A total lunar eclipse occurs when the Moon travels entirely through the Earth's shadow. When the Moon goes through part of the Earth's shadow, a partial eclipse is observed.
For a total eclipse to be seen, the Earth, Moon and Sun must be in perfect alignment. The Moon often takes on a reddish tint during a total eclipse because a small amount of sunlight creeps around the edges of the Earth and reflects off the surface of the Moon, creating the appearance of a blood-red moon. Before humans understood the science behind an eclipse, this rare event sparked fear and confusion.