Research based on data from the final phase of NASA’s Cassini mission suggests that Saturn may have been ringless for most of its 4.5 billion-year existence. But about 160 million years ago, an inner moon got so close to the gas giant that it broke apart and found its own orbit along a path of broken ice.

The hypothetical lost satellite was nicknamed Chrysalis

“Like a butterfly chrysalis, this satellite was dormant for a long time, then suddenly became active, and the rings appeared.“said Jack Wisdom, professor of planetary science at the Massachusetts Institute of Technology and lead author of the study.

The Wisdom team first set out to explain why Saturn is tilted 27 degrees on its axis. Theoretical models suggest that this tilt is due to Saturn being in gravitational resonance with Neptune. But these types of models are often sensitive to small changes in a wide variety of variables.

As the Cassini mission, which orbited Saturn from 2004 to 2017, filled in details from Saturn’s internal structure to the dynamics of the planet’s 83 moons, the initial explanation fell apart. These new details suggest that Saturn, at some point in the past, moved out of Neptune’s sphere of influence.

This has prompted scientists to investigate catastrophic events that may have caused this. The missing moon scenario provided an unexpectedly sharp match to the data. “We tried to explain Saturn’s tilt. a declarat wisdom. “But we find that we need to propose an additional satellite and then exclude the satellite again.

Gnana and colleagues conducted simulations to determine the properties of a hypothetical moon. They suggested that between 100 million and 200 million years ago, Chrysalis entered a chaotic orbital region and experienced a close encounter with Saturn’s moons Iapetus and Titan. It eventually came close to Saturn, and this dramatic encounter tore the moon apart, leaving behind a ring full of debris.

The loss of the chrysalis would explain the current tilt of Saturn and its rings. This would be consistent with measurements of the rings’ chemical properties, which date them to about 100 million years old, but some have dismissed it as unclear how the rings could have materialized so late in the planet’s history. “I think we make a very compelling case.”a declared Wisdom.

“We’ll never be sure if there was an extra moon in Saturn’s system, but the explanation [mai multor] Puzzles with a theory are a good return on investmentAnd,” Tremaine said.

Saturn’s rings weigh about 15 million trillion kilograms and are made almost entirely of ice, 95% of which is fresh water, and the rest is made up of rocks and metals.