stellar brightness It is the light energy from that star in 1 second per 1 unit of area brightness is a unit quantity. But the brightness rating has no unit. It's just a given number. with the principle that there is no unit It's just a given number. The principle is that the stars are the faintest that the naked eye can see. It has a brightness rating of 6 and the brightest stars have a brightness rating of 1 star with different brightness ratings. 1 will have about 2.5 times the difference in brightness.
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