# physics

ly = light years

Stars P and Q have the same luminosity, but P is 30 ly from Earth and Q is 40 ly from Earth. What is the ratio of their brightness as viewed from Earth?

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1. their brightness ratio is the ratio of the inverse of the square of their distances

bP / bQ = (dQ / dP)^2

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2. So it would be 900:1600
= 9:16?

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