Astronomers have spotted 20 more moons orbiting Saturn, bringing the total number of Saturnian moons to 82, surpassing the 79 that are known to orbit Jupiter. The Guardian reports: The scientists discovered the moons when they set algorithms to work on decade-old images captured from the powerful Subaru telescope on Mauna Kea in Hawaii. By comparing images taken over hours and days, the algorithms distinguished between stationary stars and galaxies and moons that hurtled around the planet. Depending on the angle of approach, comets and asteroids straying too close to Saturn in the early solar system would have become locked into radically different orbits around the planet. Only three of the new moons have so-called prograde orbits, meaning they circle Saturn in the same direction that it rotates. The other 17 are in retrograde orbits, meaning they orbit the planet backwards. One is the most distant moon ever spotted from the planet.

The outer moons of Saturn fall into three broad families according to how they orbit the gas giant. Two of the new prograde moons appear to belong to a group that swings around Saturn at an angle of about 46 degrees. The moons, named after Inuit mythology, may once have belonged to one far larger moon that broke apart in the distant past. The new retrograde moons appear to belong to another group named after Norse mythology and are also thought to be fragments of a much bigger parent moon that was smashed to pieces in the solar system’s violent past.