Study reveals Saturn’s rings and tilt could be product of an ancient ‘missing moon’

Image credit: Current Science Daily

Saturn’s missing moon, Chrysalis, is thought to have been pushed onto the planet until it tore apart, generating rings and adding to Saturn’s tilt.

Saturn may have once been in sync with Neptune, but according to recent modelling research by scientists at MIT and other institutions, Saturn has since eluded Neptune’s influence. What caused this realignment of the planets? The one carefully examined theory the team has is that of a missing moon.

The team claims in a paper published in Science that Saturn, which currently has 83 moons, originally had at least one additional satellite that they have named Chrysalis. According to their theory, Chrysalis and its siblings orbited Saturn for billions of years while applying pressure to keep the planet’s tilt, or “obliquity,” in resonance with Neptune.

Torn apart by a grazing encounter, Chrysalis is supposed to have gotten unstable some 160 million years ago and approached its planet too closely. Enough of the moon was lost for Saturn to be released from Neptune’s influence and acquire its current tilt.

Furthermore, the team hypothesises that while the majority of Chrysalis’ body fragments may have collided with Saturn, some of them may have remained suspended in space and later disintegrated into tiny frozen pieces to form the planet’s distinctive rings.

Therefore, the missing satellite could shed light on two open questions: Saturn’s current tilt and the age of its rings, which were formerly thought to be just approximately 100 million years old, much younger than the planet.

The main author of the new study and professor of planetary sciences at MIT Jack Wisdom explains that this satellite was long dormant until suddenly becoming active and the rings developed.

The study’s other co-authors are Rola Dbouk from MIT, Burkhard Militzer from Berkeley University, William Hubbard from the University of Arizona, Francis Nimmo and Brynna Downey from Santa Cruz University, and Richard French from Wellesley College.