Saturn is one of the most distinctive planets in the solar system thanks to its iconic rings, but surprising new research suggests that those rings weren't always there. In fact, they may have formed more recently than the evolution of the dinosaurs here on Earth, reports Phys.org.
In other words, Saturn's rings — and many of its moons too — might not just be babies on a galactic timescale. They might be babies on a geological timescale. If a time-traveling scientist went back to the Age of Dinosaurs and peered through a telescope at Saturn, it might have been a far different looking system.
"Moons are always changing their orbits. That's inevitable," said Matija Cuk, principal investigator at the SETI Institute. "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."
It's a profound thing to fathom. Up until now, the working assumption about Saturn's rings was that they were primordial, as old as the planet itself. It's humbling to think that such a prominent feature of one of the largest planets in our solar system could be a recent development. The fact that we're able to witness them today is an incredibly lucky moment in the history of the solar system.
Researchers calculated the age of Saturn's rings by studying the orbital tilt of the planet's inner moons. Orbital tilt is what happens to an orbiting body when it gets tugged and yanked by the gravity from other nearby objects, essentially making it more elongated. As an object like a moon becomes elongated, it begins to tilt out of its original orbital plane. By comparing the current orbital tilt of Saturn's inner moons to predictions made through computer simulations about their implied age, scientists calculated that they are probably only around 100 million years old.
To put that in perspective here on Earth, it was a time when pterosaurs were flying through our skies and stegosaurs were munching on ferns.
"So the question arises, what caused the recent birth of the inner moons?" asked Cuk. "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."
Such an event would probably have been spectacular to witness in timelapse, if only we were born about 100 million years earlier to witness it.