Jupiter's moon count reaches 79, including tiny 'oddball'

Posted July 19, 2018

Along with two found through the same research project but announced in June 2017, this brings the roster of Jupiter's known natural satellites to 79. Sheppard, who is broadly interested in the formation of solar systems and has been involved in the discovery of 48 of Jupiter's known moons, realized this was the flawless opportunity to advance two separate research goals with the same telescope data.

"Jupiter just happened to be in the sky near the search fields where we were looking for extremely distant solar system objects, " Sheppard said, according to a Carnegie Institution news release.

Telescopes in Chile, Hawaii and Arizona were used for the latest discovery and confirmation. Sheppard said Jupiter and Saturn may actually have a similar number of moons, with some of Saturn's smaller ones not yet detected.

The tiny moon's orbit takes it both inside and outside of where the other new moons orbit, putting it at a high risk of colliding with them.

Our solar system is already teaming with almost 200 moons, and we just got 12 more to add to the list.

Sheppard, whose report appears in the International Astronomical Union Minor Planet Electronic Circular, suspects that Valetudo is the final remnant of a once much larger moon that has been ground to dust by collisions in the past. The moon, tentatively named Valetudo, also has a more inclined orbit than other prograde moons and is one of the smallest moons of Jupiter discovered to date, measuring less than 1 kilometer in diameter.

Nine of the new moons are part of a distant swarm of moons that orbit Jupiter in the opposite direction of its spin rotation.

"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. It's believed that numerous tiny moons around Jupiter were once much larger, having broken up over time due to the stress of gravity or perhaps even collisions with each other, resulting in the smaller objects we see today. "What these other objects were has been a mystery".

They said the space rocks were created when three larger bodies that once orbited the planet were obliterated into smaller chunks by collisions with asteroids.

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Two of them are pretty straightforward. Nine of them have retrograde orbits, going in the opposite direction to Jupiter's spin.

But the last moon is a weird one.

"These two newly discovered moons take a little less than a year to travel around Jupiter".

It also "has an orbit like no other known Jovian moon" and is "likely Jupiter's smallest known moon", he added. As such, the orbit crosses those of the more distant retrograde moons, raising the possibility of a possible head-on collision at some point in the future.

This moon, now called Valetudo, moves in a prograde motion, though it is slightly inclined compared to the orbits of the other moons.

Jupiter has several different types of moons.

Our solar system's giant planet has been hiding something - or 12 things, really. TheyÂre calling one moon an ‘oddball because of its unusual orbit.

It has an angled prograde orbit that takes about a year and a half to complete.

"A full paper will likely be written after these simulations are done in a few months".

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