20 More Moons Found Around Saturn
By: James Maynard
Tags: Solar System, Science, Planets, Space, Astronomy

With the discovery of 20 more moons, Saturn now holds the record for the greatest number of moons anywhere in the Solar System, and you can help name them!

The discovery of 20 previously-unknown moons around Saturn brings the number of known moons orbiting that planet up to 82. This surpasses Jupiter, with 79 moons currently known to orbit that world. In an effort to name these worlds, the International Astronomical Union (IAU), which assigns official names to bodies in space, is asking the public to help them choose names for these newly-discovered worlds.

The newly-discovered moons each have diameters around five kilometers (three miles). Seventeen of the 20 newly-discovered Saturnian satellites orbit in a retrograde orbit (in the same direction that Saturn rotates). Three of the worlds revolve around Saturn in the more-common prograde direction. Two of those three moons take less than two years to complete one orbit of the ringed planet, while the third prograde body, as well as the retrograde moons (which orbit further from Saturn), take more than three years to complete one orbit. One of these retrograde moons is the most distant known satellite in Saturn’s system.

The orbits of the 20 newly-discovered moons of Saturn are shown here. Image credit: NASA/JPL-Caltech/Space Science Institute. Starry background courtesy of Paolo Sartorio/Shutterstock

“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,” Scott S. Sheppard of Carnegie Science explains.

The orbits of the moons of Saturn, seen from above the system. Image credit: Carnegie Science

Seen from the side, the angles of the orbits appear like pick-up-sticks. Image credit: Carnegie Science

The outer moons of Saturn are bound together into three loose clusters, and each of these newly-discovered moons is associated with one of these groupings. This pattern suggests the tiny moons may have formed from the destruction of other, larger, bodies in the distant past.

The orbital path followed by one of these outer groups, the Inuit, is angled at more than 45 degrees from the angle where most of Saturn’s moons are found, while the Gallic group orbits at a 36-degree angle.

“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,” Sheppard described.

Just as the planets of the Solar System coalesced from cloud of gas and dust, planetary science suggests a similar process occurred around Saturn billions of years ago.

The new moons were discovered using the Subaru telescope, located on Mauna Kea in Hawaii.

A look at what we know — so far — about these newly-recognized worlds orbiting Saturn. Video credit: Lunartic (CC)

“The scientific theory I like best is that the rings of Saturn are composed entirely of lost airline luggage.” — Mark Russell

Sheppard and his team discovered 12 moons around Jupiter in 2018, and Carnegie Science held a contest to name five of the bodies. This time, the public is asked to, once again, weigh in on finding names for some of these diminutive moons.

Unfortunately, Moony Moon McMoonface is out of the running, as names must come from one of giants from Norse, Gallic, or Inuit mythology. Submissions must adhere to several other rules, detailed on the Carnegie Science website.