Twelve new moons orbiting Jupiter have been found—11 “normal” outer moons, and one that they’re calling an “oddball.” This brings Jupiter’s total number of known moons to a whopping 79—the most of any planet in our Solar System. ...
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Nine of the new moons are part of a distant outer swarm of moons that orbit it in the retrograde, or opposite direction of Jupiter’s spin rotation. 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. The newly discovered retrograde moons take about two years to orbit Jupiter.
Two of the new discoveries are part of a closer, inner group of moons that orbit in the prograde, or same direction as the planet’s rotation. These inner prograde moons all have similar orbital distances and angles of inclinations around Jupiter and so are thought to also be fragments of a larger moon that was broken apart. These two newly discovered moons take a little less than a year to travel around Jupiter.
“Our other discovery is a real oddball and has an orbit like no other known Jovian moon,” Sheppard explained. “It’s also likely Jupiter’s smallest known moon, being less than one kilometer in diameter”.
This new “oddball” moon is more distant and more inclined than the prograde group of moons and takes about one and a half years to orbit Jupiter. So, unlike the closer-in prograde group of moons, this new oddball prograde moon has an orbit that crosses the outer retrograde moons. ...
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<<Today, The International Astronomical Union has confirmed the discovery of 10 new [Jupiter] moons, bringing the grand total to 79. These new moons were discovered using a 520-megapixel camera attached to the huge Victor M. Blanco Telescope in Chile. The camera not only has a dense resolution, it’s also specially calibrated to find faint objects.
The team first noticed the moons in 2017, but they needed a year of follow-up observations to chart the shape of their orbits and to confirm they weren’t actually asteroids or comets orbiting the sun.
Nine of the moons remain nameless (for now). But one special one has been named. It’s called Valetudo, named after the Roman goddess of health and hygiene. New Jupiter moons are named after Roman gods related to Jupiter. Valetudo is Jupiter’s great-granddaughter. And adorably, Sheppard chose Valetudo as a nod to his girlfriend, whom he describes as a “very cleanly person.” Moons close to Jupiter tend to orbit in a “prograde” motion, meaning in the same direction as Jupiter’s rotation. Those farther away rotate in a retrograde motion. But Valetudo is an odd duck. It’s orbiting in a prograde motion in the retrograde region.>>