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Sunday, November 17, 2013
Saturn and Other Planets
CICLOPS released this picture a few days ago. It purports to show four (count 'em, 4!) planets: Saturn, Earth, Mars & Venus. Only Saturn is visible here, the other three have been reduced to non-existence by virtue of their sub-pixel dimensions. You can see them as blue dots in the full size image.
What I don't understand is what is showing on the face of the planet? Why is it not just completely black? And why is there a black band outside the upper half of the bright ring around the planet? The bright ring I suspect is sunlight being refracted through the upper layers of Saturn's atmosphere.
Half of the press on this seems to be playing up the business of all the people on Earth waving at Saturn to have their picture taken (last summer). That's the dumbest thing I ever heard, and that's why I'm not the president of anything, just in case you were wondering.
Update: Just discovered that I put up a post on this topic a couple of months ago.
You are very observant, noting the weird things that happen with lighting on Saturn's rings. The back side of Saturn is not dark because it is illuminated by light reflected off the rings. Note that at the equator it is dark because there the rings are seen edge on and send no light down to the planet. The rings appear not to line up because in the middle the rings are in shadow and you are seeing them through transmitted light. The rest of the rings are illuminated by the sun and you are seeing scattered light. The different thicknesses of ring material act very different in these different lighting situations. This would be a lot easier to explain in person with a laser pointer!
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