An eclipse of the moon occurs when the earth comes between the moon and the sun. During a lunar eclipse, the Earth blocks the sun's light from directly reaching the moon. Instead, the Earth's shadow falls on the moon, causing it to appear reddish-brown or orange in color. This happens because some of the sunlight passing through the Earth's atmosphere is scattered and refracted, so that longer-wavelength light (like red and orange) is more likely to reach the moon.