Absolute magnitude is a measure of the intrinsic brightness of a celestial object, such as a star, galaxy, or asteroid, as it would appear if observed from a standard distance of 10 parsecs (about 32.6 light-years). Unlike apparent magnitude, which measures how bright an object appears from Earth, absolute magnitude eliminates the effect of distance, allowing astronomers to compare the true luminosities of objects. A lower absolute magnitude indicates a brighter object, while a higher number signifies a dimmer one. It provides a way to understand the actual energy output of stars and other celestial bodies.- Absolute magnitude (Wikipedia)
In astronomy, absolute magnitude (M) is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale. An object’s absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it were viewed from a distance of exactly 10 parsecs (32.6 light-years), without extinction (or dimming) of its light due to absorption by interstellar matter and cosmic dust. By hypothetically placing all objects at a standard reference distance from the observer, their luminosities can be directly compared among each other on a magnitude scale. For Solar System bodies that shine in reflected light, a different definition of absolute magnitude (H) is used, based on a standard reference distance of one astronomical unit.