Polaris is a second magnitude star, and Phi Pegasi is about 16 times fainter than Polaris. What is the approximate magnitude of Phi Pegasi?
A) 18
B) (-14)
C) 3
D) (-3)
E) 5

Question

Quizplus · Accepted Answer

The magnitude scale is logarithmic, with a difference of 5 magnitudes corresponding to a factor of 100 in brightness. A star 16 times fainter than a second magnitude star would be approximately 3 magnitudes dimmer, making Phi Pegasi's magnitude about 5.

Polaris Is a Second Magnitude Star, and Phi Pegasi Is