In 2023 Saturn hit 146 confirmed moons to Jupiter's 95 — the first planet ever known to pass 100, winning the tally by 51.
In 2023 Saturn's confirmed moon count reached 146 against Jupiter's 95, making it the first planet ever known to pass 100 moons.
By the end of May 2023, Saturn had won a race that Jupiter had long dominated. Its confirmed satellite count stood at 146 to Jupiter's 95 — a lead of exactly 51 moons, and the first time any planet was known to hold more than 100.
The tally is not folklore. Scott Sheppard and colleagues stated it plainly in a 2023 note for the *Research Notes of the AAS* (volume 7, article 100): "Jupiter now has 95 and Saturn 146 confirmed moons." Subtract, and Saturn leads by 51.
How Saturn overtook Jupiter
For decades Jupiter was the presumed champion, its family of moons the largest anyone had cataloged. The reversal came from a dedicated hunt for Saturn's *irregular* moons — small, distant bodies on tilted, often backward-looping orbits, likely captured fragments of larger objects that were shattered long ago rather than moons that formed neatly alongside the planet.
The team, which included Sheppard along with Edward Ashton and Brett Gladman, used the Canada-France-Hawaii Telescope on Maunakea. Finding these objects is grueling. An irregular moon a few kilometers across, orbiting tens of millions of miles from Saturn, is faint and slow-moving against a field of background stars. The astronomers took many images of the same patch of sky, then "shifted and stacked" them — digitally nudging each frame to follow a moon's predicted motion so that its light piles up into a detectable point while stars smear into streaks. Confirming a single moon can take years of repeat observations to pin down its orbit before the International Astronomical Union's Minor Planet Center will certify it.
As *Sky & Telescope* reported in 2023, this campaign turned up 62 new moons, pushing Saturn to 145 and breaking Jupiter's 95-moon record. *EarthSky* covered the same milestone, noting that the haul made Saturn the first planet known to exceed 100 satellites. The 146th, catalogued as S/2006 S 20, was confirmed by the Minor Planet Center on May 22, 2023 — the figure NASA's National Space Science Data Center later lists on its Saturnian Satellite Fact Sheet as "previously confirmed."
Why "moon" is a slippery word
The vivid detail here is how small these objects really are. Many of the 62 new finds measure roughly 2.5 kilometers across — barely the length of a modest city. They cluster into "dynamical families" whose orbits echo one another, which is exactly what Sheppard's team argued in their title: these groupings suggest the fragments descend from a handful of larger parent bodies that collided and broke apart. Saturn, in other words, is orbited by the debris of ancient wrecks.
That raises the question the record can't quite settle: what counts as a moon? There is no official size floor. A 2.5-kilometer chip of rock and a body like Titan — larger than the planet Mercury — both get the same word. The count is a function of how hard you look and how good your telescope is, not of any fixed natural line between "moon" and "orbiting rubble."
Which is why the number keeps moving. In March 2025 astronomers announced another 128 Saturnian moons in a single batch, and NASA's fact sheet now treats 146 as the baseline before that surge. Jupiter's count will keep climbing too, as surveys sweep its neighborhood.
So Saturn's 51-moon lead as of 2023 is real, documented, and checkable — but it is also a snapshot of a contest that has no finish line. The true tally isn't the size of a planet's family. It's the size of our telescopes, and the patience of the people pointing them.