Saw comet Holmes last night.
I don't know if I've mentioned it, but we get pretty good stars around our house. First, we're high up -- it's not the Andes, but our house is about 1200 meters (4,000 feet) above sea level. Second, while downtown Yerevan can get pretty smoggy, there's not a lot of pollution in our neighborhood. And third, there aren't a lot of bright lights around. So on a clear night, we can step into the back yard and see stars and more stars.
Lately the nights have been clear. Gorgeous fall weather, cool and dry. I walk outside after putting Jacob to bed and the Pleiades are just rising, a delicate bit of lacework against the purple sky. Orion comes up over the neighbor's house just around bedtime, Mars blazing orange in Gemini. It's nice.
The comet: it's not anything spectacular. Not a blazing thing streaking across the sky. The comet looks like a tiny little smudge. It's "third magnitude", which means about as bright as a medium-bright star: bright enough that you could see it in a city or town, but just barely. You have to stare a moment to see that it's a smudge instead of a star.
On the other hand, it's pretty cool. Comet Holmes is a short-period comet, orbiting the Sun between Mars and Jupiter. Most of the time it minds its own business, making an orbit every seven years and never getting bright enough to see. But a couple of weeks ago it suddenly got around a million times brighter, and became visible to the naked eye.
Why? Nobody knows. One possibility is that it hit something. But comet Holmes seems to have brightened like this once before -- when it was first discovered, back in the 1890s. So maybe there's something funny about the comet's internal structure. We don't know. But this doesn't seem to be the normal sort of cometary display, which happens when comets get too close to the sun and start to evaporate. This is something different. But we don't know just what.
Anyway, the comet is now about 150 million miles away and moving outwards on its orbit. It will probably get dimmer over the next few weeks and then disappear. If you know your constellations, it appears as an extra "head" on top of Perseus. If you don't, just go out in late evening -- between ten and midnight, say; it's directly overhead around midnight -- and scan the upper part of the sky for a medium-bright star that looks a little funny. I took Claudia outside and she spotted it instantly. (Of course, Claudia is good at spotting things. Very different from me; I can fail to notice large objects immediately in front of me. And often do. But that's a story for another post.)
It's not a big deal, but it does remind me of one thing I really like about our house. I'll be sorry when the weather gets too cold (soon!) to hang out in the back yard seeing stars.