Saturn's 53 moons: Some may not be the ringed planet's first set of satellites
Saturn鈥檚 famous rings and some of its 53 moons might be of modern vintage, according to researchers at the Search for Extraterrestrial Life Institute (SETI) and the Southwest Research Institute.
Scientists say the moons could have been born as recently as a hundred million years ago. It sounds like a long time to us now, but researchers say that time period reflects just two percent of Saturn鈥檚 total life span.
What happened to cause the birth of the moons?
", but their orbits were disturbed by a special kind of orbital resonance involving Saturn's motion around the Sun,鈥� said the study鈥檚 principal investigator Matija Cuk in a press release from SETI. 鈥淓ventually, the orbits of neighboring moons crossed, and these objects collided. From this rubble, the present set of moons and rings formed."
Unlike Earth, Saturn has many moons. As their orbits grew due to tidal effects, the moons came to share what is called orbital resonances. A pair of moons that enter into an orbital resonance have linked orbits. One moon might have an orbit that lasts exactly a third, quarter, or half, etc., of its partner moon鈥檚 orbit.
When this happens, the participating moons can impact each other鈥檚 orbits, tilting and elongating them.
Researchers used computer simulations to model the evolution of the moons鈥� orbits. They examined today鈥檚 orbits and future orbits projected by computer modeling to look backward in time and determine the original positions of the moons.
Some of Saturn鈥檚 moons, including Tethys, Dione, and Rhea, have not moved far from their original orbits, meaning that they have likely not crossed paths with other moons often.
Because moons like Tethys and Dione have relatively similar orbits to the ones they would have had at their birth, researchers surmised that one of two things must be true. Either the moons鈥� tidal evolution must be extremely slow, or they must be far younger than Saturn itself.
Because Enceladus, another one of Saturn鈥檚 moons, has intense tidal heating to this day and produces ice geysers as a result, researchers were able to rule out slow tidal evolution as a cause. The estimate that the moons likley formed during the Cretaceous period, best known to us as the time dinosaurs roamed the Earth.
Researchers also believe that Saturn鈥檚 rings were created relatively recently for similar reasons. Although scientists initially believed that the rings were as old as Saturn itself, astronomers discovered in 2012 that tidal effects were causing the rings to grow rapidly outward. Given that the rings are still close to the planet (in astronomical terms), leads researchers to believe that they are also recent phenomena.
