Ten newly found moons of Jupiter include a 'wrong-way driver'

Federico Mansilla
Julio 17, 2018

With a total of 79 moons, Jupiter is now the most lunar-rich planet in the solar system. To check whether this could have happened, the researchers are working on supercomputer simulations of these orbits to calculate how many times an object with Valetudo's orbit could have collided with the retrograde moons in the solar system's lifetime.

Using the Blanco four-metre telescope at Cerro Tololo Inter-American in Chile - which had been recently fitted with a new and highly sensitive instrument called the "Dark Energy Camera", which is about the size of a small vehicle - they detected objects that seemed to be moving against the background stars.

But the last moon is a weird one. Each takes about two years to circle the planet. "It's also likely Jupiter's smallest known moon, being less than one kilometre (0.62 miles) in diameter". Some slipped in and out of view, complicating the task.

This twelfth moon has a wide, 1.5-Earth-year orbit around Jupiter and travels among the retrograde moons. Galileo discovered the first four of Jupiter's moons, all huge, in 1610. It takes them about two Earth years to orbit the planet. Researchers have proposed naming the "oddball" Valetudo, after the Roman goddess of health and hygiene.

Jupiter's orbital family has just rapidly expanded, with scientists today announcing the discovery of 10 new miniature moons around the gas giant.

These two groups of prograde and retrograde moons consist of "irregular" satellites, or moons whose orbits have irregular, or noncircular, shapes. It's out where the outer, retrograde moons are, but it's orbiting Jupiter in the prograde direction, driving into the oncoming traffic. They had set their sights on the outer solar system and were looking for more evidence of the elusive Planet Nine, a predicted but as yet unobserved large outer solar system planet.

The chance find brings Jupiter's tally of moons to 79, 17 more than Saturn, the planet with the second most. Lines point to Valetudo, the newly discovered "oddball" moon.

More news: Astronomers find 12 new moons orbiting Jupiter, including an "oddball"

"There was no eureka moment", said Sheppard, who led the team of astronomers.

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

Scientists were looking for objects on the fringes of the solar system previous year when they pointed their telescopes close to Jupiter's backyard, according to Scott Sheppard of the Carnegie Institute for Science in Washington. Some of the outer moons, on the other hand, are retrograde moons, which orbit in the opposite direction. Not yet, anyway. "Right now the only definition of a moon is something that orbits the planet", Sheppard said, as long as it isn't human-made. This means it crosses paths with the outer retrograde moons and could collide with them. "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".

The realm of the giant planets - between Jupiter, Saturn, Uranus and Neptune - is largely devoid of small objects.

For example, the discovery that the smallest moons in Jupiter's various orbital groups are still abundant suggests the collisions that created them occurred after the era of planet formation.

The moons had not been spotted before because they are tiny. "Maybe a dwarf moon for anything that's 1 kilometer in size of smaller", he says.

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