The moons were first discovered during the search for Planet X, the hunt for a massive planet beyond Pluto. His team at Carnegie, along with collaborators at the University of Hawaii and Northern Arizona University, was hunting for objects far beyond Pluto.
Researchers in the USA stumbled upon the new moons while hunting for a mysterious ninth planet that is postulated to lurk far beyond the orbit of Neptune, the most distant planet in the solar system. Confirmation of the moons required multiple observations, and those data enabled a calculation of the moons' orbits. "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.
Nine of the new moons are part of a distant outer swarm of moons that orbit in the opposite direction of Jupiter's spin. The newly discovered retrograde moons take about two years to orbit Jupiter.
But what's particularly wild about these newly discovered moons is that researchers weren't even looking for them.
Scientists have discovered 12 previously unknown moons orbiting Jupiter, and one of them is a real oddball.
Nine of the new moons belong to an outer group that orbit Jupiter in retrograde, meaning they travel in the opposite direction to the planet's spin.
The moon we see today is the remainder of a much bigger world that blew apart after the crashes.
Because Valetudo's orbit crosses the orbits of some of the outer retrograde moons, it's possible that it suffered a head-on collision in the past. These are part of a group of prograde moons that orbit closer to Jupiter than the retrograde moons do.
"This is an unstable situation", said Sheppard. "Head-on collisions would quickly break apart and grind the objects down to dust".
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.
Valetudo might be the last fragment of a larger moon that was destroyed by the retrograde moons, and its path means it too might eventually get demolished.
Astronomers have proposed the name "Valetudo" for the oddball moon, after the Roman god Jupiter's great-granddaughter, the goddess of health and hygiene.
But that didn't necessarily suggest they were moons - they could have been asteroids orbiting the sun.
Due to their sizes-one to three kilometers-these moons are more influenced by surrounding gas and dust.
With 67 other known moons flying around Jupiter, there's already a good amount of traffic around the gas planet, as shown in the illustration above.
As part of that search, Sheppard was using the 4-meter Víctor Blanco Telescope in Chile in March of a year ago and realized that Jupiter was right near the part of the sky he wanted to search. That makes it a powerful tool for surveying the night sky in search of faint objects.
This research was partially funded by a NASA Planetary Astronomy grant and includes data gathered with the 6.5-meter Magellan Telescopes. So the researchers had to continue observations.
Credit: Carnegie Institution for Science. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.