Comet

Looking down the tubes of our refractor (and its finder scopes), out the slit, past the Moon, at a fuzzball three times as distant as Mars.

No, I haven't abandoned the blog. It's just been a busy, erm ... month.

Anyhow, Comet 17P/Holmes is putting on a show at the moment, what with getting a half-million times brighter in a matter of hours. Now it's about 48 hours later, and sky watchers everywhere are having a ball with it.

Obviously I can't let everybody else have all the fun, and I just so happen to have a century-old 10-inch refractor up on the roof and some history with astrophotography, so here's my contribution. (Click pictures for full-rez versions.)

We estimated the comet was at about magnitude 2.5 at the time, which generally agrees with the reports coming in, and looked to be about an arcminute across. Given that it's about 1.5 AU from us (three times as far away as Mars!) that coma is around 60,000 kilometers wide. If it's around 30 hours post-eruption in the picture below, that dust cloud is expanding at 600 meters per second. Reports indicate that it's expanded considerably tonight.

Conspicuously, there's no tail. For one thing, it'll take some time for the sun to sculpt this expanding cloud; for another, the tail would be pointed almost directly away from us, anyway. It's actually on its way out now, but it only has to get out to the orbit of Jupiter, so 17P isn't going anywhere in a hurry. Whether or not it stays bright, on the other hand, is anyone's guess.

A closer look at the sky, and then a much closer look through the 10-inch.