APOD: Density Waves in Saturn's Rings from... (2017 Aug 08)

[APOD Robot]

Density Waves in Saturn's Rings from Cassini

Explanation: What causes the patterns in Saturn's rings? The Cassini spacecraft, soon ending its 13 years orbiting Saturn, has sent back another spectacular image of Saturn's immense ring system in unprecedented detail. The physical cause for some of Saturn's ring structures is not always understood. The cause for the beautifully geometric type of ring structure shown here in ring of Saturn, however, is surely a density wave. A small moon systematically perturbing the orbits of ring particles circling Saturn at slightly different distances causes such a density wave bunching. Also visible on the lower right of the image is a bending wave, a vertical wave in ring particles also caused by the gravity of a nearby moon. Cassini's final orbits are allowing a series of novel scientific measurements and images of the Solar System's most grand ring system.

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[Boomer12k]

Wonderful, and interesting... it is wavy...

The 21st is supposed to be clear, around 84 degrees F...29C... hope to get some good video of the Eclipse.

I think my DSI camera would be too close a view through the scope... But will be fine with my Samsung F40...and Tripod...

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[Gaplets]

When Galileo said that Saturn has handles, he meant that it just looked like that. When we say that Saturn has a disk, we don't mean that it is one solid body like Huygens thought.
When we say that Saturn has rings, we do not mean that they are annular and concentric. When we say that Saturn has ringlets, we again do not mean that they are annular and concentric.
When we say that Saturn has spiral waves, we do not mean that the waves are carrying material into Saturn or to its moons. When we say Saturn has spiral waves, we mean that it has both spiral bending waves and spiral density waves.

See https://www.researchgate.net/post/What_ ... _in_Saturn

[neufer]

The 21st is supposed to be clear, around 84 degrees F...29C... hope to get some good video of the Eclipse.

• A 13 day forecast (Farmer's Almanac )

[MarkBour]

Beautiful image. It does indeed give the illusion of "curvature" in the rings (going out radially from Saturn, not the main circular curvature itself), on two scales at least: Each small band looks almost like it is a curve (like corrugations) and the overall image appears as though it has a larger wave shape, with about 3 periods going across the entire image. That larger wave also can look like a larger curvature, like sand dunes, to the human mind/eye out of context.

If I understand correctly, though, Saturn's rings are indeed amazingly thin and flat. So all of the beautiful variations in this image between dark and light are caused by there being more or less material. More material, lighter band, less material, darker. And these changes, which I do think are visible on two distinct scales, can be called density waves (like sound waves). I don't know if that is the exact meaning Professor Nemiroff has when he says "density waves" in the caption. And I wonder if we would see the wave patterns repeated with any similarity in other ringed exoplanets, or if the kind of density waves that occur are essentially the result of randomness and many contributing factors.

[heehaw]

Glorious!

[steve wiggins]

The Cassinni spacecraft mission is ending soon and was highly successful! With all the trouble taken to keep Cassinni's 70 lbs of plutonium fuel out of Earth's biosphere, we should also take precautions to keep it off of Saturn! It's not too late too do so. Act now. Write your congress person. We don't know what effect this could have. At any rate it doesn't set a good precedent for our exploration of space.

[Chris Peterson]

The Cassinni spacecraft mission is ending soon and was highly successful! With all the trouble taken to keep Cassinni's 70 lbs of plutonium fuel out of Earth's biosphere, we should also take precautions to keep it off of Saturn! It's not too late too do so. Act now. Write your congress person. We don't know what effect this could have. At any rate it doesn't set a good precedent for our exploration of space.

Rubbish.

[geckzilla]

The Cassinni spacecraft mission is ending soon and was highly successful! With all the trouble taken to keep Cassinni's 70 lbs of plutonium fuel out of Earth's biosphere, we should also take precautions to keep it off of Saturn! It's not too late too do so. Act now. Write your congress person. We don't know what effect this could have. At any rate it doesn't set a good precedent for our exploration of space.

