” Scott Sheppard, an astronomer at Carnegie who led the discovery team, tells The Verge. “That’s a very unstable situation. Head-on collisions are likely to happen in that situation.” Valetudo isn’t the only moon of Jupiter that acts this way. Another moon called Carpo also orbits far out from Jupiter, moving in the opposite direction of many other moons in the area. However, Valetudo orbits much farther away than Carpo, and it may actually be the smallest moon Jupiter has. Now with this discovery, astronomers think it’s good evidence that moon-on-moon collisions have happened in Jupiter’s past, and these are responsible for the lunar landscape around the planet today. “Valetudo, at just 1 kilometer across, is probably the last remnant of a much larger moon that’s been ground down into dust over time,” says Sheppard. Finding moons around Jupiter can be tough. As the biggest planet in our Solar System, it has a very large area of influence, so there’s a lot of space where moons could potentially be. It’s difficult to search that area in a timely manner with a telescope. “It’s like looking through a straw, and you’re just covering as many points around Jupiter as you can looking for these things,” says Sheppard. And since Jupiter is so large, it reflects a whole lot of light. That means there can be a lot of glare when searching for super faint moons around the planet. Fortunately, the Blanco 4-meter telescope the scientists were using was the perfect piece of equipment to find these moons. It has the largest camera of any large-class telescope out there, and it allowed the astronomers to cover a big area of space around Jupiter in a shorter amount of time. Additionally, Blanco’s camera is well-shaded, according to Sheppard, which helped reduce the glare and scattered light from Jupiter. this new crop of moons tells a big story about Jupiter’s past This also makes Blanco adept at finding incredibly distant, faint objects, which is why the Carnegie scientists have been using the telescope to do a massive survey of bodies beyond Pluto. While scanning the night sky in March of last year, the team noticed that Jupiter happened to be directly overhead in the sky. So they decided to multitask: they would search for objects moving at roughly the same rate as Jupiter — potential moons — as well as objects moving much more slowly in the distant Solar System. After identifying 12 possible Jupiter moons, they reobserved the planet a month later and then again in May of this year with different telescopes to confirm what they had seen.