Saturn’s largest moon, Titan, may be made of two different moons that smashed together hundreds of millions of years ago, a new study suggests. If confirmed, this epic collision could also help to solve several long-standing mysteries surrounding the gas giant, including how its iconic rings formed.

Titan is the solar system’s second-largest moon, behind Jupiter’s Ganymede. It is around 3,200 miles (5,150 kilometers) across, which is roughly 1.5 times wider than Earth’s moon and around 5% wider than Mercury.

Aside from its immense size, Titan is notable for its dense atmosphere, which consists mainly of nitrogen and is around 1.5 times thicker than Earth’s atmosphere. It is also the only solar system body, other than Earth, that has confirmed liquid on its surface, in the form of methane — making it a potential candidate for hosting extraterrestrial life. The European Space Agency’s Huygens probe touched down on Titan in 2005, making it the only moon, other than our own, that a spacecraft has landed on. Until now, researchers thought that, like most other moons, Titan formed billions of years ago via the gradual accumulation of tiny chunks of rock and dust. But in the new study, uploaded Feb. 9 to the preprint server arXiv and accepted for future publication in The Planetary Science Journal, researchers from the SETI Institute showed that this may not be the case.

Based on data collected by NASA’s Cassini probe, which flew past Titan and deployed Huygens to its surface, the SETI team proposes that Titan may have formed around 400 million years ago when two similarly massive moons slammed into each other. This collision also may have birthed another Saturnian moon, Hyperion, the researchers argue. This smaller satellite, which is around 84 miles (135 km) wide, likely formed from the debris from the collision, much like Earth’s moon did when the protoplanet Theia smashed into Earth around 4.5 billion years ago.

Additionally, the new hypothesis may explain the unusual orbits of several other Saturnian satellites, the team said. Saturn has at least 274 moons — the most of any planet — after the recent discovery of 128 natural satellites.