Earth and beyond

our Moon

phases of the Moon

what is a lunar eclipse?

the coloured Moon

the Moon's vital statistics

the coloured Moon

Even though the Moon is in the Earth's shadow during a lunar eclipse, some red sunlight is able to get to the Moon by being bent through the Earth's atmosphere. So during an eclipse, the Moon does not disappear in black shadow, but instead turns a dark red.

Here's a photograph showing this effect. The light from the Sun is scattered by the Earth's atmosphere.

Blue light is scattered in all directions much more than red light. This means that if the light travels a long distance through the atmosphere, it will be mostly the red light that reaches the Moon.

Image of the Moon

Picture taken by South African Astronomical Observatory.

There’s an expression that we use to describe an event that happens very rarely - ‘Once in a blue Moon’.

Can I see a blue Moon?
A modern definition is that a blue Moon is the second of two full moons that appear in a single calendar month. This can happen because the lunar cycle is shorter than any calendar month.

['Once in a blue Moon' Does the Moon realy go blue? - Yes, there are very rare reports of the Moon actually looking blue! This was probably the result of some strange condition in the Earth's atmosphere.]

According to this description, the next blue Moon will be at the end of June 2007 (full Moons occur on 1st and 30th June). Clearly, it's something that doesn't happen very often, but is unlikely to be actually blue!



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