Thursday, June 01, 2006
Shadow of the Rings
This image was taken about a month ago as Cassini looked back on Saturn's northern hemisphere. According to mission scientists:
It is unlikely that the shadows cast by Saturn's rings have much of an effect on the large-scale movements of the atmosphere. The dynamic clouds of this gas giant are driven by processes going on much deeper inside the planet, where sunlight does not penetrate.
They seem to have a chemical effect, though. You can't see it from Earth, but the cloud tops of the shadowed north seem to be cooled just enough to appear blue, as you can see below from this color image taken a year ago.
Neptune's blue color is attributed to methane gas at just the right temperature, about 2 billion miles farther out from the sun. Blue clouds were not expected at Saturn.
I haven't seen a fully scientific explanation for this yet.
NASA goofs badly with an explanation about "blue skies" on this site. The color of sky is determined by looking up at them, not down on them. The scientist is right, though that skies on Saturn are probably blue. But definitely not because they appear blue from above.
