Saturn’s gravitational pull shredded an ancient moon, creating its iconic rings and unusual tilts, new research suggests

Saturn’s gravitational pull shredded an ancient moon, creating its iconic rings and unusual tilts, new research suggests

Scientists suggest Saturn's lost moon, which they call Chrysalis, tugged at the planet until it tore apart, forming rings and contributing to Saturn's tilt.

Scientists suggest that Saturn’s ancient moon, which they call Chrysalis, pulled on the planet until it split apart, forming rings and contributing to Saturn’s tilt.NASA/JPL-Caltech/Space Science Institute/G. Ugarkovic

  • New models suggest that Saturn’s gravity destroyed the moon, Chrysalis, about 160 million years ago.

  • The ancient moon could explain two long-standing mysteries: Saturn’s iconic rings and dramatic tilt.

  • Researchers think Chrysalis was probably about the size of Iapetus, Saturn’s third largest moon.

Scientists say one moon could clear up two cosmic mysteries about Saturn.

When Galileo Galilei saw Saturn for the first time in 1610, the astronomer noticed that the planet looked like “ears.” They turned out to be the iconic rings of Saturn. How and when these rings formed has puzzled astronomers ever since.

Another mystery of Saturn is its dramatic inclination of 27 degrees to one side. According to researchers, that tilt is too big to have been made when the giant gas or as a result of collisions that hit the planet. In comparison, the Earth’s tilt oscillates 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 unusual tilt may have formed 160 million years ago, when one of its icy moons destabilized and fell into a chaotic orbit 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 phase of NASA’s Cassini mission, which spent 13 years orbiting Saturn and its moons before re-entering the planet’s atmosphere in 2017.

On July 29, 2011, Cassini captured five of Saturn's moons in one frame.

Cassini captured five of Saturn’s moons in one frame, on 29 July 2011.NASA/JPL-Caltech/Space Science Institute

Today, there are 83 moons in the giant’s planetary system. Researchers think Chrysalis was probably about the size of Iapetus, Saturn’s third largest moon.

Researchers said that about 99% of the remains of Chrysalis fell into Saturn’s atmosphere, while the remaining 1% remained in orbit, leaving behind a ring of debris that became the planet’s iconic great rings.

“Just like the chrysalis of a butterfly, this satellite had been dormant 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.

Saturn's rings show their subtle colors in this view captured on August 22, 2009, by NASA's Cassini spacecraft.

Saturn’s rings show their subtle colors in this view captured by NASA’s Cassini spacecraft, on August 22, 2009.NASA/JPL-Caltech/Space Science Institute

Planetary scientists have long suspected that Saturn’s tilt may have come from gravitational interactions with Neptune. To gather information about the planet’s tilt, the researchers used simulations to calculate Saturn’s moment of inertia, which refers to the amount of force needed to push the planet on its side. They found that while Saturn may once have been in gravitational sync with Neptune, something changed about 160 million years ago, removing Saturn from Neptune’s influence.

“Then we looked for ways to get Saturn out of the Neptune resonance,” Wisdom said. Resonance occurs when two celestial bodies keep realigning after a certain number of orbits. They theorized that an ancient moon, Chrysalis, may have kept Saturn under Neptune’s influence until it split, allowing Saturn to move directly out of resonance with Neptune.

Wisdom stressed that more data will be needed to see if the theory holds up. “It’s pretty good news, but like any other result, it’s going to have to be examined by other people,” Wisdom said. He added that the small moon appears to have acted like a butterfly in the chrysalis stage, with its rings emerging as it was torn apart by Saturn’s gravity.

Read the original article on Business Insider

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