Galaxy Zoo 2

In celebration of the 100 Hours of Astronomy event, Galaxy Zoo aims to get one million galaxies classified before the hundred hours are up. At this writing, it looks like they'll easily meet that goal (well done, everyone!), but you can still try your hand at it any time you want. Who knows? You might even find your very own "voorwerp".

The new classification is more fun than the old, which was not bad to begin with. There are more questions, the interface is nicer, you can go back and review the galaxies you've classified and mark images as favorites. You can invert the image you're looking at, which both looks cool and can help you see features you might otherwise miss. If the galaxy you're looking at has a bar or spiral arms, you get to play "Galaxy Wars" (kinda cheesy name, but what the hey) to gauge whether the features are more or less prominent compared to some other galaxy.

If you think of a sequence from indistinct blob to disk with a blob in the middle to full-featured galaxy, you can imagine the galaxies actually form over stupefyingly long periods of time -- which is more or less the point of the whole exercise. [Actually, no. It turns out that Hubble was quite clear that his now-famous sequence of galaxy forms was meant as a taxonomic device and makes no claim about the forms through which galaxies evolve. Current theory holds that elliptical galaxies form via mergers of spiral galaxies.].

Oddly fascinating fun. Recommended.