dpA lunar eclipse happens when the Earth passes between the Sun and the Moon, causing the Moon to temporarily move into the Earth’s shadow.
During a partial eclipse, only part of the Moon enters the darkest section of that shadow, known as the umbra.
The Moon is not completely cut off from sunlight, however.
Sunlight passing through the Earth’s atmosphere is scattered, with shorter blue wavelengths scattering more easily, while more of the longer wavelength red light reach the Moon.
These wavelengths are then reflected back towards Earth, giving the eclipsed Moon its reddish colour.
