The `Origins' theme of NASA research asks the question of how life originated here, and how it might have originated elsewhere. There's a wealth of information there. The Astrobiology Roadmap spells out how NASA aims to understandd the possibilities of extraterrestrial life. The NASA `PlanetQuest' website contains detailed information and current news on the search for planets, and especially Earth-like planets. `Astrobiology Magazine' is a great web-based news site on Astrobiology. Another similar site is `Astrobiology.com' which is aimed more at working scientists. The SETI (Search for ExtraTerrestrial Intelligence) Institute has been at this a long time. The Exploratorium in SF has a nice `Origins' page. Thinkquest has an Astrobiology webpage that contains some good introductory information. Life In The Universe is another good overview page put up by the European Space Agency. The debate on whether there is evidence for past life on Mars is described in some course materials at Dartmouth. Another good web source for information about the search for life in the solar system in general is available here. For general astronomy, The Astronomy Picture of the Day is always a good place to go for stunning pictures and nice explanations. Light Years, and great explanations for some other Astronomy jargon, is described at the Electronic Sky. For descriptions of really bad Astronomy in the movies or on TV, the Bad Astronomy website is indespensible. The University of Arizona has a really good set of pages for introductory biology information. The Cosmic Distance Scale is well discussed by a web page at NASA by Maggie Masetti. Journey through the Galaxy contains a lot of good information about our solar system, other solar systems, stars, and exploration. The BBC has several nice web pages about stars including about their spectra (week 3) and their birth, life, and death (week 4). A NASA page covers some of the same material --- spectra and burning in stars. Berkeley has a good introduction to Extremophiles. NASA has a Lunar Exploration Timeline which is quite complete. I'll continue to add more links here as the course continues.