10 Moons Orbiting Jupiter Discovered, One 'Oddball' on a Collision Course

In 2014, the same team of scientists found the object with the most-distant known orbit in the Solar System and was the first to hypothesize the existence of a putative planet popularly called Planet X or Planet Nine The findings include 11 “normal” outer moons, and one that scientists call an “oddball.” Researchers, led by Scott S Sheppard from Carnegie Institution for Science in the US, first spotted the moons in last year while they were looking for a possible massive planet 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,” team leader Scott S. Sheppard said in an announcement. 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. 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. 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. 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. 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. ... 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." "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. "This is an unstable situation," Scott Sheppard of Carnegie says in a statement. “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. 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.
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.