How Did Saturn Get its Rings?

The exact origins of Saturn’s rings have long troubled astronomers, with two main competing theories in competition with each other. Either the rings are remnants of a collapsed moon, or they are simply leftover material from the planet’s formation.

Planetary scientists have recently designed a model that would seem to support the former hypothesis and also explain Saturn’s unusually pronounced tilt. Saturn’s 27° tilt is believed to be caused by its orbital resonance with Neptune, wherein the two planets exert gravitational influence on each other, as well as Titan’s slow migration away from Saturn. But this newly designed model shows Saturn is no longer in total sync with Neptune, suggesting a massive impact in its past knocked it out of rhythm.

The project, headed up by planetary dynamicist Jack Wisdom and his team at MIT, ran simulations that support the model of a moon impacting Saturn in the last 100 million years and shredding itself, providing the material for Saturn’s rings to form.

This wouldn't be the first theory of a planetary impact becoming a celestial feature. Earth's own moon is hypothesized to have come from a massive impact with a body called Theia. The debris eventually formed our unusually large moon. Like the suggested Saturn impact, this also gave Earth it's axial tilt.

The findings are tentative: of the 390 simulations run, many had the hypothetical moon collapse with another of Saturn’s satellites, or simply eject itself into space. But 17 of the simulations showed an impact with Saturn itself, which would account for both the planet’s tilt and its iconic rings. It’s far from proof, but this project has rekindled debate around a perennial mystery of our solar system.

Something else intriguing about Saturn's rings is just how new they are. They're only 100 million years old, which may sound long but is really only a blink of the eye in astronomic time. To give some perspective, if dinosaurs had telescopes, they may have been able to witness the formation themselves!