The phenomenon that occurs when the sun blocks the moon is called a lunar eclipse. This event happens when the Earth comes between the sun and the moon, casting a shadow on the moon's surface. A lunar eclipse can occur only during a full moon and can be total, partial, or penumbral, depending on the alignment of the Earth, moon, and sun. During a total lunar eclipse, the moon may appear reddish, a phenomenon often referred to as a "blood moon," due to the scattering of sunlight through the Earth's atmosphere. Lunar eclipses are fascinating celestial events that can be observed from anywhere on the night side of the Earth.