Celestial Mechanics at the Coffee Machine

I read this week that Mercury has an orbital-rotational resonance of 3:2. As I understand it, that means that Mercury rotates twice on its own axis in exactly the same time that it takes to orbit the sun twice. I was quite comfortable with that statement until I read that Mercury is the only known body in the universe that has an orbital-rotational resonance other than 1:1, although most things apparently have no orbital-rotational resonance at all. That confused me. The only body in the universe of which I am aware that orbits a body once in the same period that it takes to rotate once on its own axis (1:1 orbital-rotational resonance), is the moon. I know this because we always see the same face of the moon you see. So, either I don't understand orbital-rotational resonance, or there are other bodies in the universe that do the same as the moon.

So, I did the only thing I could think of to doing resolve my dilemma, I asked my buddy Dr. Sweetenham at the coffee machine. Now the good doctor doesn't have an answer for everything of course, and he's really a mathematician, so he was slightly out of his comfort zone, but he likes an academic challenge, and he came back with an answer within minutes. It would seem that there are indeed many bodies in the known universe that rotate at the same frequency as their orbit, especially smallish bodies close to each other like the earth and the moon. So there you have it folks, a potted definition of orbital-rotational resonance if you ever get stuck for small-talk at the coffee machine.

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There was a plane crash at Heathrow yesterday, or a very rough landing, depending on your point of view. No one was seriously injured, but the plane suffered a reduction in the number of wheels and a loss of dimensional integrity. The dragon is due to fly out from Heathrow tomorrow. I toyed with the idea of trying to keep this information from her, but decided that it would probably best if she didn't find out about it by spotting the wreckage from her plane window. She's OK actually. She'll fly out tomorrow and I will join her in a couple of weeks. We will fly home together some time around valentines day, can't remember exactly. We've been married more than 3 years and we've never been apart for more than 1 night as far as I remember.

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In other news, Bobby Fisher is dead, the MOD have lost the bank details for 600,000 people, Stephen Fry has broken his arm, and British gas have raised prices by 15%.