magnitude

Greatness of rank or position.

Greatness in size or extent.

Greatness in significance or influence.

The brightness of a celestial body on a numerical scale for which brighter objects have smaller values. Differences in magnitude are based on a logarithmic scale that matches the response of the human eye to differences in brightness so that a decrease of one magnitude represents an increase in apparent brightness by a factor of 2.512.

A unit on such a scale of brightness.