Total Eclipse of the Heart

Tonight is the first winter solstice lunar eclipse in centuries.  Currently, my students are talking about the moon and its phases in science class.  One of my students was very excited when he came over to see me after science.

"Did you know there's a lunar eclipse tonight?" Herman asked me, "The moon will be red and everything."

"What makes it red?" I asked him.

"I don't know.  It must be embarassed 'cause everyone's looking at it or something." he replied.