Stars are interesting and complicated objects which can not be directly understood since probes can not endure the 4000+ K temperatures at their surfaces. There are billions of them around us in various stages of evolution. Our Sun is a pretty average star which is right in the middle of its main sequence lifetime. Other types of stars include red giants, red super giants, and white dwarfs. To learn more, simply click on the area of the diagram below that interests you.

Stars are classified by their characteristic spectra, and their luminosity class. The path along which a star progresses during its lifetime is largely determined by its mass.