This site offers a range of free multiple-choice quizzes to test your knowledge of astronomy and the universe.
Each quiz includes 15 questions on the chosen subject area, and you can go through that set of questions as many times as you like until you're getting them all right, or take new quizzes on the same subject.
The main quiz sections are :
History - Quizzes on the the history of space exploration, and the development of our understanding of the universe
Observing - Test your knowlege of the constellations and other astral phenomema, plus the techniques of astronomical observation
The Universe - Quizzes on the Solar System, cosmology and even extreme astrophysics!