Saturn is known for its magnificent network of rings, but a group of astronomers now believes that system did not exist until sometime after the age of dinosaurs began here on Earth. The vast family of satellites surrounding the gas giant may also be relatively young, according to a new study.
The moons of Saturn may have formed just around 100 million years ago, more than 130 million years after the rise of dinosaurs on our own world.
Since the 17th century, astronomers have tried their best to determine the ages of the satellites of Saturn. The most popular idea among astronomers was that the moons formed at the same time as the rest of the solar system, roughly 4.5 billion years ago.
In 2012, French astronomers showed that the moons of Saturn are drifting outward as they orbit around the giant planet. This motion is driven by tidal forces between the world and its attendant satellites creating heat within the gas giant.
"Moons are always changing their orbits. That's inevitable. But that fact allows us to use computer simulations to tease out the history of Saturn's inner moons. Doing so, we find that they were most likely born during the most recent two percent of the planet's history," said Matija Cuk of the SETI Institute.
Dozens of satellites are known to orbit around the giant world, and each appears to be spiraling away from Saturn at different rates. As they travel away from the second-largest planet in our solar system, they often influence the path of one another through the force of gravity. This effect is especially pronounced when the orbital period of one satellite is a simple fraction (say one-half or one-third) that of a neighboring moon. This effect is known as an orbital resonance.
The orbital tilts of three of the largest moons of Saturn — Rhea, Tethys and Dione, show little alteration from predicted paths. This shows these satellites have crossed orbital resonances few times, suggesting the bodies may have formed close to where we see them today.
The action of ice volcanoes on the moon Enceladus suggests tidal forces acting on the satellite for roughly 100 million years, providing an age for the moon. Investigators on this study suggest that an ancient set of satellites may have collided long ago, forming the inner moons and the massive network of rings we see in the modern age.
Analysis of the rings and satellites of Saturn was detailed in The Astrophysical Journal.