The Hunt for 'Planet Nine' Discovers 12 New Moons Around Jupiter

Mindy Sparks
July 18, 2018

The announcement of the new moons was published Tuesday in the International Astronomical Union Minor Planet Electronic Circular. Sheppard's discovery brought the total number of objects orbiting Jupiter to 79 - but he said one discovery stood out in particular.

Because of how many observations it takes to determine an object in space is actually in orbit around Jupiter, it took about a year to confirm that these were, indeed, new Jovian moons.

The researchers believe that there might be a planet 200 times farther from the sun than we are (and five times more distant than Pluto) with an extremely stretched and oblong orbit on the edge of our solar system. Telescopes in Chile, Hawaii and Arizona were used for the discovery and confirmation. They take less than a year to orbit Jupiter.

Nine of the newly discovered moons have retrograde orbits, meaning that they orbit in the opposite direction of the planet's spin.

Scientists have discovered 12 previously unknown moons orbiting Jupiter, and one of them is a real oddball. 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. 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. By this latest count, our solar system's largest planet now has 79 moons, more than any other.

The team also discovered one particularly odd moon in the new batch.

Europa, one of Jupiter's larger moons, casts a shadow on the planet's surface. It orbits Jupiter in and amongst where the retrograde moons reside, however, it follows a highly risky prograde orbit as it does so.

Finding a moon that tiny, he noted, means it must have formed after all the gas and dust had cleared.


Sheppard is leading a team that scrutinizes the darkest reaches of the solar system. The work was led by Scott Sheppard, a researcher at the Carnegie Institution for Science who studies small bodies in the solar system and the formation of planets and stars.

Astronomers group Jupiter's moons by their distance from the planet as well as their orbital direction. Maybe 100 or more of the really small ones.

Two other new moons are closer and move in a prograde orbit, which is in line with the direction that Jupiter is moving.

"This simulation takes a few months to run and we expect the answer is between about 100 million years and 1 billion years, which is long in human time but not all that long in astronomical time", Sheppard said.

The astronomers were not intentionally searching for new Jovian moons when they began observing.

Nine of the moons are part of an outer "swarm" that orbit in the opposite, or retrograde, direction of Jupiter's spin, taking about two years to complete one trip around the planet.

Astronomers suspect that the retrograde moons may be the remains of larger moons that were destroyed in head-on collisions with prograde objects. Because of that small moon's orbit, it may be eventually be destined for an crash.

Valetudo is something of an oddball. Because they formed between the two belts, the moons are probably composed of rock and ice. "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".

Other reports by Iphone Fresh

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