The Underscore Archives

on 5/3/07 11:54, Mark Chitty at mark.chitty at gmail.com wrote:

> That is good!
> 
> Only caught the first half on Saturday but it was really impressive. I
> always wonder whether the reddening only appears as your eyes get used to
> the light levels as the bright bit disappears.

I believe the accepted explanation is the same as a sunset being red.

The reason is that over a large amount of atmosphere (such as when the sun
is low in the sky) the blue all gets scattered away, leaving just red light.
If you imagine standing on the moon during an eclipse, you'd effectively see
a red ring around the earth, since there'd effectively be a sunset all the
way round it.

Since this red light makes up the majority of the light hitting the moon, it
appears red. The more pollution in the earth's atmosphere, the redder the
light.

Oliver.