What is a lunar eclipse?

A lunar eclipse occurs when the Moon enters the Earth’s shadow. AN graphic by Greg Smye-Rumsby.

Just as the Moon’s shadow can create a solar eclipse on Earth, the Earth can cast a shadow onto the Moon, creating a lunar eclipse, which are breath-taking in their own way.

As the full Moon passes into the Earth’s shadow, the surface of the Moon darkens and, at maximum eclipse, the Moon changes colour to a deep red, rather than vanishing altogether. The reason this happens is that, even though the Earth is completely blocking out the Sun’s light over the whole face of the Moon, rays from the Sun are bent (refracted) in the Earth’s atmosphere, and can illuminate the Moon.

The red light from the Sun’s spectrum is what illuminates the Moon during a total lunar eclipse, turning the Moon red: you are seeing the light from every sunrise and sun set on Earth reflecting off the Moon. Lunar eclipses are more common than solar eclipses

Steve Owens