Suppose that an astronomer discovers an active galaxy, and that the intensity of the radiation from the galactic nucleus fluctuates in intervals of 8 minutes. Based on her observations, the astronomer should infer that the active nucleus of this galaxy is about ___ in diameter. (Hint: It takes light about 8 minutes to reach Earth from the Sun.)
A) 1 AU
B) 1 Mpc
C) 8 AU
D) 8 light-years

Question

Quizplus · Accepted Answer

The fluctuations in radiation intensity suggest that the source is about the size of the distance light can travel in 8 minutes, which is approximately 1 Astronomical Unit (AU), the average distance from the Earth to the Sun.

Suppose That an Astronomer Discovers an Active Galaxy, and That