Will we have enough time to watch the next wave pop up before edge-on is over?

Question: Could these be considered standing waves, or maybe even solitons? They look pretty stable in that sequence.

Also, I suspect that their structure is more complicated than they look here. Been visualizing something like a polarized radar pulse with a third dimension & a helical component.

I'd like to perform some basic calculations of aproximate elevations of some moonlets and waves above the ring plane. The problem is that the position of Cassini spacecraft relative to Saturn & Sun is needed, and that requires the hour of the day the individual Cassini images were shot. Info released along with Cassini images only comprise the day, but not the hour within the day. ¿is there any way to know the hour-of-the-day info of the moment a given image was shot by Cassini?

For really intelligent answers to a lot of questions raised on this thread, see the great entry on Emily's Planetary Society Blog by guest blogger David Seal. Wow!

All that information (image time to the second) is in the PDS headers, which you can get when the validated data is released for scientific work.

The raw images do give an approximate distance to the RINGS, so that information can in principle be combined with an ephemeris to yield the time. I've had some luck doing this with raw images of the satellites. Backing out the times of ring images might be trickier as it's unclear to me which part of the rings (or Saturn) is referenced in the distance.

Two months before the equinox game of light and shadow reveals more and more details. On these pictures clearly seen that the edge of the ring extends above the plane of the ring.
http://saturn.jpl.nasa.gov/multimedia/imag...0/N00137394.jpg
http://saturn.jpl.nasa.gov/multimedia/imag...0/N00137396.jpg

Interestinger and interestinger. I'm really looking forward to the equinox - the next four or five Titan encounters pump Cassini's ringplane inclination down to below 20 degrees in August/September, and periapse goes from 570,000km currently, to half that distance in August/September - literally a ringside seat!
Can't wait!

Does anyone know at what point the rings will go dark and how long they'll stay dark? Or is that among the things we're expectingg to learn?

--Greg

They won't get completely dark because Saturn will still be illuminating them from both sides. They will get pretty dark, though, but probably only close to the actual plane crossing.

Thanks. I went and read the suggested post on Emily's blog and figured that out too, but I was too late to edit my original. :-)

It does surprise me that the reflected light from Saturn has such a strong effect, though. I'd expect it to be just a few percent of solar illumination. (I'm too lazy to work it out right this second, but it's obvious that at some amount of tilt, the two are equal.)

--Greg

Greg, I'm sure you're after more accurate information, but I did give a rough calculation in post 72 of this thread which may be of some interest (in case you missed it). I assumed a solar elevation angle of between 1 and 2 degrees there.

I did miss it, but it's quite interesting. I note that I match some of your numbers, coming at it from a different angle. I start by picking a point in the B ring (near the inner edge) where Saturn subtends exactly 60 degrees. That means it covers 6.7% of the sky. Since Saturn has a geometric albedo of 0.47, it'd be 47% as bright as the sun if it were a sheet covering half the sky. Hence our ring particle ought to get 6.3% as much light from Saturn (the whole planet) as it does from the Sun -- assuming nothing else is in the way. I think this is very close to the number you got for this part of the problem.

But the other parts of the ring do get in the way, and we can assume that the illumination from the Sun drops as the sine of the ring tilt. (Or cosine if we're talking angle of illumination, I guess.) But we should make the same assumption for the light from Saturn itself, right? Saturn's equator doesn't illuminate the rings at all, but as you go further north or south, the amount of illumination increases -- except, of course, the planet narrows too. I don't feel like setting that integral up tonight, but I'm guessing it'll drop the Saturnshine component by about a factor of 5. (And that's constant, of course; it doesn't depend on the ring tilt). At that point we can figure out the point where solar illumination drops below illumination by Saturn.

Again, I'm saying "ring tilt" to refer to the angle between the ring plane and a line connecting Saturn and the Sun.

Sound right so far?

--Greg

Okay, I think I've worked it out. I think the only naive assumption is that Saturn's disk is equally bright, even though we know there ought to be at least some limb darkening.

So using the logic above, I come up with 1.6 degrees. That is, when the rings are within 1.6 degrees of the vector to the sun, the solar illumination and the "Saturnshine" should be equal. We'd have reached that point on April 28. Of course, my naive assumption overstates how bright the Saturnshine is.

This agrees fairly well with the estimate in post 72, particularly when you consider that I've chosen a point a good bit closer to Saturn.

Summary: I think it's fair to say that by now at least the inner rings are more brightly lit by Saturn than by direct sunlight. Of course, this effect diminishes as you go around the planet, so the view from above should already show the rings being a good bit brighter in front of Saturn, getting darker as they approach the shadow in the back, and with this effect more pronounced for the inner rings. Does anyone have a pic of that?

--Greg

this one shows that effect, although I not sure it is not showing the side not directly lit by the sun

http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=191742

edit : Ooo, triple negative, have fun parsing that