The main tools used by astronomers are telescopes, spectrographs, spacecrafts, cameras, and computers. Astronomers use many different types of telescopes to observe objects in the Universe. Some are located right here on earth and some are sent into space. Just about everything we know about the Universe comes from the study of the light emitted by objects in space. Astronomers use these tools (especially telescopes) very often. Astronomers also use a lot of physics and mathematics in their work.