Ice moon, ghost moon

Contributed by
May 10, 2012
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One of my favorite things to do is take a gorgeous astronomical image and pierce down into it, finding some detail not discussed in press releases and other articles.

On the other hand, sometimes I'll post a picture because it's so, so cool:

[Click to encronosenate.]

That's a shot of Saturn's rings and moons by the Cassini spacecraft, taken in mid-April 2012. Cassini was nearly in the same plane as the rings, so they look like a knife cutting across the image. The bright moon is Enceladus, tiny and icy, almost but not quite full as seen from this angle.

But the scene stealer is Titan, the moon as big as a planet -- bigger than Mercury, actually -- looming in the background, nearly invisible. This image, taken using a filter that only lets through green light, shows just how much darker Titan is than Enceladus. The bigger moon is shrouded in a thick, hazy atmosphere, and reflects about 1/5th of the sunlight that falls on it. Enceladus, on the other hand, is covered in ice, and reflects nearly all the light that falls on it. So the brightness ratio you see here is real: Titan really is far darker then Enceladus.

... and there you go. I drilled down a bit into the picture's science anyway. I guess I had to. It's in my nature; when it comes to science, I'm reflective too.

Image credit: NASA/JPL-Caltech/Space Science Institute


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- An icy Titanic encounter
- Enceladus fires on Alderaan
- Incredible quadruple transit on Saturn!
- The scale of Saturn