Scientists discover 12 new Jupiter moons, describe one as an "oddball"

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It now has the largest amount of known moons around a planet in the solar system, but there's something very peculiar about one of the recently discovered Jovian satellites. He has also been involved in the discovery of 25 of Saturn's known moons, two moons around Uranus and one orbiting Neptune, two comets, and over a dozen minor planets, which includes the farthest known object of the solar system - 2012 VP113(nicknamed Biden).

Researchers in the U.S. 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.

They also have a retrograde orbit, or the opposite direction to the spin of Jupiter on its axis.

Valetudo orbits Jupiter in the same direction that the planet spins, but a bunch of other small moons share the same orbital path while travelling in the opposite direction.

So, unlike the closer-in prograde group of moons, this prograde moon has an orbit that crosses the outer retrograde moons.

"They did not form with the planet, but were likely captured by the planet during or just after the planet-formation epoch", says Scott Sheppard, an astronomer at the Carnegie Institution for Science in Washington DC. "Head-on collisions would quickly break apart and grind the objects down to dust". The researchers think these moons are also fragmented remnants of larger moons broken apart after colliding with another body.

During a quest to find Planet Nine, a mysterious planet believed to be on the edge of our solar system, astronomers discovered something else: 12 new moons around Jupiter.

As a result, head-on collisions are much more likely to occur between the "oddball" prograde and the retrograde moons, which are moving in opposite directions.


The initial discovery of most of the new moons were made on the Blanco 4-meter telescope at Cerro Tololo Inter-American in Chile and operated by the National Optical Astronomical Observatory of the United States.

Sheppard, Chad Trujillo of Northern Arizona University and David Tholen of the University of Hawaii are on a quest to find as many faint, distant objects on the edge of the solar system as they can. Each takes about two years to circle the planet. He explained that the institution had named the moon Valetudo, and while that may sound like Latin for Mommy's Special Little Boy, it's really the Roman god Jupiter's great-granddaughter.

The moons Sheppard spied are farther-flung and tiny, each no more than two miles in diameter. Because of that small moon's orbit, it may be eventually be destined for an crash.

There are almost 200 moons in our solar system.

The orbits of the 9 newly discovered retrograde moons of Jupiter are shown here. "By looking at these outer moons", he said, "we can get an insight into what the objects were like that ended up forming the planets we see today".

Scientists believe moons like Valetudo and its siblings appeared soon after Jupiter formed.

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. That puts them in the category known as retrograde moons.

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