A liquid mirror telescope is made by spinning a reflective fluid, such as mercury, at a constant rate. This rotation produces a parabolic surface, which is an ideal shape for a telescope mirror. (You can try this yourself.) While these mirrors can be built to be large and orders of magnitude cheaper than solid mirrors, they have the disadvantage that they can only look straight up. Creating mirrors this way is not new; they have a history [.ps] that dates back to Newton. However, they have recently regained attention as the technology behind proposals to build an enormous (20m+) telescope on the moon. (A less technical treatment here.)
posted by Upton O'Good on Jul 1, 2008 - 36 comments

Mark VandeWettering makes telescopes, and has written a set of guides for those who would like to build their own. Francis O'Reilly has made a similar set of guides, except as a series of videos.
posted by Upton O'Good on Jun 4, 2008 - 13 comments

HobbySpace hosts an exhaustive collection of information and links about space-related hobbies, including amateur astronomy, satellite design, and rocketry for both beginners and experts.
posted by Upton O'Good on Dec 2, 2007 - 3 comments