The Tartan

By Sage Rohrbach

Saturn may be one of the most popular planets, commonly known for its enormous size and prominent rings. Recently, however, public attention has been shifting from Saturn’s picturesque facade to the recognition of its many moons. 

On Tuesday, March 11, 2025, 128 new moons were recognized by the International Astronomical Union, bringing Saturn to an impressive total of 274 moons. That number is more moons than all seven of the other planets in our solar system combined. While this discovery may surprise some, it serves as supporting evidence for events hypothesized to have occurred around Saturn approximately 100 million years ago. 

Scientists and researchers theorize that 100 million years ago — relatively recently in astronomical time — a larger moon may have collided with another moon or a comet passing Saturn, resulting in a large amount of debris. That long-ago collision would explain the formation of Saturn’s rings as well as the many medium-sized moons that orbit the planet. In particular, this hypothesis could explain the major mystery of why many of Saturn’s moons seem to orbit in an irregular retrograde manner, moving the opposite direction of Saturn’s rotation. 

The direction in which moons orbit is determined by their formation history. Regular moons, such as Saturn’s Titan and Rhea, form within the planet’s protoplanetary disk, a swirling cloud of gas and dust that surrounds a young star upon its formation. The disk’s rotation dictates the new planet’s directional revolving and results in the prograde orbits (an orbit where a celestial body revolves around its parent body) of any moons that form within it. Since all of Saturn’s 128 new moons move opposite of this prograde motion, however, they are not likely to have formed with Saturn, but rather as the result of this hypothesized collision. This would also explain the miniscule size of these moons, whose diameters average only a few miles compared to our own moon’s 2,159-mile diameter. 

This evidence for the collision hypothesis has brought one of Saturn’s moons, Enceladus, into light. Enceladus was previously recognized as a prime candidate for potential habitability, as it contains a global ocean under its icy crust as well as plumes of water and organic materials that erupt from its south pole. Because of the collision hypothesis, however, some have jumped to the conclusion that it is extremely unlikely that Enceladus has any life, assuming that it formed with the majority of the other moons 100 million years ago. Nonetheless, Enceladus is a relatively regular moon, orbiting Saturn in a mostly stable, prograde manner. Thus, the possibility of life should not be ruled out so soon. Despite many moons having formed more recently, Enceladus is one of Saturn’s only 24 out of 274 moons displaying regular motion. This presents evidence that Enceladus may have formed alongside our solar system 4.5 billion years ago, likely enough time for life to have formed. 

Although the true nature of Enceladus is still unknown, the discovery of Saturn’s new moons has led scientists to revisit what was previously thought about the planet, revitalizing interplanetary research and popularizing Saturn for yet another reason.