Tuesday, February 14, 2006

On the moon

The Moon is a pretty unusual satellite.

Firstly, it's very big – the Moon-Earth size ratio is much higher than say the Phobos-Mars size ratio. Only Pluto’s satellite has a relatively larger size, but some people don’t even recognise Pluto as a real planet.

Secondly, this means that the general theory about satellites – that these were pieces of rocks captured by the planet – doesn’t hold for the Moon: it’s simply too big to have been captured by the Earth’s gravity.

Thirdly, the Moon rotates around itself in exactly the same amount of time as its revolution around the earth. This means that we can only see only one side of the Moon – hence the saying the far side of the Moon. Scientists are not sure why this is so – the dominant theory is that there is an assymmetry in its density. But this just raises the question why this should be so.

Could we resort to the anthropocentric principle? Maybe if the moon were not the way it is, the course of evolution would have been affected such that we wouldn’t have been here to ponder why the Moon is the way it is? But the anthropocentric principle always seemed like a fudge to me. Hmmm, more research is required.