Saturn's rings are disappearing
Saturn is one of the most striking sights in our Solar System, not least because of its prominent rings. But new research suggests the rings might be disappearing at a surprising rate.
A view of Saturn’s rings captured by the Cassini spacecraft on 21 July 2016. Just below rings can be spotted Saturn’s tiny moon Mimas. Image Credit: NASA/JPL-Caltech/Space Science Institute.
Saturn’s iconic rings have less than 100 million years to live, according to new research carried out by UK scientists.
The rings, which are made mostly of ice, are being pulled into Saturn by the planet’s gravity.
It is estimated that the process drains the equivalent of an Olympic swimming pool from Saturn’s rings in 30 minutes.
The research was carried out by Dr Tom Stallard, Associate Professor in Planetary Astronomy at the University of Leicester and Dr James O'Donoghue, formerly of the University of Leicester and now at NASA’s Goddard Space Flight Center.
The results reveal that Saturn’s rings are disappearing at the maximum rate estimated from Voyager 1 and 2 observations made decades ago.
“We estimate…the entire ring system will be gone in 300 million years,” says Dr O’Donoghue.
“Add to this the Cassini-spacecraft detected ring-material falling into Saturn’s equator, and the rings have less than 100 million years to live.”
A NASA video showing the science behind the disappearance of Saturn's rings. Image Credit: NASA's Goddard Space Flight Center
When compared to Saturn’s age of over 4 billion years, the potential lifespan of the young rings is relatively short.
“The young age of the rings has some really startling implications.
It is possible, in the age of the dinosaurs, that Saturn’s rings were even larger and brighter than we see them today,” says Dr Stallard.
“Something dramatic must have happened around Saturn to make them this large, long after the planet itself formed.”
When the Voyager spacecraft studied Saturn in the 1980s, data revealed changes in Saturn’s ionosphere and density variations in the rings.
It also revealed three dark bands in images of Saturn’s upper atmosphere.
These bands were eventually linked to the shape of the ringed planet’s magnetic field, suggesting electrically-charged ice particles from the rings were travelling along magnetic field lines and depositing water in Saturn’s upper atmosphere.
The water seemed to be washing away the haze from Saturn’s stratosphere, creating the appearance of narrow dark bands in the Voyager images.
Dr O’Donoghue’s research will next look at how Saturn’s rings change in accordance with the planet’s seasons.
Iain Todd is BBC Sky at Night Magazine's Content Editor. He fell in love with the night sky when he caught his first glimpse of Orion, aged 10.