Sep 21, 2019

Saturn's rings may be more ancient than previously thought

Saturn as seen by the Hubble Space Telescope. Photo: NASA/ESA

Saturn's rings may be more ancient than previously thought, according to a new analysis published in the journal Nature Astronomy this week.

Why it matters: The true age of the rings has major implications for the age of Saturn's moons. Many scientists think that Saturn's moon Enceladus is one of the places in our solar system most likely to host life, but if the moon is young, life may not have had enough time to develop.

What they found: Earlier studies have suggested that the rings are young, at about 10 million–100 million years old, based on estimates of their mass and appearance.

  • The rings themselves — which are thought to have been formed from water-ice — don't show evidence of a ton of pollution from meteoroids and dust falling onto the rings, suggesting a young age based on the rate of pollution expected from Cassini data.
  • However, the new study shows that it's possible that the rings just appear to be young: The bombardment rate of the rings by pollution may just be higher today than it was in the past, or the rings are able to somehow clean themselves over time, making them look younger than they are.
  • The analysis also suggests that the total mass of the rings today is more in line with models that produce an ancient system of rings around Saturn.

What's next: The mystery surrounding the age of Saturn's rings may never be solved definitively, but learning more about their eventual fate may be easier than piecing together its past, astronomer James O'Donoghue, who is unaffiliated with the new study, told Axios via email.

  • O'Donoghue and his team have calculated that, based on the rate that the ring particles are "raining" into Saturn's atmosphere, the planet's most distinctive feature only has about 300 million years left before they fade away.

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An interstellar comet revealed

Comet 2I/Borisov. Photo: Gemini Observatory/NSF/AURA

The interstellar comet discovered in August looks very similar to comets originating in our own solar system, according to a new study in Nature Astronomy this week.

The big picture: Comet 2I/Borisov represents just the second-known interstellar object to make its way through our solar system, and it's astronomers' best chance so far to study a piece of a distant star system at close range.

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