Saturn Outshines Jupiter With Discovery Of 20 New Moons

James Marshall
October 9, 2019

The Carnegie Institution had a moon-naming contest for them; another is planned now for Saturn's new moons. These discoveries bring the planet's total moon count to 82, surpassing Jupiter for the most in our solar system.

The discovery was announced on Monday by the International Astronomical Union's Minor Planet Centre.

"Studying the orbits of these moons can reveal their origins, as well as information about the conditions surrounding Saturn at the time of its formation", institution's staff scientist Scott S. Sheppard said, according to the release.

The planet now has the most moons, surpassing Jupiter's 79 moons.

The new discovery brings Saturn's total up from 62 to 82 - the most in the solar system.

What is significant about Saturn's newly discovered moons?

Sheppard said Jupiter was the planet with most known moons since the late 1990s, according to BBC News.

Sheppard is no stranger to discovering natural satellites - he found 12 new moons orbiting Jupiter in 2018. Sheppard and his colleagues suspect there are 100 moons around Saturn larger than one mile in size, "but future larger telescopes will be needed to find these smaller and thus fainter moons".

According to the researchers, each of the newly discovered moons is about 3 miles (5 km) in diameter. Of the 20 new moons, three are in prograde orbit (moving in the same direction as Saturn's rotation) and 17 are in retrograde orbit (you guessed it, moving opposite Saturn's rotation).

How were Saturn's new moons discovered? Most of the other distant new moons take about three years to complete on orbit. One of the newly discovered retrograde moons is the farthest known moon around Saturn.

One particularly interesting note about the newly-discovered moons is that 17 of them orbit Saturn "backwards". Image: Saturn image is courtesy of NASA/JPL-Caltech/Space Science Institute.

Another three have prograde orbits, meaning they orbit in the same direction as the planet's spin. The moons must be named after giants from Norse, Gallic, or Inuit mythology. In many ways, Earth's moon is the ideal introduction to teach humanity some very basic things about how the universe works. All name submissions for this group must be giants from Norse mythology.

This kind of grouping of outer moons is also seen around Jupiter, indicating violent collisions occurred between moons in the Saturnian system or with outside objects such as passing asteroids or comets.
Seeing that Saturn "has more moons even though it is harder to find them, shows just how many moons Saturn has collected over time", Sheppard told Gizmodo. It is believed that a similar gas-and-dust disk surrounded Saturn during its formation.

While it's cool to catalogue all the moons orbiting Saturn, finding these relatively tiny rock nuggets also helps researchers understand the formation of the planets in the solar system.

If you discovered a moon, what would you name it? The other three circle in the same direction that Saturn rotates.

Welcome, new moons! We look forward to learning more about you.

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