The number of stars which one can see without telescope is about 6,000. Before the invention of telescope, only six magnitudes or degrees of brightness of the stars were recognized. Today with the help of telescope stars up to 21st magnitude can be seen. There are 22 stars of the first magnitude. The brightness of all stars is Sirius, having magnitude of -1.6. Thus Sirius is 1,000 times brighter than the faintest star which can be seen with the naked eye.