Make observations of variable stars and help discover new ones. Variable stars are stars that change brightness over time for any number of different reasons. By studying variable stars, we can learn more about the specific star and other stars like it, such as their mass, composition and evolution. Through the American Association of Variable Star Observers (AAVSO), participants can either make their own observations of stars, analyze existing star data, or create open source software tools for studying variable stars.
(image by NASA, ESA, and H. Bond (STScI))