The Moon


[In answer to a question is it full moon everywhere in the world at the same time?- see LETTERS]

Good question … but it IS Full Moon over the world, at one moment, Lara.

In theory, the Moon will look slightly different from different parts of our planet (and of course there will be places from which it’s below the horizon) but Astronomers designate Full Moon as the moment when the centres of the Earth and the Moon and the Sun are closest to fitting on a straight line (with the Earth in the middle).

New Moon is similarly defined as the moment when the three bodies are closest to alignment too, but in this case the Moon is between the Earth and the Sun. It’s interesting to notice that, in this astronomical definition of NEW MOON – the Moon is not visible at all in the night sky. But in common parlance, the thin crescent which appears just a day or two afterwards in the evening twilight, is called a New Moon. Confusing, isn’t it ! Just to add to the muddle, Astronomers call the ‘Half Moon’ – which comes two weeks after ‘New’ phase – FIRST QUARTER !

By the way, I say ‘closest to’ alignment, because, of course, on those occasions when the three bodies are exactly in the same plane, we get a perfect alignment – and that’s when eclipses happen.