Saturn surpasses Jupiter as 'moon king'

The new discoveries bring Saturn’s total number of moons to 82, surpassing the 79 that are known to orbit Jupiter.

Scott S Sheppard, astronomer at the Carnegie Science and leader of the team that made the discovery, said: "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.

“The new moons are very faint, requiring some of the largest telescopes in the world to find them.”

Of the 20 newly-discovered moons, 17 orbit the planet in retrograde. Of the remaining three prograde moons, the two that are closest to the planet take about two years to travel once around Saturn. The more distant retrograde moons and the remaining prograde moon each take more than three years to complete an orbit.

One of the newly discovered retrograde moons is the furthest of all the known 82 moons around Saturn. It orbits Saturn at an average distance of 26,676 gigametres.

The new moons were discovered using the Subaru telescope on Mauna Kea in Hawaii. Professor Sheppard told Laboratory News that moons around Saturn at about the 3-mile size range have likely all been discovered.

“To find smaller moons will likely require the next generation of telescopes being built, like the Giant Magellan Telescope in Chile.  

"We believe there are about 100 moons around Saturn bigger than 1 mile in size, but future larger telescopes will be needed to find these smaller and thus fainter moons.”

Carnegie Institution for Science has now opened a contest for the public to name the 20 new discoveries.

A similar contest was opened last year when Professor Sheppard announced the discovery of an additional 12 moons orbiting Jupiter, bringing the planet’s total to 79. Five were christened by members of the public as Pandia, Ersa, Eirene, Philophrosyne and Eupheme.