Starship Asterisk*

orin stepanek wrote:*ONION RING*

Twas a chicken dinar in a neighboring city that gave you an order of onion rings that filled your plate and were heaped up about 8". Whenever we were in that fair city we loved to go there for a snack. One plate sufficed to satisfy 4 or 5 friends. They weren't as pretty as Saturn's rings but were very delicious.

orin stepanek wrote:All of Sol's giants have rings. I wonder if this is the norm?
And why does Saturn have the most grandiose rings of all.
Anyway Saturn has the best custom at the ball

• *NO IRONING*
  *ONION RING*

emc wrote:I’m guessing Jupiter ate most of its rings, Saturn had less of an appetite

http://en.wikipedia.org/wiki/Onion_ring wrote:
<<ONION RINGs are a type of fast food commonly found in the United States, Canada, United Kingdom, Australia, and some parts of Asia. It generally consists of a small ring of onion dipped in batter or bread crumbs and then deep fried. The result varies from restaurant to restaurant. The ring-like structure of an onion lends itself well to this mode of preparation. A variant of this is made with onion paste and there are advantages and disadvantages between the two. Whole onion rings make for better presentation through a variety of sizes, while those made from a paste offer quantity through consistent size. Consumers of whole onion rings run the risk of pulling the onion out of the batter if they fail to cut it all the way through with their teeth, while onion rings made of onion paste break apart easily but oil absorbency diminishes the onion taste.

The exact origins of the onion ring is unknown, but in 1933 a recipe for deep-fried onion rings that are dipped in milk then dredged in flour appeared in a Crisco advertisement in The New York Times Magazine.>>

orin stepanek wrote:All of Sol's giants have rings. I wonder if this is the norm? And why does Saturn have the most grandiose rings of all. Anyway Saturn has the best custom at the ball; though Earth is the prettiest.

jerbil wrote:I see your point that local instability within a ring does not imply the destruction of the ring. A Shoemaker-Levi would not even dent a ring's survival, however spectacular was its impact on Jupiter. So, how did Saturn's rings develop? We know from one of the Voyager missions that Uranus has a faint ring system, but if this arises from the origin of our solar system, then why does not Jupiter possess one? Perhaps, as I have read, at an earlier stage, when there were many more rogue objects in the locality there were two catastrophic collisions in the neighborhood of each planet.

Chris Peterson wrote:

jerbil wrote:There are certainly unstable regions within the rings- that's why the structure is so complex, with its gaps and density variations. It seems perfectly reasonable that right at boundaries between stable and unstable zones you should see odd effects, such as the frills you mention. I don't see how this reflects on the stability of the ring system as a whole, however.

jerbil wrote:There is, however, a further comment I would like to make on the stability in the long term of the ring system around Saturn. As has been noted in at least one previous APOD contribution, a detailed analysis of the edges of the ring systems note "frilling," namely that the inner and outer limits of a particular ring are not smooth.

There may be resonance conditions which explain this, which would require Fourier analysis to confirm (or reject.) If some sort of a wave pattern is not established for the effect, I would suggest that this observation would add further evidence for the instability of the ring system as a whole.

3uu2 wrote:Question: why does the moon on the middle left of the outer ring (Janus?) not cast a stripe shadow across the rings or make a spot shadow on the clouds near the ring shadow? There must be a shadow but I can't see it.

Chris Peterson wrote:

jerbil wrote:I find this magnificent composite photograph extremely difficult to interpret. I presume that the ring system and the accompanying shepherd moonlets are coplanar, so that at equinox they contribute a single dark line of shadow on the upper Saturnian cloud layer.

That's correct.

Underneath what I interpret as this line, there are numerous other shadow lines, at least as strong, which I can only put down from the description of the photograph as the "elongated shadows" from out-of-plane objects, though why they should be so strong escapes me, as does the fact that they are grouped together.

All of the lines below the ring shadow are just silhouettes of the rings themselves. They are not shadows on the cloud tops.

jerbil wrote:I disagree. The observed striations, sometimes called spokes, seen on many of the other Cassini photographs, indicate that the ring system, despite the efforts of shepherd moonlets, is inherently unstable. My earlier understanding of gravitational dynamics was that, on any astronomical timescale, a ring system such as that of Saturn would be "short-lived."

jerbil wrote:I find this magnificent composite photograph extremely difficult to interpret. I presume that the ring system and the accompanying shepherd moonlets are coplanar, so that at equinox they contribute a single dark line of shadow on the upper Saturnian cloud layer.

Underneath what I interpret as this line, there are numerous other shadow lines, at least as strong, which I can only put down from the description of the photograph as the "elongated shadows" from out-of-plane objects, though why they should be so strong escapes me, as does the fact that they are grouped together.

Furthermore, to the far right and at the immediate bottom of the image, there are bright arcs, while the insolation clearly comes from the left.

NoelC wrote:My understanding (shored-up by last night's repeat of The Universe) is that orbital mechanics sufficiently explain why the particles keep from coaslescing. The particles at different distances from the planet simply orbit at different speeds.

I've always wanted to see a time lapse of the rings to make that clear. I imagine the dynamics, even from a long way off, would be spectacular to watch.

-Noel

Craine wrote:There seem to be a number of moonlets visible in and around the rings. Some are clearly moonlets as they obviously disturb the nearby rings. But others could be bright background stars. I'd rather think the overall brightness might fade out any background stars though, I am not sure. Anybody wanna comment? Or perhaps somebody can even name the moonlets we can see?

The moon Janus (179 kilometers, 111 miles across) is on the lower left of this image. Epimetheus (113 kilometers, 70 miles across) appears near the middle bottom. Pandora (81 kilometers, 50 miles across) orbits outside the rings on the right of the image. The small moon Atlas (30 kilometers, 19 miles across) orbits inside the thin F ring on the right of the image. The brightnesses of all the moons, relative to the planet, have been enhanced between 30 and 60 times to make them more easily visible. Other bright specks are background stars. Spokes -- ghostly radial markings on the B ring -- are visible on the right of the image.

orin stepanek wrote:I'd say the rings were dark because the sun can't light them up. ...

The novel illumination geometry that accompanies equinox lowers the sun’s angle to the ring plane, significantly darkens the rings....
At this time so close to equinox, illumination of the rings by sunlight reflected off the planet vastly dominates any meager sunlight falling on the rings. Hence, the half of the rings on the left illuminated by planetshine is, before processing, much brighter than the half of the rings on the right. On the right, it is only the vertically extended parts of the rings that catch any substantial sunlight.
With no enhancement, the rings would be essentially invisible in this mosaic. To improve their visibility, the dark (right) half of the rings has been brightened relative to the brighter (left) half by a factor of three, and then the whole ring system has been brightened by a factor of 20 relative to the planet. So the dark half of the rings is 60 times brighter, and the bright half 20 times brighter, than they would have appeared if the entire system, planet included, could have been captured in a single image.

Fortunately...humanity is advanced enough to have a spacecraft that can see the rings during equinox from the side.