Astronomers are still finding moons at Jupiter, 400 years after Galileo used his spyglass to spot the first ones.
He added that the team was able to look for new moons "serendipitously".
Credit: Carnegie Institution for Science. Seven fall in a farther out "retrograde" cluster (red) rotating against the planet's spin, their opposing path kickstarted when ancient moons collided with comets, asteroids, or other moons. There are also small interior moons that orbit in the same direction as Jupiter, which are referred to as prograde moons.
Washington, DC-Twelve new moons orbiting Jupiter have been found-11 "normal" outer moons, and one that they're calling an "oddball". The research team thinks Valetudo could be a leftover chunk from a once-larger moon that rammed into another past Jovian satellite, creating the many smaller objects that exist today. But Valetudo, in addition to being the smallest discovered, orbits in prograde, or the same direction as the planet's spin.
In addition to these two groups, Jupiter has "regular" satellites, or moons with almost circular orbits. Most likely to be pieces of a once larger moon that was broken up in orbit, they take almost a year to complete a lap around Jupiter. Jupiter's moons are getting a sense of what that feels like now, with a newly identified resident careening toward conflict with everyone else.
Valetudo can be seen moving relative to a steady background of distant stars in this image.
It's further away than the prograde moons, taking around one and a half years to orbit around the planet. That puts it on a possible collision course with a retrograde moon.
"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. "Head-on collisions would quickly break apart and grind the objects down to dust".
Jupiter's tally of moons just got a little bit larger. "And that's very bad, because head-on collisions are likely to happen".
The tiny moon is likely to be named Valetudo after the Roman god Jupiter's great-granddaughter, the goddess of health and hygiene.
The team had planned to use the observatory's Blanco four-meter telescope to scout for objects way out, beyond Pluto, and they also made a decision to train their gaze on Jupiter's neighborhood in the night sky.
Elucidating the complex influences that shaped a moon's orbital history can teach scientists about our Solar System's early years.
This orbital arrangement means Jupiter appears as the largest disc in the sky and will be visible from sundown to sunrise.
During its full opposition the planet was brightest in Britain on May between 9:30pm and 4:30am BST while in the U.S. it peaked on May 9 between 1:10am and 6:20am ET.
This was at a time when the Sun was still surrounded by a rotating disc of gas and dust from which the planets were born. Of the 12 latest moons to join Jupiter's family, it's a maverick whose odd orbit may give astronomers crucial insights to understanding how the moons of Jupiter came to be. So they were likely formed after they had dissipated.