A lunar eclipse occurs when the Earth passes between the Sun and the Moon, causing the Earth's shadow to fall on the Moon. This can only happen during a full moon when the three celestial bodies are aligned. There are three types of lunar eclipses: total, partial, and penumbral, depending on how much of the Moon enters the Earth's shadow. During a total lunar eclipse, the entire Moon can appear reddish due to sunlight scattering through the Earth's atmosphere, a phenomenon often referred to as a "blood moon." Lunar eclipses are safe to view with the naked eye and can be observed from anywhere on the night side of the Earth.