Astronomers find 62 new moons of Saturn, bringing the total to 145
Saturn has reclaimed the title of "moon king" following the discovery of 62 new moons. In February 2023, the gas giant Jupiter surpassed Saturn when 12 new Jovian moons were discovered orbiting it, bringing the total to 95.
The ringed planet now has a total of 145 moons, as officially recognized by the International Astronomical Union. Saturn is the only planet in the solar system, with over 100 natural satellites orbiting it.
The new moons were discovered by collaborating institutes led by Edward Ashton, a postdoctoral fellow at the Academia Sinica Institute of Astronomy and Astrophysics.
How were the moons discovered?
The team used the "shift and stack" technique to look for smaller, fainter moons around Saturn that might have gone unnoticed in a single photo. This technique uses a series of images that shift at the same rate as the moon moves across the sky.
The official release from the University of British Colombia explained: “Shifting a set of sequential images at the rate that the moon is moving across the sky results in enhancement of the moon's signal when all the data is combined, allowing moons that were too faint to be seen in individual images to become visible in the `stacked' image.”
Astronomers were able to detect moons as small as 1.6 miles (2.5 kilometers) in diameter around Saturn using this sharp imaging technique.
However, confirming these moons usually takes years. This is because astronomers need to meticulously examine the images and track the spotted objects for years using telescopes to confirm that it is indeed a moon and not simply a space rock orbiting the planet.
"Tracking these moons makes me recall playing the kid's game Dot-to-Dot because we have to connect the various appearances of these moons in our data with a viable orbit,” Edward Ashton said in an official statement. But there’s a catch. “With about 100 different games on the same page, and you don't know which dot belongs to which puzzle," added Ashton.
This is the first time astronomers have used this method to look for Saturnian moons. This method was previously used to detect the moons of the ice giants Neptune and Uranus. The Canada-France-Hawaii Telescope (CFHT) on Mauna Kea in Hawaii was used to collect data for this technique between 2019 and 2021.
The team announced the discovery of one of the moons, designated S/2019 S 1, in 2021, while the rest were announced in recent weeks.
Classified as “irregular moons”
All of the newly discovered moons fall into the irregular moon category. The number of irregular moons orbiting Saturn has reached 121, with 24 known regular moons.
The moons in this category are distinguished by "large, elliptical, and inclined orbits" in comparison to the orbits of regular moons.
According to the official release, these types of moons tend to clump together in groups regarding the tilt of their orbits. Saturn's system has three distinct groups: the Inuit, the Gallic, and the Norse. The majority of these moons belong to the Norse group.
"As one pushes to the limit of modern telescopes, we are finding increasing evidence that a moderate-sized moon orbiting backward around Saturn was blown apart something like 100 million years ago," said Professor Brett Gladman at the University of British Columbia in the release.
Some millions of years ago, the larger moons in this gas giant’s system may have slammed into each other. This massive collision created remnants of smaller moons dispersed into different orbits, forming groups around Saturn.
According to astronomers, close examination of these irregular moon groups could help us learn more about the collisional history of the Saturn system.
The scientific community hopes that NASA's Dragonfly mission, which is expected to launch in 2027, will be able to collect data and images of Saturn's small outer moons.