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\n Titan, Saturn\u2019s largest moon, with the giant planet behind it in a view from the Cassini-Huygens spacecraft<\/p>\n ZUMA Press, Inc.\/Alamy<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n The story of Saturn, its rings and moons, may have started with its largest moon, Titan. A collision between an early proto-Titan and a smaller object about 400 million years ago could have set into motion the series of events that formed Saturn\u2019s iconic rings and altered both the planet\u2019s wobble and the orbits of its moons.<\/p>\n The Saturn system is awash in mysteries. Its rings seem to be younger than expected, the planet\u2019s wobble isn\u2019t tied to the motion of Neptune as simulations have suggested it ought to be, and its small moon Iapetus has a strangely tilted orbit. Titan itself has strangely few craters and an oval, or eccentric, orbit.<\/p>\n <\/p>\n A huge collision that created the Titan we see today could explain all of these elements. \u201cThis is sort of a grand unified theory that covers all of the major problems,\u201d says Matija \u0106uk at the SETI Institute in California, who led the research team behind this work. \u201cWe had some idea about each of them, but this might be how they relate in one story that can be tested.\u201d<\/p>\n It starts with a hypothesised extra moon called Chrysalis in the outer reaches of the system, which was proposed in 2022 to explain how Saturn\u2019s wobble got decoupled from Neptune. The idea was that Chrysalis got tossed towards Saturn and broke up to form the rings, destabilising Saturn\u2019s wobble and Iapetus\u2019s orbit in the process. However, \u0106uk and his colleagues noticed that in simulations, the most likely outcome was that Chrysalis would collide with Titan.<\/p>\n That\u2019s a problem, says \u0106uk. \u201cIf there was a collision with Titan, it could not have become the rings.\u201d So he and his team went about calculating what would happen if Chrysalis did smash into Titan. They found that such a collision about 400 million years ago would erase Titan\u2019s craters and push its then-circular orbit to become elliptical, as well as creating a shower of debris. The smaller moon Hyperion could be a piece of that debris, which would explain why it is so much younger than Saturn\u2019s other moons.<\/p>\n Then, over time, Titan\u2019s changing orbit would have destabilised the small inner moons and sent them careening into one another, grinding each other down into the tiny particles that now make up Saturn\u2019s rings. \u201cIt all starts from Titan and then trickles down to a second catastrophe in the inner system,\u201d says \u0106uk.<\/p>\n \u201cIf a collision with Titan 1.0 can explain many other things about the Saturn system, then I think that would really centre Titan as being pivotal to how we see the system today,\u201d says Sarah H\u00f6rst at Johns Hopkins University in Maryland. \u201cI appreciate the elegance of how many Saturn system problems it would solve at once.\u201d<\/p>\n Evidence that could prove or rule out this scenario isn\u2019t too far off. NASA\u2019s Dragonfly mission, which is slated to launch in 2028 and arrive at Titan in 2034, will get a close look at Titan\u2019s surface, which should help determine whether it did merge with Chrysalis. If so, we may finally understand some of the many oddities of Saturn.<\/p>\n Topics:<\/p>\n<\/section><\/div>\n