Published: Fri, July 20, 2018
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One of Jupiter's Newly Discovered Moons Is Doing Something Really Weird

One of Jupiter's Newly Discovered Moons Is Doing Something Really Weird

Putting out the trash a day early, playing loud music at all hours, never getting around to fixing that fence. While the team did discover 12 new moons, two were announced a year ago.

One of these new moons turned out to be a bit of a rebel.

The worst-case scenario for Valetudo?

"This is an unstable situation", said Dr Scott Sheppard from the Carnegie Institution for Science team. "It's going to slap into something". Even though these are objects in our own solar system, the observations were challenging.

Turns out Jupiter has 12 extra moons we didn't know about.

If Planet Nine exists, it could be the runt of the giant planets, Sheppard said. 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.

Using the Blanco 4-meter telescope at Cerro Tololo Inter-American in Chile, with its highly-sensitive Dark Energy Camera, however, gave the team a distinct advantage. These satellites are part of a large group of moons that orbit in retrograde far from Jupiter.

Sheppard said these moons were probably objects that formed near Jupiter during the early days of the solar system and were "captured" by the planet's strong gravitational pull. Sheppard thinks it may be all that's left of a larger moon that crashed into one or more of the retrograde moons sometime in the past.

They would be able to tell the difference between Jupiter and the objects around it versus the distant solar system objects because any objects around Jupiter would be moving at the same rate as the gas giant. Sheppard expects there could be even more small moons lurking out there. Two of the newly discovered moons, the ones closest to Jupiter, have prograde orbits, too.

As a whole they're not so unusual or remarkable, except, perhaps, for that rogue, Valetudo.


The recently discovered new Jovian moons are tiny, the maximum size in diameter being 2 miles.

In addition to these two groups, Jupiter has "regular" satellites, or moons with almost circular orbits.

So we are still finding moons for Jupiter.

Galileo detected Jupiter's four largest moons, Io, Europa, Ganymede and Callisto in 1610. The observations were made in 2017, but it took a year to track them long enough to nail down their orbits. Though it has a prograde orbit, it lives among a group of retrograde moons, meaning it careens across their orbits every once in awhile. Further out, there are nine moons that are spinning in the opposite direction. While Earth only has one moon, and some planets, like Mercury and Venus, have none, others have dozens, namely Jupiter and Saturn.

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

"We're looking for new possible planets and dwarf planets in our solar system, just seeing what is out there", Sheppard said.

But the discovery might be short-lived because Valetudo faces destruction in head-on collisions.

The moon we see today is the remainder of a much bigger world that blew apart after the crashes.

The study was published in the International Astronomical Union Minor Planet Electronic Circular.

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