One of these new moons turned out to be a bit of a rebel.
Scientists classified the findings as 11 "normal" outer moons, and another that they are calling an "oddball" for its odd orbit. It's only about one kilometer in diameter, by far the smallest of the newly discovered moons. He and his team have been photographing the skies with some of today's best telescope technology, hoping to catch sight of this mysterious ninth planet.
Most of the discoveries were made with the Dark Energy Camera on the Blanco 4-metre telescope at Cerro Tololo Inter-American in Chile, operated by the National Optical Astronomical Observatory of the United States.
For example, the discovery that the smallest moons in Jupiter's various orbital groups are still abundant suggests the collisions that created them occurred after the era of planet formation, when the Sun was still surrounded by a rotating disk of gas and dust from which the planets were born. Jupiter is not in the frame, but off to the upper left.
Researchers found the new moons thanks to a telescope upgrade.
"This simulation takes a few months to run and we expect the answer is between about 100 million years and 1 billion years, which is long in human time but not all that long in astronomical time", Sheppard said.
"Valetudo's going down the highway the wrong way, so it's very likely it will collide with these other objects".More news: Thunderstorms, Heavy Rain Headed to MetroWest
The last moon is fittingly weird, considering how freaky Jupiter is.
Because it's orbiting in the opposite direction of the nine "new" retrograde moons, and across their paths, there is a high risk that it will hit one of them, according to the statement.
The team's results are not yet available in a peer-reviewed journal, as Sheppard's team is now running supercomputer simulations to try and figure out how often Valetudo might collide with a retrograde moon.
Beyond these is a group known as the "prograde" moons - more tiny, irregular satellites, all of which travel around Jupiter in the same direction that the planet rotates (counter-clockwise, in the view shown below).
From Jupiter's entire collection of 79 moons, Sheppard has been involved in the discovery of 54 of them, including most of the known retrograde moons. Those eleven moons are probably remnants of larger bodies that got broken up in collisions. That's a lot of moons. A prograde satellite may simply have been floating through the solar system before being captured by Jupiter. The planet must have acted like a vacuum, sucking up all the material that was around it.
"They didn't form with Jupiter", he says. If small moons like these were around when the solar system was still thick with gas and dust, drag forces would have slowed them down and caused them to fall into Jupiter, never to be seen again.
These building blocks of planets can provide a window into the early years of the solar system.
Once they finish running and analyzing the simulations, the team plans to publish the results in early 2019. The more they find, the more they can narrow the area of sky where Planet Nine might be.
The IAU requires moons of Jupiter to have names related to the Roman god Jupiter.