What did I miss? Why would we not be here without the moon?
If we didn't have an unusually large natural satellite to stabilize us, the Earth's orbital inclination would wobble drastically. IOW, our axis of rotation would wander all over the place, sometimes tilting by as much as 90 degrees, and back again, unpredictably. The climate, consequently, would be a chaotic mess. In the unlikely event that humans managed to evolve under such conditions, there'd be no chance that civilization could develop. So getting hit by that Mars-sized hunk of junk four-plus billion years ago is the best thing that ever happened to us, in a certain sense.
Thank you Bruce.
What about other planets that don't have one large moon, but rather a series of much smaller (relatively) moons. Do they wobble? Slightly, significantly? Maybe I'll go look it up later, but haven't the time now.
I do agree that we're lucky (blessed, fortunate, what-have-you) to be here at all.
There was an article in the paper a couple of days ago saying that some group of scientists somewhere had concluded that there are many more planets in our galaxy alone that are similar to earth than had been previously thought. Meaning, I suppose, that the likelihood of life elsewhere just went up. No comment about moons though.
I've heard that Mars does, and that one of the outer planets, Uranus or Neptune, I forget which, right now has it's axis pointing almost flat with the ecliptic, which means it's sort of rolling along it's orbit right now. But my limited knowledge ends there. (Though I will say we're also lucky to have a spinning nickel/iron core which generates a strong geo-magnetic field. This shields us from the bulk of the solar wind, without which said wind would have long ago eroded our atmosphere to almost nothing. Mars doesn't have this, and look what happened to its atmosphere.)