A couple of years ago, some astronomers hit upon the idea of taking publicly available telescope data and building an online community around it for the purpose of cataloging galaxies. While the aim of the project is serious, it can provide a lot of fun for its users. And that's the key to its appeal for me. Most of the people who participate in Galaxy Zoo are complete amateurs with little or no training in astronomy but like a well written game, Galaxy Zoo guides them, helping them recognize the patterns that classify different types of galaxies. This allows Galaxy Zoo's thousands of users to catalog hundreds of thousands of galaxies. The project has already led to some major discoveries and has now moved into a second stage which makes it even more addictive. Before, Galaxy Zoo would allow users to choose between two major galaxy shapes, spiral and elliptical or label them a star or unknown object. Now it has become more interactive, prompting the user to provide more information about the pattern of the galaxy's appearance. It's fun for the user and provide the website with a lot data in a short time. It also allows users to undo mistakes—a feature which was sorely missing from the old Galaxy Zoo. Finally, it allows users to save their favorite galaxy pictures and share them with other users in the site's bustling forums. Part game and part social network, Galaxy Zoo provides an exciting look at science in action.