Jun. 28th, 2005

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Continuing its free Beethoven symphony series, the BBC has the Sixth (Pastoral) and Seventh Symphonies up for download. Eight and Nine are on the way...
mmcirvin: (Default)
When I first saw these raw images from Cassini, I thought they were pictures of the Sun seen through the rings. But they're not; that's the sunlit side, and the bright spot is brightest where the rings are most opaque (you can see the spot fading out as the view shifts to the more transparent C ring). Actually, I think it's a kind of heiligenschein caused by the shadow opposition effect. Like the lunar soil around the astronaut's shadow, the rings of Saturn are made of many small particles ("small" here meaning house-sized and smaller), and in the thickest and most opaque part of the rings, they cast shadows on each other. But when you look from the direction of the sun, the particles block the view of their own shadows, and it creates a region of greater apparent brightness around the anti-solar point.

(I suppose this kind is technically not heiligenschein, since it doesn't involve internal reflection scattered refraction in spherical droplets, but I like saying "heiligenschein").

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