F ring and Mimas

F ring and Mimas

F ring and Mimas

Bad Astronomy
The entire universe in blog form
Jan. 2 2008 7:06 PM

F ring and Mimas

Regular readers know that

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

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  • I love Saturn,
  • I love Emily, and
  • I love optical illusions.
  • So when you have Emily posting on an illusion dealing with Saturn's rings, you know you're onto something pretty cool.

    See how the ring looks darker where it crosses the moon Mimas than when you see it over a dark background? Emily checked, and the ring pixel values are actually higher there!

    I suspect Emily's conclusion is correct; light from Mimas is coming through the ring, adding to its pixel value. But the rest of Mimas is so bright that the ring looks dark compared it it. That's an odd illusion, but a well-known one.