New models suggest that Saturn’s gravity tore apart a moon, Chrysalis, about 160 million years ago.
The ancient moon could explain two long-standing mysteries: Saturn’s iconic rings and its dramatic tilt.
Researchers think Chrysalis was about the size of Iapetus, Saturn’s third largest moon.
Scientists say a single moon can clear up two cosmic mysteries about Saturn.
When Galileo Galilei first peered at Saturn in 1610, the astronomer noted that the planet had “ears.” It turned out to be the iconic rings of Saturn. How and when these rings formed have been puzzling astronomers ever since.
Another Saturn mystery is its dramatic 27-degree tilt to one side. According to researchers, that slope is too great to have formed when the gas giant did or to have been the result of collisions that toppled the planet. By comparison, the Earth’s tilt fluctuates between 22.1 and 24.5 degrees.
In a study published Thursday in the journal Science, researchers ran a series of simulations that suggest Saturn’s rings and its unusual inclination could have formed 160 million years ago, when one of its icy moons destabilized and entered a chaotic orbit. fell around the planet. Eventually, the moon — which researchers called Chrysalis — got too close to the gas giant and was ripped apart.
The models are based on data from the final stage of NASA’s Cassini mission, which orbited Saturn and its moons for 13 years before plunging into the planet’s atmosphere in 2017.
Today, the giant’s planetary system is home to 83 moons. Researchers think Chrysalis was about the size of Iapetus, Saturn’s third largest moon.
Researchers said about 99% of Chrysalis’s remains ended up in Saturn’s atmosphere, while the remaining 1% remained in orbit, leaving behind a debris-strewn ring that formed the planet’s iconic large rings.
“Like a butterfly’s pupa, this satellite was inactive for a long time and suddenly became active, and the rings emerged,” said Jack Wisdom, lead author and professor of planetary sciences at MIT, in a statement.
Planetary scientists have long suspected that Saturn’s tilt may come from gravitational interactions with Neptune. To gather information about the planet’s tilt, researchers used simulations to calculate Saturn’s moment of inertia, which relates to how much force it took to tilt the planet on its side. They found that although Saturn was once gravitationally synchronized with Neptune, something changed about 160 million years ago, removing Saturn from Neptune’s influence.
“Then we started looking for ways to get Saturn out of Neptune’s resonance,” Wisdom said. Resonance occurs when two celestial bodies keep realigning after a certain number of orbits. They theorized that an ancient moon, Chrysalis, could have kept Saturn under Neptune’s influence until it disintegrated, allowing Saturn to move just out of resonance with Neptune.
Wisdom stressed that more data is needed to see if the theory holds up. “It’s a pretty good story, but like any other result, it’s going to have to be explored by others,” Wisdom said. He added that the small moon appears to have functioned like a pupa butterfly, with the rings emerging as it was ripped apart by Saturn’s gravity.
Read the original article on Business Insider