Images of Saturn are characterised by its rings (although it is not the only planet to have rings, these rings are the most complex and magnificent). Saturn’s ring system is far more expansive than any other planet in the Solar System – 100 million times as massive as Jupiter’s.
An instantly recognisable feature with Saturn is the positioning of the rings, which tilt giving the iconic image of the giant planet (Saturn is a gas giant with an average radius of about nine and a half times that of Earth). The tilt is technically known as Saturn’s obliquity.
As to why the rings of Saturn take this position is something that has puzzled scientists for many decades. Now the answer may have been found and it could relate to a ‘missing’ moon. This may also explain why the rings are far younger than the planet itself, by billions of years.
Saturn’s rings and tilt may relate to a past event where an object smashed a moon to bits, and this destructive event led to the formation of Saturn’s rings. This is according to a research paper from the Massachusetts Institute of Technology. The research is based on observations taken by the Cassini space probe. Data from the probe led to the scientists using mathematical equations that describe a planet’s precession.
Saturn has 83 moons so it may seem odd that one more moon would have carried such significance. However, the lost moon hypothesis is now seen as the most likely reason for Saturn’s rings and tilt. In proposing a lost moon of Saturn, the researchers have named the former moon Chrysalis.
Chrysalis is thought to have been very large and to have orbited Saturn for several billion years, pulling and tugging on the planet in a way that kept its tilt in resonance with the planet Neptune. The researchers estimates that around 160 million years ago Chrysalis became unstable and came too close to its planet in what is termed a ‘grazing encounter’ that pulled the satellite apart (due to a chaotic orbital zone).
The loss of the moon was sufficient to remove Saturn from Neptune’s grasp and leave it with the present-day tilt. It is also theorised that while most of Chrysalis’ structure will have impacted with Saturn, a some of the moon’s fragments are most likely to have remained suspended in orbit.
The effect of gravitational forces will have eventually broken these fragments into small icy chunks and these went on to form the planet’s reflective signature rings.
The research appears in the journal Science, titled “Loss of a satellite could explain Saturn’s obliquity and young rings.”
