Most moons for a planet
Who
Saturn
What
83 total number
Where
Not Applicable ()
When

The planet with the greatest number of moons is Saturn, with 83. Following the discovery of 20 new moons orbiting Saturn in 2019, it overtook Jupiter’s total of 80 known moons. The most recent discovery in Saturn's orbit is S/2019 S1, which was found by a team led by Edward Ashton using the Canada–France–Hawaii Telescope, in Hawaii, USA, and announced on 16 November 2021.


Solar system planets have "numbered moons", which are unambiguously confirmed to exist, and "provisionally designated moons", which are awaiting their name and number. Of the provisional moons, some are only tentative discoveries, which have less than a year's worth of observations to vouch for their existence. Saturn has 53 numbered moons, and another 30 that are awaiting final confirmation. Jupiter, meanwhile, has 72 numbered moons and eight tentatively discovered moons.

All of the recently discovered moons are less than 5 km (3.1 miles) across, and orbit the planet at distances greater than 23.23 million km (14,435,260 miles). With the exception of the far-flung moon Phoebe, all of Saturn's major moons orbit within 3.5 million km (2.17 million miles) of the planet.

Most of the newly discovered moons sit in the retrograde group, also known as the Norse Group, which includes Pheobe. These moons orbit Saturn in the opposite direction to the planet's rotation, except for one of the newly discovered satellites, S/2004 S24, which has an prograde orbit. It is thought that this new discovery represents the last survivor of a group of moons that have long-since been destroyed.

Both Saturn and Jupiter likely have many more moons that are still to be detected, so this contest – which is not really a contest – is far from over. Given its greater mass and consequently larger gravitational sphere of influence, Jupiter probably has more moons overall.