A little night music

Mars and the moon are in conjunction tonight, as I happened to notice outside. With a full moon they are a spectacular show.

Sometimes it takes actually seeing celestial bodies sidling up to each other to remember that they are out there, pulling on the sun like buckets on the end of a rope. Except the moon -- it is pulling on us, sluicing the tides around the world. Now Mars is near opposition, and from here it will slide a bit farther west every night until it reaches the sunset. And all this because we are overtaking it, because we are swinging faster in our orbit around the sun.

I have a clear mental image of the full moon -- usually the full moon rising over the eastern horizon or low in the southeastern sky. In that position it seems the biggest, and you read all the time about why the illusion of a larger moon seems so real.

But it takes seeing the moon next to a planet, way overhead, to realize there's something wrong with the image. When you see the rising moon, you're looking at it sideways, with the north pole on the left. When you look at the moon right overhead, with your head in the north, it looks a bit unfamiliar, a bit strange. That's the way it's spinning, once every time it revolves around us.

And every time it goes around us, it goes a tiny bit slower, like a spinning figure skater letting her arms out. Because that's exactly what's happening; it's getting a bit farther away.

Mars is a bit further from us at this opposition than the last one, 26 months ago. Then, it was very near perihelion, and close to the sun means close to us as well. In fact, it was closer in 2003 then at any time in the last 59,000 years. NASA even commissioned an artist's conception of a Neandertal family watching it.

Of course, you know the Neandertals are stupid because they are looking away from the red orb in the sky.