A supernova that occurred 30,000 years ago in a galaxy 100,000 light-years away will beobserved on Earth:
A)30,000 years from now.
B)70,000 years ago.
C)70,000 years from now.
D)100,000 years ago.
E)100,000 years from now.

Question

Quizplus · Accepted Answer

Since the supernova occurred 30,000 years ago in a galaxy 100,000 light-years away, the light from the explosion has been traveling through space towards Earth for 30,000 years. Therefore, the light will reach Earth 70,000 years from now, making choice C the correct answer. The supernova occurred 30,000 years ago, and since it is in a galaxy 100,000 light-years away, the light from the supernova will take 100,000 years to reach Earth. Therefore, the supernova will be observed on Earth 70,000 years from now.

A Supernova That Occurred 30,000 Years Ago in a Galaxy