About half of the points of light that we see when we look up into the night sky are not single stars. The point of light that we see with our eyes is actually the combined light from two or more stars that are relatively close to each other.
Most stars live in multiple star systems where two or more stars are orbiting each other.
Our Sun is a single star. This lab will focus on binary stars - two stars that are orbiting around each other. Binary star systems are important to astronomers because they can tell us the masses of the individual stars, as well as some other stellar properties. Binary stars can appear to us in many different forms. The different types explained below are called visual , astrometric , eclipsing , and spectroscopic .