Question

A red supergiant is observed in a globular cluster in another galaxy (located 150,000 light years away). It is predicted, based on its mass and age of the star that it will become supernova in about 10,000 years. When will this supernova be visible on Earth? a) 10,000 years from now. b) 10,000 years ago. c) 150,000 years ago. d) 150,000 years from now. e) 160,000 years from now.

Answer 1

Answer:

e) 160,000 years from now.

Explanation:

The distance of the supergiant from us is

d = 150,000 light years

This means that the light emitted by the star takes 150,000 years to reach us.

We are told that the star will become a supergiant in

t = 10,000 years

from now. When this will happen, the light from the supernova will not reach us instantaneously, but it will take 150,000 years to travel the distance between us and the star.

Therefore, the supernova will be visible on Earth only after:

T = 10,000 y + 150,000 y = 160,000 years

So, option E) is correct.