Astronomers keep finding new moons of Jupiter and Saturn

A multitude of new moons have made their presence known around Jupiter and Saturn, bringing their population of moons to 101 and 285, respectively.

The new discoveries also bring the total number of known moons orbiting planets and dwarf planets in the solar system to 442 — and that's not including the many moonlets accompanying various asteroids or small Kuiper Belt objects.

The newly found moons — four for Jupiter and 11 for Saturn — were announced by the Minor Planet Center, which is the clearing house for astronomical discoveries of asteroids, comets, centaurs and, indeed, moons.

None of the newly discovered moons are very large, averaging about 1.9 miles (3 kilometers) in diameter. They have very wide orbits, far wider than the larger moons of Jupiter and Saturn, and are exceedingly faint, between magnitude 25 and 27. (For context, our moon sits at magnitude -12.6.) This puts them well beyond the range of backyard telescopes.

Instead, it took intense observations from some of our largest ground-based telescopes to snag them. The four new moons of Jupiter were all found by astronomers Scott Sheppard of the Carnegie Institution for Science and David Tholen of the University of Hawaii, using the 6.5 meter Magellan–Baade telescope at Las Campanas Observatory in Chile and the 8-meter Subaru telescope atop Mauna Kea in Hawaii.

Meanwhile, the 11 new moons of Saturn were uncovered thanks to a team led by Edward Ashton at the Academia Sinica Institute of Astronomy and Astrophysics in Taiwan. They used the 3.5-meter Canada–France–Hawaii Telescope on Mauna Kea. This comes after Ashton led a team to discover 128 new moons of Saturn as recently as 2025.

Both Sheppard and Ashton in particular are prodigious discoverers of moons in the solar system, with over 200 each to their name, many of them being co-discoveries.

While Jupiter is lagging behind Saturn in the moon stakes by quite a large number, Europa Clipper and the Jupiter Icy Moons Explorer (JUICE) missions, currently heading to Jupiter, could redress the balance when they arrive in the Jovian system in the early 2030s.

To summarize, the current tally is that for the planets, Earth has one moon, Mars has two, Jupiter has 101, Saturn has 285, Uranus has 28 and Neptune has 16 while Venus and Mercury have none. For the dwarf planets, Pluto has five, Eris has one, Makemake has one, Haumea has two and Ceres has none.

The new moons of Jupiter were announced in Minor Planet Electronic Circulars MPEC 2026-F09, F10, F11 and F12, and the 11 new moons of Saturn were declared in MPEC 2026-F14.