The unlit side of the rings Options

[Bjorn Jonsson]

Cassini has previously imaged the unlit side of the rings but now it is doing extensive observations of the unlit side. For the first time in its mission Cassini is spending a significant amount of time north of the ringplane - earlier it has done so only near periapsis but this orbit is different.

This is a quick RGB composite I did from wide angle images:



I made no attempts to correct the color - this is probably not very far from the true color of the rings. Large color variations are apparent, the C ring and the Cassini division appear much more bluish than the thicker rings (A and B ). It should be noted that these images were very probably downliked with the 12 -> 8 bit encoding which basically means that dark areas appear too bright in this image because I did not correct for this.

It's also interesting to compare this image to Voyager images:

Voyager 1: http://photojournal.jpl.nasa.gov/catalog/PIA02241

Voyager 2: http://photojournal.jpl.nasa.gov/catalog/PIA01955
Voyager 2: http://photojournal.jpl.nasa.gov/catalog/PIA01389

[alan]

Get your images stitchers ready

Saturn's Rings To Shine As Never Before
September 15, 2006
(Source: Jet Propulsion Laboratory)

Ring scientists have been waiting for this. Finally, after more than two years orbiting Saturn, the Cassini spacecraft reaches one of the ultimate vantage points. The rings should shine with majesty worthy of the "Jewel of the Solar System."
The event is a solar occultation -- when the sun passes directly behind the planet as Cassini looks on. And this is not just any solar occultation; it's a very long one. The Cassini spacecraft will be right where scientists studying the rings want it: far enough from Saturn to be able to image it all and, more importantly, with the Sun blocked by the planet for 12 hours, long enough to properly map the elusive microscopic particles moving within the extended ring system.
Data collected during this observation might also uncover clues about Enceladus' past behavior and aid mission planners in refining ring hazard models for future ring crossings. Thanks to the slow occultation, images taken during this carefully designed orbit may also uncover new ring structures and, at the very least, capture truly spectacular views of the D, F, G and E rings.
"We are all sort of on pins and needles waiting for the results," says Brad Wallis, Cassini Rings Discipline Scientist. "When you get these kinds of high phase angles, very small particles almost focus the light right at the observer. So these faint rings that are so hard to see are going to be considerably brighter and show us details that are just not possible to see in other viewing conditions. All the space between Enceladus and the G ring is probably going to be pretty well lit up. It's really a unique event.'

http://saturn.jpl.nasa.gov/news/features/feature20060915.cfm

[dilo]

Get your images stitchers ready
http://saturn.jpl.nasa.gov/news/features/feature20060915.cfm

Amazing!
Hope they will take also a snapshot of Earth trough A-ring...

[ugordan]

Nice view:

[mchan]

That deserves a wow! Can't figure out the lighting geometry...

[ugordan]

The viewing geometry is similar to the solar occultation sequence last orbit. Cassini's above the ring plane, the sun is below and located at about upper left position. Everything you see is Saturn's nightside and the unlit rings. Saturn's north is to the top. It's striking that while Saturn's southern hemisphere is lit by light reflected off the rings, even the northern latitudes are lit near the terminator by the light forward scattering through the rings. This illumination is noticeably more bluish, probably the effect of the ring particles preferentially forward scattering shorter wavelengths.

[mchan]

...Saturn's southern hemisphere is lit by light reflected off the rings...

D'oh! I was thinking how there could be a terminator across Saturn when the planet shadow cuts across the rings like that...