Saturn beats Jupiter with 82 moons, including 20 just discovered

Saturn has broken a new solar system record with the discovery of 20 new moons circling it.

The ringed planet is now has 82 known moons, smashing the previous record held by Jupiter, which has 79, reported the Carnegie Institution for Science Monday. 

In fact, Jupiter has held the “moon king” title for decades, and got a dozen new moons added to its tally just last year, says Scott Sheppard, the Carnegie astronomer who led the new discoveries.

“Saturn has just surpassed it for the first time today,” he added. “I think these moons are exciting because they tell us about the planet formation process.”

In fact, astronomers believe that Saturn’s smaller moons are the “last remnants” of the objects that originally came together to form the giant planets.

These are the orbits of 20 new moons found around Saturn. The ones marked in blue are part of the Inuit group. The green one is part of the Norse group. (Carnegie Science)

The new moons are all about five kilometres in diameter. They were first spotted in 2004 using the Subaru telescope on Mauna Kea, a dormant volcano in Hawaii that’s home to many large telescopes. But it took 10 years of improvements to computer power and algorithms to derive their orbits from the data and link their positions from year to year.

The data and calculations were submitted to the Minor Planet Centre of the International Astronomical Union, the scientific organization that assigns names to celestial bodies, which confirmed they are new moons. 

It invited the public to propose official names for the moons, which are currently identified by a series of letters and numbers. Suggestions can be tweeted to @SaturnLunacy with the hashtag #NameSaturnsMoons. Nominators are invited to explain why they picked the name, and “photos, artwork, and videos are strongly encouraged.” 

Two of the moons are part of a group of moons called the Inuit group, whose original members were discovered by Canadian astronomers and named by team member John Kavelaars, currently at the Dominion Astrophysical Observatory in Victoria, and Inuit storyteller and children’s author Michael Arvaarluk Kusugak. The two new moons, will be given names from Inuit mythology. All the moons in the group (the ones named already are Ijiraq, Kiviuq, Paaliaq, Siarnaq and Tarqeq) orbit at an angle to Saturn’s orbit and are thought to have originally been part of a single object about 40 kilometres wide that broke into fragments.

A third moon is part of a similar group called the Norse group that will be given names from Norse mythology.

The other 17 new moons are retrograde moons — unlike the Inuit and Norse moons, they travel in the opposite direction to Saturn’s rotation.

A number of other potential Saturn moons spotted in 2004 have not been confirmed as moons yet.

Sheppard says he thinks Saturn probably has 100 moons that are a kilometre in size or bigger, but astronomers may need to wait for the next generation of bigger, better telescopes to confirm them all. On average, Saturn’s known moons are bigger than Jupiter’s, he added. “But since Saturn’s further away, it’s harder to detect its moons.”