The APPARENT MAGNITUDE which a star would have if it were located at a standard distance from the Earth of 10 PARSECS, i.e. 32.6 light years. Clearly the apparent magnitude of a star depends upon the amount of light it emits (see also LUMINOSITY) and on its distance (brightness diminishes as the square of distance); if all stars were at the same distance then their apparent magnitudes would be true indicators of their relative luminosities. By definition, the absolute magnitude of stars provide a measure of their relative luminosities, by comparing the apparent brightnesses which stars would have if they all lay at the same distance.
