# Pogson ratio

- the brightness ratio of two celestial objects that differ by one magnitude. On the Pogson scale a difference of 5 magnitudes is defined as a difference of 100 in the intensities of two stars; therefore a difference of 1 magnitude is equal to the fifth root of 100, i.e. 2.512

## Word Origin

C19: named after N. R. Pogson (1829–91), British astronomer

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