The researchers were searching for the proposed "Planet X" or "Planet 9", which astronomers believe exists and could account for the way distant objects orbit in a similar manner. Confirmation came with help from a variety of observatories, including the 6.5-metre Magellan telescope at Carnegie's Las Campanas Observatory in Chile, the 4-metre Discovery Channel Telescope at Lowell Observatory in Arizona, the 2.2-metre University of Hawaii telescope and the 8-metre Subaru and Gemini Telescopes, also in Hawaii. While the retrograde moons orbit in a clockwise direction, Valetudo travels in a counter-clockwise direction. That puts them in the category known as retrograde moons. "It's also likely Jupiter's smallest-known moon, being less than 1km (0.6 of a mile) in diameter". This swarm may have originally been three separate moons that broke apart after collisions. Two of the newly discovered moons were found among these prograde moons, and take a little less than a year to go around in their orbit once. The satellite, named for Jupiter's great-granddaughter, could be a bit of unfinished business, the last remnant of the ancient moons that provided the grist for the retrograde cluster, the team theorizes.
It has most likely collided with other moons, breaking it down into the fragment it is today. They are thought to be the remnants of larger parent bodies that were broken apart in collisions with asteroids, comets and other moons. It's also the smallest known moon of Jupiter, scientists said. It has a prograde orbit at a distance where the rest of Jupiter's moons have retrograde orbits.
A greater number of irregular moons because it tells us about a time during Jupiter's formation when the planet was still growing.
Nine of the found moons are part of the distant retrograde group that orbit in the opposite direction of Jupiter's spin rotation, according to Carnegie Institution for Science. They were looking for Planet Nine.
'I accept' U.S. intelligence findings on Russian meddling
Kansas Senator Jerry Moran says Trump missed an opportunity to publicly condemn Russia's interference in USA elections. The US and Russian presidents held almost two hours of closed-door talks in the Finnish capital Helsinki on Monday.
"So we were serendipitously able to look for new moons around Jupiter while at the same time looking for planets at the fringes of our Solar System", Dr Sheppard added.
"This moon is going down the highway the wrong way", Sheppard said.
Sheppard described the 12th new moon as an "oddball" with "an orbit like no other known Jovian moon". And astronomers have just announced the discovery of a dozen more.
During its full opposition the planet was brightest in Britain on May between 9:30pm and 4:30am BST while in the USA it peaked on May 9 between 1:10am and 6:20am ET.
The remaining moon is less than a kilometer across, further out than the two conventional moons and has a 1.5-year orbit-and the orbit is inclined.
Sheppard and his colleagues speculate that Valetudo was probably once much larger, but was ground down, over the course of billions of years, as a result of collisions. Their existence shows that they were likely formed after this gas and dust dissipated.