ASTRO-110 Lecture Notes - Lecture 30: Inverse-Square Law, N. R. Pogson, Automobilclub Von Deutschland
18 Sep 2020
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Document Summary
Just about the simplest astronomical observation you can make is also one of the most profound. When you look at the stars in the night sky they are not all of the same brightness. (also if you look carefully on a moonless night you will see that they are not all the same colour. ) The greek astronomer hipparchus (c. 190 bc c. 120 ad) proposed the first scale of stellar brightness. He classified the visible stars into 6 categories, the brightest being 1 and the faintest 6. If you think about it, from the modern point of view, this scale is backwards. We would like larger numbers to represent brighter stars not fainter ones. But that"s the way it is and we are stuck with it. The scale remained unchanged until sir william herschel (1738-1822) and norman. We now talk about the apparent visual magnitude (mv) of a star.
