According to new research, an ancient moon that ruptured after orbiting close to Saturn may be the cause of the planet’s rings tilting.
Saturn’s tilt has always been evident through its rings that orbit the planet at an angle of 26.7 degrees compared to the planet’s orbit around the sun.
While it has long been thought that this is related to the gravitational force of Saturn’s neighbor, Neptune, given how closely Saturn’s rotation is related to Neptune’s orbit pattern, astronomers now believe that the connection between the two planets has since been broken.
But if Saturn is not inclined towards Neptune, what is the reason for its current tilt? And could it be related to the relatively recent formation of Saturn’s rings, which were previously estimated to be only 100 million years old?
Astronomers think they’ve found an explanation that could answer a number of these unexplained anomalies at Saturn: an extra moon that died until the rings formed.
In a new study published Thursday in the journal Science, the authors named this moon “Chrysalis.”
The study suggests that if Chrysalis existed as the moon number 84, it would have helped keep Saturn in alignment with Neptune for several billion years.
Then, about 160 million years ago, according to the researchers’ computer modeling, Chrysalis’ orbit became unstable and hit the planet itself—a catastrophic event that would have torn the Moon apart, and would also explain how Saturn was pulled out of its pattern with Neptune gaining its current tilt.
The torn cocoon pieces that did not fall on Saturn were then thrown into orbit around it, eventually collapsing into smaller ice pieces to form the planet’s rings.
Jack Wisdom, professor of planetary sciences at MIT and lead author of the new study said: He said in a press release.
The researchers say this theory corrects a number of loopholes in previous explanations of Saturn’s orbit, rings and inclination.
It was first suggested in the 2000s that Neptune and Saturn are bound by a gravitational relationship, but when NASA’s Cassini traveled to visit the planet from 2004 to 2017, its observations brought new complexities.
Cassini’s observations of Titan, Saturn’s largest moon, led to the theory that this large moon was in fact responsible for Saturn’s tilt, forcing it to align with Neptune. However, this only makes sense if the mass of the gas giant is distributed in a certain way – since the composition of the planet makes it difficult for us to know whether its mass is more concentrated towards the core or not, it is difficult to determine the moment of inertia of the planet. .
Wisdom and his colleagues set out to see if Cassini’s final observations — compiled in the last moments of its existence as the spacecraft descended toward Saturn’s surface — could shed light on this problem.
These final observations made it possible to create a gravitational field for Saturn that allowed researchers to model the way mass is distributed across the planet.
They found that the moment of inertia they were looking for meant that Saturn was actually out of alignment with Neptune. The planets are no longer in sync.
Wisdom said, “Then we went to look for ways to get Saturn out of the echo of Neptune.”
After modeling several scenarios, the team discovered that the math is balanced if a new moon is added and then subtracted in a catastrophic event.
They hypothesized that Chrysalis’ orbit became chaotic between 100-200 million years ago, and that after it had some near misses with some other large moons like Titan, Saturn nursed itself, and traveled close to the front.
Chyrsalis had to be the size of Iapetus, Saturn’s third largest moon, to explain how its destruction and loss could pull Saturn out of its resonance with Neptune.
“It’s a very good story, but like any other outcome, it needs to be scrutinized by others,” Wisdom says. “But it seems that this lost satellite was just a cocoon, waiting to be unsettled.”