Stars A and B have identical luminosities,but star A is nine times brighter than star B.If star A is 9 parsecs from Earth,how far away is star B?
A) 1 parsec
B) 3 parsecs
C) 27 parsecs
D) 81 parsecs

Question

Quizplus · Accepted Answer

The brightness of a star as seen from Earth is inversely proportional to the square of its distance. If star A is nine times brighter than star B, it means star B is at a distance that is the square root of 9 times further away than star A, which is 3 times further. Since star A is 9 parsecs away, star B must be 9 * 3 = 27 parsecs away.

Stars a and B Have Identical Luminosities,but Star a Is