Astronomers from the Harvard-Smithsonian Center for Astrophysics have announced the discovery of 128 previously unidentified “irregular” moons orbiting Saturn, bringing the gas giant’s total to 274. The team behind the historic discovery suspects many of the newly discovered Saturnian moons are relatively young, with some having been captured by Saturn’s gravity as recently as 100 million years ago.
According to Mike Alexander, one of the authors of a paper announcing the discovery, this is the single largest batch of new moons ever discovered. Dr. Alexandersen also noted that naming the newly discovered moons will fall upon the study’s lead author, Edward Ashton of Taiwan’s Academia Sinica Institute of Astronomy and Astrophysics.
“Whoever discovers them gets the right to name them,” Alexandersen said.
The astronomer also pointed out that the current limitation of naming Saturn’s moons after characters from Norse and other mythologies may be tested, given the sheer number of new moons in the latest haul.
“Maybe at some point, they’ll have to expand the naming scheme further,” he added.
Irregular Moons of Saturn Join a Long List of Tantalizing Targets
Saturn has long fascinated astronomers due to its myriad moons, including the possibility that the planet and its rings may be titled due to an event with an ancient missing moon. Several studies have suggested that Titan may host life below its frozen methane lakes. The liquid lakes on Titan are also the only liquid bodies in the solar system besides Earth. One study found they may even behave similarly to waves on Earth’s lakes.
Titan
(NASA/JPL/Space Science Institute)
The frozen moon Enceladus is also a target for life-hunting astrobiologists. One recent study found the presence of phosphates in the massive plumes of seawater erupting from Enceladus. Saturn’s moon Mimas, which bears an odd resemblance to the Death Star from Star Wars, has also fascinated scientists for its potential to host life beneath its icy shell.
Mimas
In this view captured by NASA’s Cassini spacecraft on its closest-ever flyby of Saturn’s moon Mimas, large Herschel Crater dominates Mimas, making the moon look like the Death Star in the movie “Star Wars.” IMage Credit: NASA/JPL-Caltech/Space Science Institute.
Several missions have been proposed to perform a close-up analysis of Saturn and its moons. NASA’s Dragonfly mission aims for a 2028 launch to study Titan up close following its 2034 arrival. A more unorthodox proposal suggests using morphing aerial robots to study the solar system, starting with Titan.
The newest discovery of 128 new moons orbiting Saturn will likely add to that list, increasing the list of future targets for exploration.
Long Orbits and Extreme Orbital Angles
Unlike Earth’s lone moon which is over 2,000 miles across, the newly discovered Saturnian moons are mostly only a few miles across. Still, according to the International Astronomical Union, which ratified the new moons on March 10th, if an object has a trackable orbit around its host, in this case, Saturn, astronomers classify it as a moon.
“You need to be able to prove that the object is in orbit around the planet,” said Dr. Ashton.
The 128 moons were discovered in 2023 using the Canada France Hawaii Telescope at Mauna Kea in Hawaii during observations made in 2023. Notably, Dr. Ashton was the lead researcher on the team that discovered 62 new moons orbiting Saturn that same year.
Saturn irregular moons
The Canada-France-Hawaii Telescope. Image Credit cfht.hawaii.edu.
While some moons have relatively regular orbits, like Saturn’s largest moon, Titan, the newly discovered objects are described as “irregular.” This classification means they are tiny relative to the planet’s other moons and orbit at an extreme angle compared to Saturn’s equator. These irregular moons often travel around their host planet in the opposite direction of typical moons.
According to the study authors, the newly discovered moons’ orbits are relatively far from the planet. For example, Saturn’s signature rings orbit about 175,000 miles above the planet’s surface, while Titan and Enceladus orbit roughly two million miles away. The orbits of the newly discovered moons range from 6.5 million to almost 18 million miles.
Notably, the objects may have several different origins. In some cases, the newly discovered moons may comprise portions of early Saturnian moons that smashed together to create smaller objects. The moons may also come from other planets or space objects that crashed together and were subsequently captured by Saturn as they passed by.
Space junk
The study authors are currently attempting to classify the moons into “families” that may have originated from the same collision to determine their origins.
“You’re trying to conclude what the great-great-grandparents were like, five generations later,” said Brett Gladman, an author of the paper at the University of British Columbia.
One subgroup that grabbed the team’s attention consists of 47 of the 128 newly discovered moons. Named after the Norse deity Mundilfari, this group may all come from a collision in Saturn’s orbit as recently as 100 million years ago. Astronomers note that this is relatively recent, cosmologically speaking, given that the approximate age of the solar system is over 4 billion years. If correct, this date would go against the generally accepted belief that this region of the solar system has remained relatively calm during the last 100 million years.
James Webb Space Telescope Could Reveal More Details
Astronomers hoping to learn more about these individual moons may have to wait for time on the more sensitive observatories like the James Webb Space Telescope.
There may also be thousands of similarly irregular moons in Saturn’s orbit waiting to be discovered. Aston says he may leave the discovery of those moons to other astronomers who could bring a fresh perspective to the effort.
“I’m a bit mooned out at the moment,” he quipped.
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him onX,learn about his books atplainfiction.com, or email him directly atchristopher@thedebrief.org.