We've been over this time and time again. For any not following: Cassini's fuel and other possible biological contaminants are being directed into Saturn's atmosphere, where they will disintegrate, keeping the many interesting and varied satellites of Saturn safe from contamination with no known negative consequences to Saturn itself. There is no way to bring Cassini out of the Saturn system, and leaving it in orbit would likely result in an eventual collision with one of the moons, which would create a cloud of debris that would unpredictably contaminate other bodies in orbit. The consequences of this alternative are far worse than de-orbiting Cassini into the atmosphere of Saturn.

[heehaw]

The Cassinni spacecraft mission is ending soon and was highly successful! With all the trouble taken to keep Cassinni's 70 lbs of plutonium fuel out of Earth's biosphere, we should also take precautions to keep it off of Saturn! It's not too late too do so. Act now. Write your congress person. We don't know what effect this could have. At any rate it doesn't set a good precedent for our exploration of space.

There is some natural Plutonium on Earth: https://www.scientificamerican.com/arti ... lements-s/ which surely means that there is natural Plutonium already in Saturn. But maybe not high up in the atmosphere of Saturn, of course! Suppose there is some aerial form of life in Saturn's atmosphere: could there be a range of altitudes where pressure and temperature are suitable for life, and perhaps life developed over billions of years? Why is Saturn so colorless compared with Jupiter? Maybe Saturnine bugs eat the colorful stuff. Maybe we'll destroy all that life with our Plutonium love note. Keep a close eye on Saturn over the next few decades: if colors develop, well, I did warn you! Of course what I am saying is rubbish.

[Chris Peterson]

The Cassinni spacecraft mission is ending soon and was highly successful! With all the trouble taken to keep Cassinni's 70 lbs of plutonium fuel out of Earth's biosphere, we should also take precautions to keep it off of Saturn! It's not too late too do so. Act now. Write your congress person. We don't know what effect this could have. At any rate it doesn't set a good precedent for our exploration of space.

There is some natural Plutonium on Earth: https://www.scientificamerican.com/arti ... lements-s/ which surely means that there is natural Plutonium already in Saturn. But maybe not high up in the atmosphere of Saturn, of course! Suppose there is some aerial form of life in Saturn's atmosphere: could there be a range of altitudes where pressure and temperature are suitable for life, and perhaps life developed over billions of years? Why is Saturn so colorless compared with Jupiter? Maybe Saturnine bugs eat the colorful stuff. Maybe we'll destroy all that life with our Plutonium love note. Keep a close eye on Saturn over the next few decades: if colors develop, well, I did warn you! Of course what I am saying is rubbish.

Even allowing for life, the reality is that the 23 kg of Pu-238 aboard Cassini could burn up in Earth's atmosphere and the impact on our biosystem would be undetectable. It has a short half-life, and is only an alpha-emitter. There's no reason to assume it would be toxic to any life there, even disregarding the absurdly low concentration and the likelihood that naturally occurring plutonium (and it does occur naturally) is already present in greater amounts.

[Boomer12k]

The 21st is supposed to be clear, around 84 degrees F...29C... hope to get some good video of the Eclipse.

• A 13 day forecast (Farmer's Almanac )

14 day forecast on Tablet....

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[neufer]

The 21st is supposed to be clear, around 84 degrees F...29C... hope to get some good video of the Eclipse.

• A 13 day forecast (Farmer's Almanac )

14 day forecast on Tablet....

• I'd average the 3 days from the 20th to the 22nd rather than betting on the 21st.

[workgazer]

The Cassinni spacecraft mission is ending soon and was highly successful! With all the trouble taken to keep Cassinni's 70 lbs of plutonium fuel out of Earth's biosphere, we should also take precautions to keep it off of Saturn! It's not too late too do so. Act now. Write your congress person. We don't know what effect this could have. At any rate it doesn't set a good precedent for our exploration of space.

Rubbish.

Best most sucink point ever made by chis , pure genius.