Question

During a lunar eclipse the mood is not completely dark, but it is often a deep red in color. Explain this in terms of the refraction of all the sunsets and sunrises around the world.

Answer 1

The Moon does not completely disappear as it passes through the umbra because of the refraction of sunlight by the Earth's atmosphere into the shadow cone; if the Earth had no atmosphere, the Moon would be completely dark during an eclipse. The red colouring arises because sunlight reaching the Moon must pass through a long and dense layer of the Earth's atmosphere, where it is scattered. Shorter wavelengths are more likely to be scattered by the small particles, and so by the time the light has passed through the atmosphere, the longer wavelengths dominate. This resulting light we perceive as red. This is the same effect that causes sunsets and sunrises to turn the sky a reddish color; an alternative way of considering the problem is to realise that, as viewed from the Moon, the Sun would appear to be setting (or rising) behind the Earth.

Answer 2

The answer to this question is the same as the answer to why is the sky blue? Refraction or the suns rays causes blue light to pass straight down to the earth. Red light does not come straight down. that is why sunset and sunrise is red. 

This red light hits the moon during eclipses that are near blackouts of the moon