Absolute Magnitude

Recall the definition of absolute magnitude

Absolute magnitude is a useful way of finding out how bright a star would appear from a certain point in space. By doing this we understand each star's true magnitude.

The true absolute magnitude for the Sun is 4.2 whereas to us on Earth it is -27.

It is the brightness of a star at a distance of 10 parsecs which is 32.6 light years.

It is calculated using the following equation:

M = m + 5 - 5 log D

M = Absolute Magnitude
m= apparent magnitude


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Curious about Astronomy? How do astronomers measure the brightness of stars?


You can practice some apparent magnitude calculations on the Magnitude Calculations page.