A couple of nights ago (mornings actually) there was a lunar eclipse that resulted in a red moon. My students were alerted to the fact so got up early to have a look. One of them, Alberto, took this great photo. I didn't know it was going to happen but got up anyway to take the dog out. Wow, what's that big red moon all about. Students asked me what caused it so I made something up about it being the same thing that makes sunsets red. The blue light is scattered leaving red that is refracted by the atmosphere into the shadow of the Earth. Turns out to be right.

Here is an Algodoo simulation to show how the refraction works.