Binary Star

Here is an imaginary landscape of a planet in orbit around a binary star. At least a third of all the stars you see in the night sky are actually binary, or double stars. Some are even triples, or quadruples, or more. Hundreds of these multiple stars can be seen as such in small telescopes. Many pairs show differences in brightness and color caused by the differing masses and temperatures of the companions. A pair of stars as close together as those in my image could not be resolved in a telescope. It would be detected spectroscopically, with the spectra showing two sets of absorption lines. Visual binaries are typically separated by billions of miles.

Image copyright by Joe Bergeron.