Saturn’s outermost ring stuns astronomers
A new study, reported today in Nature, has found that Saturn’s outermost ring is nearly 300 times the size of the planet it orbits.
“Nobody expected rings to ever be this large,” says lead author, Professor Douglas Hamilton of the University of Maryland.
“The textbooks all say that rings are small, located close to their planet.”
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Will all the particles in the ring eventually fall down or will the particles be pushed away?
CrazyNeutrino said:
Will all the particles in the ring eventually fall down or will the particles be pushed away?
As the article says, the individual particles can stay in the ring for millions or billions of years, and are continually being renewed due to small impacts on Phoebe.
Bubblecar said:
CrazyNeutrino said:Will all the particles in the ring eventually fall down or will the particles be pushed away?
As the article says, the individual particles can stay in the ring for millions or billions of years, and are continually being renewed due to small impacts on Phoebe.
Thats the bit that made me wonder
CrazyNeutrino said:
Will all the particles in the ring eventually fall down or will the particles be pushed away?
There are two opinions about this. One is that the rings are very young and are destroyed very quickly. The other is that the rings are very old and disintegrate very slowly. I haven’t seen anything definitive one way or the other.
CrazyNeutrino said:
“The textbooks all say that rings are small, located close to their planet.”
Looking up a good textbook now, De Pater & Lissauer (2001). It says that even back in 1995, Saturn’s E ring was known to be quite large, extending out to 8 Saturn radii. ie. extending further out from Saturn than the orbits of the moons Mimas, Enceladus, Tethys and Dione. The inner (A to F) rings have radial extent from 1.09 to 2.32 Saturn radii. The other outer ring, the G ring, has radial location 2.75 to 2.85 Saturn radii.
mollwollfumble said:
CrazyNeutrino said:
“The textbooks all say that rings are small, located close to their planet.”
Looking up a good textbook now, De Pater & Lissauer (2001). It says that even back in 1995, Saturn’s E ring was known to be quite large, extending out to 8 Saturn radii. ie. extending further out from Saturn than the orbits of the moons Mimas, Enceladus, Tethys and Dione. The inner (A to F) rings have radial extent from 1.09 to 2.32 Saturn radii. The other outer ring, the G ring, has radial location 2.75 to 2.85 Saturn radii.
The E ring was observed by the Keck Telescope in August 1995, but its full extent wasn’t seen until a few months later in November when the Hubble Telescope took a good look. 1995 was a good year because in that year Saturn’s rings were seen edge on, making the more diffuse and distant rings easier to spot.
But that’s a long way short of 300 Saturn radii for the Phoebe ring. It’s not at all unusual for Moons to interact with rings, such as supplying particles, but this is really extreme.
> Iapetus is a moon that’s unlike anything else in the solar system, it’s black on one side and white on the other due to this Phoebe ring
That makes perfect sense. Iapetus is a lot further out than Dione, and the two-tone colour is definitely consistent with interaction with dust in a ring.
> Wise satellite
This small satellite has led to a whole heap of new discoveries. It was tuned to detect the radiation from asteroids and hotter objects. The rings of Saturn are considerably cooler than that, but would still be within the detection temperature range. Note that dithering was used by the WISE satellite to deliberately and artificially enlarge the size of small objects, so it wasn’t initially obvious that the dithering of Saturn wouldn’t swamp the picture taken of the rings.
mollwollfumble said:
CrazyNeutrino said:
Will all the particles in the ring eventually fall down or will the particles be pushed away?
There are two opinions about this. One is that the rings are very young and are destroyed very quickly. The other is that the rings are very old and disintegrate very slowly. I haven’t seen anything definitive one way or the other.
I imagine when they mean young its geological time scale young but could be hundreds or thousands of years in human terms so we think of them as old
Cymek said:
mollwollfumble said:
CrazyNeutrino said:
Will all the particles in the ring eventually fall down or will the particles be pushed away?
There are two opinions about this. One is that the rings are very young and are destroyed very quickly. The other is that the rings are very old and disintegrate very slowly. I haven’t seen anything definitive one way or the other.
I imagine when they mean young its geological time scale young but could be hundreds or thousands of years in human terms so we think of them as old
Yes. In solar system tems anything under 10 million years is young, perhaps even 100 million years.