Last modified on 9th August 2000.
Encyclopædia Galactica
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Magnitude (mag or m)
A measurement of the brightness of a star or other celestial
object. On the magnitude scale, the lowest numbers refer to
objects of greatest brightness. A difference in magnitude of
5 corresponds to a brightness ratio of 100:1. Therefore, if
two stars differ by one magnitude their brightnesses differ
by a factor equal to the fifth root of 100, that is, 2.512.
The brightness of stars as observed from the Earth (their
apparent magnitude) depends on their intrinsic magnitude,
their distance from us, and the
extinction in between. The absolute magnitude is a measure
of intrinsic luminosity on the magnitude scale, defined as the
apparent magnitude an object would have at the distance of ten
parsecs.
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Created by
Rami T. F. Rekola