A long-lost moon explains the origin of Saturn’s rings

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With its striking rings and tilted axis, Saturn is the brightest planet in the solar system. Now scientists say they have a new theory for how the gas giant got her signature look.

The planet’s rings may have come from an ancient missing moon, according to space scientists from the Massachusetts Institute of Technology and the University of California, Berkeley.

Today Saturn has 82 moons, according to NASA. The research team proposed that the ringed planet may have had another orbiting the planet for a few billion years.

But about 160 million years ago, this moon became unstable and got too close to Saturn in what researchers described as a “grazing encounter” that shattered the moon.

While the gas giant likely swallowed 99% of the moon, the rest hung in orbit, breaking into small chunks of ice that eventually formed the planet’s rings, the scientists suggested.

Previous search had estimated Saturn’s rings to be 100 million years old – much younger than the planet itself although their age is a hotly debated topic. This latest study provides a potential explanation for their later origin.

“Various explanations have been offered, but none are entirely convincing. The cool thing is that the previously unexplained young age of the rings is naturally explained in our scenario,” study author Jack Wisdom, a professor of planetary sciences at the Massachusetts Institute of Technology, said in a statement. hurry.

The new research, published in the journal Science on Thursdayis based on computer modeling from measurements made in 2017 at the very end of NASA’s Cassini mission, which spent 13 years exploring Saturn and its moons.

The study also sheds light on two other puzzling features of Saturn.

Previously, astronomers suspected the planet’s 26.7-degree tilt stemmed from gravitational interactions with its neighbor Neptune, but according to the study, the lost moon theory may provide a better explanation. The two planets may have once been in sync, and the loss of a moon could have been enough to dislodge Saturn from Neptune’s pull and leave it at its current tilt.

“The tilt is too large to be the result of known formation processes in a protoplanetary disk or subsequent large collisions,” Wisdom said.

Scientists believe the same event may have caused Saturn’s moon Titan – which is the second-largest moon in the solar system and larger than the planet Mercury – to embark on its curious orbit. The moon is rapidly migrating out of Saturn at about 11 centimeters (4.3 inches) per year, according to the study.

The researchers named the lost moon Chrysalis, because of how they think it transformed the planet.

“Just like a butterfly’s chrysalis, this satellite slept for a long time and suddenly became active, and the rings emerged,” Wisdom said.

He added that the research told “a pretty good story”, but would need to be tested and reviewed by other astronomers.

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