Why does the Moon look red during an eclipse?
The Moon usually looks white because it’s reflecting white light from the Sun. It doesn’t have an atmosphere, so there’s no air or dust to filter the light and change its colour. If terra-lunar geometry was more thoroughly thought out, we’d have a total lunar eclipse every full Moon. Pic: NASA But during a total eclipse the only light that reaches the Moon has already been filtered by the Earth’s atmosphere. Once light hits all that gas and dust, it gets scattered. Long wavelength reddish light tends to bounce right out into space – it’s the light that reaches the Moon. Shorter wavelength blue light keeps bouncing around off molecules and doesn’t really get a chance to escape. (That’s why the sky usually looks blue – the red light bounces away, so blue is all that’s left). How come we can look directly at a lunar eclipse? The Moon’s light is only ever reflected from the Sun, so it’s never all that bright. And during a lunar eclipse you’re seeing a smaller amount of even dimmer reflecte
