The collision that may have changed Saturn/ How were the moon "Titan" and the planet's rings created?

2026-02-24 22:32:00, Blog CNA

The collision that may have changed Saturn/ How were the moon "Titan"

Researchers have uncovered key insights about Saturn's mysterious and largest moon, Titan, including how it was formed.

Shrouded in a dense haze, Titan is about half the size of Earth and larger than Mercury—so much so that its gravitational pull causes Saturn to wobble and tilt. The moon, in turn, is moving away from Saturn at a rate of 11 centimeters per year, much faster than astronomers previously thought. The moon could be completely ejected from its orbit.

But Titan's shifting orbit is just one of many mysteries astronomers are trying to solve about Saturn and some of its 274 moons. Many of the questions have arisen from data collected by Cassini, a spacecraft that explored the Saturn system from 2004 to 2017.

New research has combined previous theories of Titan's formation, data from Cassini, and computer simulations to suggest a new origin story for Saturn's largest moon. The study was published this month on the open-access archive ArXiv and accepted for publication in The Planetary Science Journal.

“In this paper, I tried to put all of these things together and propose that about half a billion years ago there was an additional moon that collided with Titan, which actually became part of Titan,” said lead author Matija ?uk, a research scientist at the SETI Institute in Mountain View, California. SETI is a nonprofit organization that explores topics such as planetary science, the origins of life and extraterrestrial intelligence.

The study suggests that a lost moon collided with Titan, merging with it and changing the dynamics of the entire Saturn system. This collision may have also given birth to Hyperion, one of the strangest and most irregularly shaped moons.

The collision that may have changed Saturn/ How were the moon "Titan"

A false-color image of Saturn's moon Hyperion, taken during the Cassini flyby in September 2005.

An extra moon "explains everything"

Researchers found telltale signs of an ancient collision on Saturn's surface, which is made clear by its rings, which are tilted at an angle of 26.7 degrees compared to the plane in which it orbits the sun.

Before the Cassini mission, astronomers believed that gravitational perturbations caused by the orbit of neighboring Neptune caused Saturn to tilt over time.

Saturn's rings are tilted about 26.7 degrees relative to the planet's orbital plane.

However, Cassini data showed that the two planets are not exactly in sync, pointing to a missing element. In 2022, astronomers suggested that a lost moon, which they named Chrysalis, was a possible explanation for Saturn's current tilt. It once orbited the planet for billions of years, contributing to Saturn's resonance with Neptune, but about 160 million years ago the moon came too close to Saturn and broke apart in an event that created the planet's rings and changed its tilt.

In other words, the gravity and mass of the lost moon kept Saturn and Neptune in sync, and only its disappearance explains why they are now slightly disoriented.

If the collision also created Hyperion in its current form — a smaller, collapsed, and misshapen rock — that would explain why its orbit is aligned with Titan's. But it remains unclear whether Hyperion is a fragment of Titan's predecessor or a lost moon that merged with it.

According to the study, Saturn's rings may have formed hundreds of millions of years after the event. Titan's expanding orbit interacted with some of Saturn's inner moons, disturbing them to the point of causing them to collide with each other. Some of the resulting debris survived as the rings.

The best way to test the theory is to use NASA's Dragonfly — a nuclear-powered spacecraft about the size of a car that will fly over Titan's surface and land at various locations to collect and analyze samples with its onboard instruments. It is currently scheduled to launch in 2028 and arrive at Titan by the end of 2034.

"Dragonfly," seen here in an artist's concept, will be able to land on Titan's surface.

"It's complicated"

The evolution of the moons in the Saturn system and the origin of the rings are fascinating puzzles that have intrigued scientists, said Linda Spilker, a senior researcher and planetary scientist at NASA's Jet Propulsion Laboratory, who was not involved in the study.

"The rings could be only a few hundred million years young, or they could have formed at the same time as Saturn. This study provides compelling evidence for the formation of the rings of Hyperion and Saturn long after the formation of Saturn ," Spilker said in an email.

Saturn and its moons rotate and orbit with a variety of beats and resonances, according to William B. Hubbard, a professor of planetary sciences at the University of Arizona, who was also not part of the research.

“Saturn wobbles like a tornado at a frequency that is suspiciously close to a fundamental frequency of the solar system, but is not completely in sync, suggesting that some kind of relatively recent disruption may have occurred. A 2022 study proposed that there was a missing satellite, called Chrysalis, responsible for the formation of the rings, but the probability of such an event was disappointingly low,” Hubbard explained in an email.

A view of Titan from Cassini, with the sun illuminating the moon's north polar seas.

The scenario proposed by Cuk and his colleagues offers a complicated but highly plausible sequence of events that explains the Saturn system as scientists see it today, according to Carl Murray, a professor of mathematics and astronomy at Queen Mary University of London. Murray was not involved in the work, but was a member of the Cassini team.

Astronomers have long suspected that the Saturn system had evolved since its formation, but detailing the rate of change had always been a problem, he noted in an email.

One of the many legacies of Cassini's 13 years of detailed measurements, combined with historical data, has been the discovery that Titan's orbit is expanding much faster than expected, Murray said.

“The Saturn system is a dynamical paradise with numerous numerical relationships – called resonances – between the orbital periods of its moon pairs. ‘It’s complicated’ is an apt description of all these dynamical relationships over the past 400 million years, but the authors identify Titan’s role as key to our understanding of the Saturn system.” / CNN