If a supernova was first seen in 1572 C.E. and its distance from Earth is measured to be 2 kpc, approximately when did the supernova actually explode?
A) 1572 B.C.E.
B) 4968 B.C.E.
C) 428 B.C.E.
D) 4968 C.E.

Question

Quizplus · Accepted Answer

The light from the supernova took approximately 2,000 years to reach Earth (1 kiloparsec (kpc) equals about 3,262 light-years, so 2 kpc is roughly 6,524 light-years, but for simplicity and given the context of the question, we're approximating to 2,000 years). Therefore, if it was first seen in 1572 C.E., it actually exploded around 2000 years before that, which would be around 428 years before the start of the Common Era (C.E.), making 4968 B.C.E. the correct approximation.

If a Supernova Was First Seen in 1572 C