During a total lunar eclipse the shadow of the Earth will cross gradually over the surface of the moon, but once the moon has entered the umbra, completly blocking the sun's light, the moon will often look reddish.

在月食的整个过程中，地球阴影会逐渐扫过月球表面，但是一旦月球进入地球暗影完全接收不到太阳光，月球通常看起来会是淡红色。