Astronomers discover 12 more moons of Jupiter, including an oddity

Rodiano Bonacci
Luglio 17, 2018

The discovery brings Jupiter's total number of known moons to a whopping 79 - the most of any planet in our Solar System. By this latest count, our solar system's largest planet now has 79 moons, more than any other.

The Blanco 4-meter telescope Sheppard was using is uniquely suited to spotting potential new moons both because the camera installed on it can photograph a huge area of sky at once and because it's particularly good at blocking stray light from bright objects nearby - say, Jupiter - that might wash out fainter ones.

The new moons, pictured as circles above, were discovered previous year by a team of astronomers.

Because Jupiter moves across the sky at a known speed, anything nearby moving at the same speed in the same direction becomes a candidate for a moon - but confirmation is a time-consuming process, Sheppard explained to ScienceAlert. Some slipped in and out of view, complicating the task.

The researchers targeted objects moving with Jupiter in the foreground, which revealed the 12 new moons.

It's further away than the prograde moons, taking around one and a half years to orbit around the planet. Given their distance and angle from Jupiter, they are also most likely pieces of a once-larger moon. Its orbit actually crosses that of the retrograde moons, which means that at some point, they may collide.

The orbits of the twelve newly discovered moons of Jupiter are shown here in bold.

Astronomers have proposed the name "Valetudo" for the oddball moon, after the Roman god Jupiter's great-granddaughter, the goddess of health and hygiene.

Most of the newly discovered moons orbit opposite to Jupiter's spin, what's known as a retrograde orbit.

Nine of the new moons are in the retrograde group, a distant bunch of moons that rotate in the opposite direction of Juipter.

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Our solar system's giant planet has been hiding something - or 12 things, really.

These new moons probably formed in a place in our solar system known as the giant planet region, which is between the asteroid belt, dominated by rocky asteroids, and the Kuiper belt, dominated by icy comets.

The team believes Valetudo might be a fragment of a larger moon, broken off in a collision with a larger retrograde moon, resulting in something like the retrograde groupings observed.

"This is an unstable situation", Sheppard said.

A team led by Carnegie's Scott S. Sheppard first spotted the moons in the spring of 2017 while they were looking for very distant Solar System objects as part of the hunt for a possible massive planet far beyond Pluto. "It probably has collided with them over time", Sheppard said.

This moon, now called Valetudo, moves in a prograde motion, though it is slightly inclined compared to the orbits of the other moons. "Head-on collisions would quickly break apart and grind the objects down to dust."Some of Jupiter's moons and moon groupings, including the "oddball", could have formed from collisions like this, according to the statement". We already have a classification for dwarf planets.

And that raises a question: Does an object less than a mile across deserve to be called a moon?

Depending on what survives from any such collision, Jupiter may then have even more moons. Its small size backs that up. Sheppard added that his team performed similar moon searches at Uranus and Neptune - but came up empty.

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