Stargazers to Starships

I rediscovered a great astronomy and spaceflight educational site I had bookmarked a while ago. "Stargazers to Starships" is the work of David P. Stern, and although its web design is simple (no Flash or Javascript here), the content is great. It's logically organized and the explanations are clear and well written. Most pages also have "questions from users" section at the end (with links to answers), which is a wonderful feature. Dr. Stern also provides lesson plans based on his site, with problems for students as well as suggested questions for discussion.

The main sections are "Astronomy of Earth's Motion in Space" (including a recently added section on the solar system), "Newtonian Mechanics" (with a great optional section on spaceflight to Mars), "The Sun and Related Physics," and "Spaceflight and Spacecraft." There's even a math refresher section and a timeline.

This is a great resource for teachers or informal educators as well as for student projects.