Magnitude (astronomy)

In astronomy, magnitude refers to the brightness of stars. The magnitude scale is a logarithmic scale, with increasing brightness represented as lower numbers. The apparent magnitude of a star, planet, nebula, or other astronomical object is based on the brightness of the object as seen from earth (or, more properly, from the viewpoint of the observer). The absolute magnitude of an object is based on the brightness of the object to an observer 10 parsecs distant.

The original magnitude scale was a sorting of stars into "first magnitude" through "sixth magnitude". The scale has since developed to be continuous and open-ended, and logarithmic.

Apparent and absolute magnitudes of some well-known objects: