Saturn's rings are just 100 million years old

Saturn's rings are just 100 million years old



Saturn's rings could be as young as 100 million years old and formed when dinosaurs still roamed Earth.

This contradicts the common view that they are 4.4 billion years old - the same age as Saturn.

The new age is implied from data gathered by Cassini as it makes its final orbits before the death dive.

A comet or moon probably came too close to Saturn and then broke apart around the planet forming the distinct halo, researchers suggest.

This means it would have looked completely different when dinosaurs first set foot on the planet around 230 million years ago.   



If this initial data is found to be correct, researchers say we could be looking at Saturn in a very unique period in planet's history.

On 15 September Cassini will make its mission-ending plunge into Saturn's atmosphere.

It will soon run out of fuel and Nasa wants to crash it in order to stop it potentially contaminating other life-forms that could exist on other moons.

The craft has been plunging between the top of Saturn's atmosphere and the rings - a previously unexplored area which has returned some unique data.

These plunges have allowed it to get information about the weight of Saturn's rings and therefore an idea of how old they are.

Using Cassini, scientists have collected a detailed map of the gravitational field of the planet, writes BBC.

They have been able to essentially weigh the weight of the rings which in turn tells us something about their age - the bigger they are the older they are likely to be.

For example if they formed at the same time as Saturn 4.6 billion years ago they would have needed extremely large masses to counteract the forces against them.

It appears that their mass is actually a lot less than was previously thought.

This means they could have been produced by an object such as a moon or comet breaking up around Saturn as little as 100 million years ago.



'For younger rings, it would require a comet, or a centaur (one of a group of small, icy objects), or perhaps even a moon moving too close to Saturn', Linda Spilker, Nasa's Cassini project scientist told BBC.

'But if the rings are less massive they won't have had the mass to survive the micro-meteoroid bombardment that we estimate to have happened since the formation of the planet', said Dr Spilker.



'So, we're heading in the direction of the rings being perhaps 100 million years old or so, which is quite young compared to the age of the Solar System,' she said.

The rings are predominantly composed of water ice particles, up to several feet in size, but these particles are continually 'polluted' by bombarding micrometeoroids.

But despite studying them intensely, researchers are still unsure exactly when the iconic rings formed.



Another study in 2016 also suggested the rings could as young as 100 million years old.

Researchers at Cornell University studied an almost forgotten set of data, collected ten years ago by Nasa's Cassini mission.

'Water ice comprises the bulk of Saturn's rings, yet it is the small fraction of non-icy material that is arguably more valuable in revealing clues about the system's origin and age,' the researchers wrote in a new study, published in the journal Icarus.

In the study, Cornell's Zhimeng Zhang and co-authors studied a set of data collected early in Cassini's mission.

The instruments used measured the entire ring composition, rather just the surfaces' icy layers.

Saturn's C ring is the most 'polluted' due to its relative low mass, making it easier to acquire a higher proportion of non-icy material.



'This makes the C ring ideal for investigating ring contamination and piecing together age and history,' Zhang told SciNews.

After sifting through reams of data, the authors showed most regions in the C ring contained between 1 and 2 per cent rocky silicates.

Combining this with estimates of the micrometeoroid flux places the C ring somewhere between 15 and 100 million years old.

'None of the current origin scenarios predict the rings are likely younger than 3.8 billion years old,' said Dr Zhang.

'This will force a rethinking of ring origin models.'