Spectroscopy allows you to capture light from objects and dissect it. It is an extremely powerful tool in learning more about the universe around us. Spectroscopes come in many forms. At the simple level they allow us to see, through absorption lines the elements that make up a star. From this point we can also discover temperature. With more powerful spectroscopes we can confirm red shift and radial velocity and use light to calculate object movement, the rotational speed of planets and even discover exo-planets around distant stars.