The finds were announced Tuesday in a bulletin from the International Astronomical Union's Minor Planet Center at the Smithsonian Astrophysical Observatory in Cambridge, Mass., which serves as the global clearinghouse for the study of moons, asteroids and comets. Astronomers from the Carnegie Institution for Science have spotted 12 new moons orbiting Jupiter, bringing the total to 79.
A team of astronomers reported the recent discovery of a dozen new moons circling the giant gas planet.
"Jupiter just happened to be in the sky near the search fields where we were looking for extremely distant solar system objects, " Sheppard said, according to a Carnegie Institution news release.
The team had planned to use the observatory's Blanco four-meter telescope to scout for objects way out, beyond Pluto, and they also chose to train their gaze on Jupiter's neighborhood in the night sky.
The inner moons take about a year to circle Jupiter, while the outer moons take twice as long. What makes it odd, however, is its maverick orbit: it is the only prograde Jovian satellite discovered to date to orbit at the same distances as the retrograde moons. Researchers have proposed naming the "oddball" Valetudo, after the Roman goddess of health and hygiene.
This means, unlike those closer to Jupiter, it crosses the outer retrograde moons.
The team also discovered one particularly odd moon in the new batch. So a telescope isn't able to capture much more than the moons' orbits. The other three are prograde, which orbit in the same direction.
The effect of opposition is similar to the effect of the full moon seen once a month when Earth is positioned directly between our natural satellite and the sun. "But over the age of the solar system, a hundred million or billions of years, it looks like it's very likely that Valetudo will collide with one of these retrograde objects", Sheppard said.
When you're scanning space for a distant planet, that's potentially lurking at the far edges of our solar system, it certainly pays off to keep an eye on what's going on a little closer to home! Understanding that smaller moons still exist in the outer regions of Jupiter's orbital regions suggests to astronomers that they formed after the planets. Maybe 100 or more of the really small ones. Of the 12 newly surveyed moons, 11 have orbits that fall neatly in line with previously discovered satellites.
Galileo detected Jupiter's four largest moons, Io, Europa, Ganymede and Callisto in 1610. These all travel in retrograde, or the opposite of Jupiter's rotation, while two more, also though to be moon remnants, travel in prograde. Sheppard said another collision will likely happen during the solar system's lifetime.
Also, if the moons had formed earlier, there likely would have been more crashes, the team explained.
One of the new moons was described as a "real oddball" by researcher Scott Sheppard at the Carnegie Institution for Science, because of its tiny size, it measuring just about a half-mile (one kilometer) across. In the meantime, they're waiting for the IAU to formally accept "Valetudo" as the name for the oddball moon.
In the meantime, "we have to speculate about what they [the new moons] are made of", Sheppard said. Because they formed between the two belts, the moons are probably composed of rock and ice. At the same time, they watched for Planet Nine or smaller, distant dwarf planets in the background.