Thursday, 17 January, 2019

Saturn's rings could disappear within 100 million years due to gravity

Saturn's rings could vanish much sooner than expected Saturn with no rings? It could happen, and sooner than astronomers expected
Theresa Hayes | 20 December, 2018, 04:03

Their origins remain controversial, but now they are disappearing.

Scientists aren't completely certain if Saturn was born with its lovely halo, or if it acquired its ring system later in life. These interactions force the material in the rings to get caught in the magnetic field of Saturn and pulled towards the planet by gravity.

The rate that water ice is falling onto Saturn means that eventually the rings will run out of material and disappear altogether. The probe observed ring particles moving quickly into Saturn's equator.

"What we're seeing is something on the order of about a ton and a half per second", said James O'Donoghue of NASA's Goddard Space Flight Center, in Greenbelt, Maryland, who reported the conclusions Monday in the journal Icarus.

This revelation, along with information from Cassini spacecraft research, led scientists to estimate that the rings will cease to exist in fewer than 100 million years - a short time relative to Saturn's 4-billion-year existence, O'Donoghue says. The team looked at previous research about the planet's "ring rain" that tracked how much mass was being lost. The rings are in a delicate balancing act, stuck between Saturn's gravitational pull and the orbital tugs drawing them outward into space.

Scientists first documented ring rain back in 2013, but new research, led by James O'Donoghue from NASA's Goddard Space Flight Center in Greenbelt, Maryland, shows the effect is happening much quicker than expected, and by outcome, so is the rate at which Saturn's rings are decaying.

Before Cassini took a fiery, fatal plunge into Saturn in September 2017, it completed a daring series of loops between the planet and its rings.

Scientists estimate the rings could be gone in 300 million years, but they could vanish even faster.

Saturn's iconic rings are made up of mostly frozen water which is actually getting pushed onto the planet's surface.

"We are lucky to be around to see Saturn's ring system, which appears to be in the middle of its lifetime".

"I don't think it's unreasonable, with all these numbers being so high, that we have to seriously consider that the rings won't be around forever", he said.

Neptune is also thought to have very young rings, but there's a big question mark standing over Jupiter. "We identified Enceladus and the E-ring as a copious source of water as well, based on another narrow dark band in that old Voyager image".

Researchers now hope to see how the ring rain changes during different seasons-ultraviolet light from the sun might change the quantity of the mass being lost. As the planet progresses in its 29.4-year orbit, the rings are exposed to the Sun to varying degrees. The W.M. Keck Observatory is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and the data in the form of its files are available from the Keck archive.