General
Teach Astronomy is a great new online resource by Chris Impey (University of Arizona faculty) that includes a free textbook and a database of relevant images, videos and podcasts about astronomy.
Another free online astronomy textbook by Nick Strobel can be found here.
Wikibooks also has a decent free online General Astronomy textbook here
The Nebraska Astronomy Applet Project has a bunch of great simulators along with explanations and background information here. We’ll use some of these for in-class labs, but not all of them. If you’re struggling with a concept in the Celestial Motions, Exoplanets or Solar System units, this is a good first place to start looking.
If you bought the “etext” with Mastering Astronomy, it is also a great place to look for more information about any particular topic.
The Astronomical Society of the Pacific has a great website with free podcasts on a variety of subjects from famous astronomers.
NASA has a great public website with details on all current and future space missions, as well as tons of information about the planets in our solar system.
Observing
The program Stellarium is great (and free!) planetarium software. It is useful for exploring motions in the sky and figuring out how to find objects in the sky at any given time. It is available free for download here.
Monthly sky maps listing significant transient celestial events (planet motions, meteor showers, comets etc.) for the month and where to find them are located here and are updated around the first of every month.
see the Extra Credit Options page for links to places around town to do extra credit.