The International Astronomical Union’s Minor Planet Center (MPC) has confirmed the presence of 11 additional moons or natural satellites around Saturn, taking the total known Saturnian moons to 285. Four new satellites around Jupiter were announced on the same day, bringing the total number of known Jovian moons to 101. The MPC announced the discoveries in its latest electronic circulars.
The MPC is the international clearinghouse for positional measurements of asteroids, comets and the irregular satellites of the planets. The Center receives measurements from observers all over the world, and publishes the observations along with orbits, so that all measurements and orbits of all known objects are available from one centralised service. Most of the observations that led to the discovery of the new moons around Saturn were submitted within the past few months. The latest discoveries follow the announcements of 64 new moons in May 2023 and a further 128 in March 2025.
Details of the new moons
The 11 new moons around Saturn are likely around 1-2 km in diameter and around 100 million times fainter than anything visible to the naked eye. The moons have been given the following designations:
-
S/2020 S 45
- S/2020 S 46
- S/2020 S 47
- S/2020 S 48
- S/2023 S 51
- S/2023 S 52
- S/2023 S 53
- S/2023 S 54
- S/2023 S 55
- S/2023 S 56
- S/2023 S 57
The Jovian moons are designated as follows:
- S/2011 J 4
- S/2011 J 5
- S/2018 J 5
- S/2024 J 1
where,
- S - stands for natural satellite
- YEAR - year of the discovery observations; it is not necessarily the first observation, but an indication of the order in which the images were analysed or measurements received
- J or S - single letter denotes the planet (J for Jupiter, S for Saturn etc.)
- Number - counter used when multiple satellites are discovered in the same year
Discovery and validation
The Minor Planet Center operates at the Smithsonian Astrophysical Observatory in the United States, under the auspices of Division F of the International Astronomical Union. The Center is funded by a grant from the National Aeronautics and Space Administration (NASA).
To confirm the existence of a newly discovered moon, the MPC conducts a thorough check to ensure the observations do not correspond to any previously catalogued object. Subsequently, calculations are performed to determine the object's likely orbital path, confirming that a planetocentric orbit, an orbit around a planet, is more likely than a heliocentric orbit, an orbit around the Sun. Then the Center cross-references the new data against its catalogue to determine if any previous observations correspond to the newly observed object, thereby strengthening the confidence in the new discovery.
The new moons of Saturn were found by an international team led by Dr. Edward Ashton at the Academia Sinica Institute of Astronomy and Astrophysics. The four newly discovered moons of Jupiter were identified by Dr. Scott Sheppard.
Once their orbits are accurately determined, the MPC will assign these objects numerical designations, such as "Saturn CXXIII" (the planet name followed by a Roman numeral, this example corresponding to the 123rd satellite of Saturn). After this designation, the discoverer can propose official names. Following IAU naming rules, these satellites will receive names drawn from Gallic, Inuit, and Norse mythologies.
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