Of the solar system’s planets, Saturn piques the human imagination with its signature rings and impressive moon count of 274. But compelling new research reignites theories of an ancient collision shaping Saturn’s environment as we know it today—especially Titan, its biggest moon.
The study, accepted for publication in the Planetary Science Journal, addresses a well-known mystery surrounding the unusually young age of Saturn’s rings as well as the oddity of Titan’s orbit. Researchers led by the SETI Institute consider the possibility that Titan was born from a two-moon collision, the impact of which subsequently led to the creation of Saturn’s younger rings. The paper is currently available as a preprint on arXiv.
Cassini’s outstanding questions
Humanity’s first close-up of Saturn, the sixth planet from the Sun, came from NASA’s Pioneer 11 spacecraft in 1979. Voyagers 1 and 2 then made their respective flybys a couple of years later.
But it was Cassini that really brought Saturn into clearer focus. The spacecraft’s 13-year mission collected valuable data about Saturn, its rings, and its moons for Earthbound scientists to pick apart.
However, some of the data Cassini sent back challenged some long-held beliefs for astronomers. For instance, several of Saturn’s many moons had odd, lopsided orbits that didn’t quite match the equations. Saturn’s rings were also a lot younger than expected.
In addition, the planet’s internal mass was more concentrated at the center than astronomers believed, suggesting knowledge gaps in the scientific consensus surrounding Saturn’s orbital behavior.
A daring what-if
In 2022, one team of astronomers proposed that these discrepancies could make more sense if Saturn had lost a moon around 100 million years ago, which is when Saturn’s younger rings presumably formed. The latest study tests this hypothesis, using computer simulations to check whether an extra moon could fly close enough to Saturn to form rings.
Of course, the effect of such a collision would have to be consistent with the distribution and characteristics of Saturn’s moons today, the team noted in the paper. Accordingly, what clued the researchers into a good starting point was a consistent anomaly in their simulations.
“Hyperion, the smallest among Saturn’s major moons, provided us the most important clue about the history of the system,” Matija Ćuk, the study’s lead author