Taking over the world

I was watching Independence Day the other day and something occurred to me - the aliens who want to take over the planet always fly down to Earth and take us on, and we have tanks and nukes and shit, which inevitably destroy the advancing alien hordes. Oh, and Tom Jones works too.

The thing is, surely it would make more sense for the aliens to destroy the moon. It's undefended for a start, and would be fairly simple for an advanced alien race to destroy.

Once the moon was destroyed, all the aliens would need to do would be to sit back and watch us get destroyed by floods and hurricanes and things, and then when we're all dead pop down in their spaceship with a flag and they've got themselves a planet.

It would make a shit film though, obviously.