One of the ways in which fundamentalist Christians like to make the argument that God created a perfect universe for mankind to live in is the position of the Moon in relation to the Earth and the Sun, which is most obvious during a total eclipse. When you see a total eclipse, the Moon appears to completely cover the Sun, ie the Moon is exactly the right size and distance from the Earth to give this effect:

How could it be a coincidence that the Moon is just the right size, and just the right distance away? What are the chances that this could just happen? Surely God must have made it that way?

I'll ignore the obvious point about chance: by chance, yes, it obviously could happen. But there is something perhaps less well known about eclipses. The Moon doesn't always cover the full disc of the Sun. I'm not talking about a partial eclipse, where only a segment of the Moon blocks out part of the Sun. I'm talking about a situation where the whole of the Moon is in front of the Sun but is not big enough to block out the whole of the Sun. This is what is known as an annular eclipse.

Annular is nothing to do with 'annual' (ie yearly), but is from the word annulus, the Latin for 'ring', and this picture (multiple exposures show the Moon as it passes over the sun) will explain why it has been given this name:

Explanation? The Moon's orbit is not perfectly circular. It is in fact elliptical, which means that sometimes the Moon is further away from the Earth, sometimes closer. During an annular eclipse the Moon's orbit takes it further away, so that it appears smaller, and so does not cover the full disc of the Sun. Instead it leaves a thick ring (annulus) of visible Sun. You may be less familiar with this type of eclipse because it is, naturally, less dramatic than a total eclipse, which blocks out the entire Sun and, as in the first picture, allows the dramatic corona of the Sun to become visible. This is not the case with annular eclipses, which is perhaps why they receive less TV time.

So this is by no means a God-given 'perfect' situation. The next time someone tells you that God put the moon just in the right place to create a total eclipse, explain that the Moon's orbit is elliptical, that sometimes it appears to be smaller in the sky, because it is further away, sometimes larger because it is closer. Annular eclipses show that the eclipsing effect of the Moon passing in front of the Sun is not always perfect. And another 'proof of God's design' bites the dust.

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Footnote:
Annular eclipses are more common than total eclipses. About one in three eclipses (32.9%) are annular. Only about one in four (26.6%) are total. See this page for more information about the different types of eclipse.