Saturn’s rings and inner moons are younger than the dinosaurs, about 100 million years old, according to a new study. That’s a surprise for many astronomers who had assumed the Saturn system we know today formed along with the planet, roughly 4 billion years ago. This new information is not good news for researchers still looking for signs of life in our own cosmic backyard.
Saturn has 62 known moons in orbit, plus its rings. Scientists believe that the outer bodies, like Titan and Iapetus, are about 4 billion years old. But those bodies closer to Saturn, like Tethys, Dione, Rhea, and the iconic rings, are only 100 million years old, meaning that they came about during the time when dinosaurs and, according to the Washington Post, even bees roamed the Earth.
How did astronomers figure out the young age of Saturn’s rings and inner moons?
According to the scientists, tidal interactions between the moons and the fluids deep within the interior of Saturn gradually push the planets farther out, making their orbits grow. The tidal forces from Saturn are reportedly quite strong — enough to power ice geysers on the nearby moon Enceladus.
Likewise, the moons occasionally enter what is called an orbital resonance, forcing the bodies’ orbits to become irregular.
A SETI press release explained that an orbital resonance is “when one moon’s orbital period is a simple fraction (for example, one-half or two-thirds) of another moon’s period. In these special configurations, even small moons with weak gravity can strongly affect each other’s orbits, making them more elongated and tilting them out of their original orbital plane.”
Because of these different interactions, the rings and inner planets should have been forced farther from the planet, if they really were 4 billion years old. According to the team’s simulations, the current orbits suggest that they are more like 100 million years old.
If the dinosaurs had telescopes they could have seen something spectacular, and perhaps spotted the asteroid that would eventually destroy them.
But all this leads to an even more interesting question — how were the inner planets and the rings formed?
Matija Cuk, principal investigator at the SETI Institute, admits they don’t have an answer yet, only a hypothesis.
“Our best guess is that Saturn had a similar collection of moons before, but their orbits were disturbed by a special kind of orbital resonance involving Saturn’s motion around the Sun. Eventually, the orbits of neighboring moons crossed, and these objects collided. From this rubble, the present set of moons and rings formed.”
This discovery is bad news for people searching for extraterrestrial life in the solar system. Enceladus is believed to have a salty liquid water ocean under its surface and be geologically active, and within its geysers, researchers have discovered basic hydrocarbons. All of the evidence has led some researchers to believe the moon might be one of solar system’s best bets for finding life.
But if Enceladus is just 100 million years old, then that possibility is highly unlikely. The earliest life on Earth took hundreds of millions of years to form, and those are the most optimistically short time estimations.
Saturn’s rings have come to represent the sixth rock from the sun; now that we know they’re younger than the dinosaurs, they might also come to represent how ever-changing our cosmic surroundings really are.
[Photo by NASA/JPL-Caltech/SSI via Getty Images]