The Greek astronomer Hipparchus established a numerical scale to describe the brightness of each star appearing in the sky. The brightest stars in the sky were assigned an apparent magnitude , and the dimmest stars visible to the naked eye are assigned . The difference between them corresponds to a factor of 100 in brightness. For objects within the immediate neighborhood of the Sun, the absolute magnitude and apparent magnitude from any distance (in parsecs, with 1 pc = 3.2616 light-years) are related by