Prior to these new discoveries, Saturn had 83 moons officially recognized by the International Astronomical Union (IAU). Currently, that number has increased to 145, as reported by Space on May 12. This milestone marks a significant achievement for Saturn, making it the first celestial body in the universe known to have over 100 moons in orbit.
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Image of Saturn taken by the Hubble Space Telescope in June 2018. Photo credit: NASA/ESA/A. Simon (GSFC)/OPAL Team/J. DePasquale (STScI)
Edward Ashton, a postdoctoral researcher at the Institute of Astronomy and Astrophysics at Academia Sinica, along with colleagues, made these new moon discoveries using the technique of “shifting and stacking.” This technique involves capturing a series of motion images at the same speed as the moon’s movement across the sky, enhancing the signals from the moons. Consequently, previously unseen moons, too faint to be visible in individual images, can be revealed through the “stacked images.”
Astronomers have applied this method to search for moons around giant icy planets such as Neptune and Uranus, but this is the first time it has been used for the second-largest planet in the Solar System, Saturn.
In their recent study, the team of experts utilized data collected from 2019 to 2021 by the Canada-France-Hawaii Telescope (CFHT) atop Maunakea in Hawaii. This data enabled them to identify moons around Saturn with diameters as small as 2.5 kilometers.
Although some moons were observed earlier in 2019, astronomers required additional information to confirm that they were indeed moons and not asteroids approaching Saturn. Therefore, they tracked these objects for several years to ensure they were truly orbiting this massive planet.
The newly discovered moons are classified as “irregular moons.” This term refers to objects that are influenced by the gravitational pull of a planet and orbit it in larger, flatter, or more inclined elliptical orbits compared to regular moons. Saturn now has 121 irregular moons and 24 regular moons.
In February, Jupiter surpassed Saturn to claim the title of the “Moon King” with the confirmation of 12 new moons, bringing the total to 92. However, Saturn now reclaims the crown with its 145 moons. Nevertheless, this title may continue to change hands as astronomical technology for moon detection continues to advance.