A lunar eclipse offers one of two ways of observing the Earth's shadow. On very clear mornings and evenings, about 15 minutes before sunrise or after sunset, you can see the earth's shadow, as shown below. The blue area is the Earth's shadow. Superimposed on the photo is a photograph of the partially eclipsed moon from Aug 28, 2007. Notice a similarity of color along the shadow's edge.

When fully eclipsed, the moon shows a deep red color: