Saturn runs rings around Jupiter

Ratification of 128 additional moons puts the smaller gas giant way ahead on satellite count

The International Astronomical Union on Tuesday ratified the recent discovery of 128 previously unknown moons orbiting Saturn, taking the gas giant’s count of known natural satellites to 274.

The ratification means Saturn goes well ahead of Jupiter, which has a puny population of 95 known moons.

The moons were discovered by a team of astronomers who in 2023 used the Canada France Hawaii Telescope at Mauna Kea in Hawaii to observe Saturn.

We know almost nothing about the newly discovered moons because they’re small, distant, and probably not much more than rocks.

All have irregular orbits at steep angles compared to Saturn’s equator and are found beyond the planet’s famous rings and well outside the orbits occupied by its major moons.

The scientists who spotted the moons named a 47-strong group “Mundilfari” and apparently speculate they may have been the result of a collision in near-Saturn space that took place as recently as 100 million years ago.

That’s too early to have killed the dinosaurs by at least 30 million years.

Nature reports that the discoveries were made possible by a combo of more time using the telescope, and techniques that allow captured images to be stitched together. Those techniques were used to find 62 Saturnian moons in 2023 before again being pressed into service for this new set of discoveries.

The International Astronomical Union ratified the moons on Tuesday with three formal documents - one describing thirty-three moons, another detailing thirty-four and the last listing 61 satellites.

They’re dense but fascinating documents that list all of the observations during which the satellites were spotted. The document describing 33 moons has 844 lines of observation data!

The documents also include a section detailing each moon’s orbit.

The moons don’t have names, and the honor of picking them apparently falls to Edward Ashton, a postdoc fellow at the Academia Sinica Institute of Astronomy and Astrophysics in Taiwan. Ashton is also lead author of a forthcoming paper describing the newly discovered moons, which will soon appear in Research Notes of the American Astronomical Society. ®