Question

The picture below shows the position of Earth and two stars.

Star 2 is 52 light years from Earth and 18 light years from Star 1. If Star 1 explodes as a supernova, in how many years would the explosion be seen from Earth?

18

34

52

70

Answer 1

34 light years because star 1's distance from earth is equal to star 2's distance from earth minus 18. 

Answer 2

34

Explanation:

Given that:

• Star 2 is 52 light years from Earth

• Star 2 is 18 light years from Star 1

distance from Earth to Star 2 = distance from Earth to Star 1 + distance from Star 1 to Star 2

distance from Earth to Star 1 = distance from Earth to Star 2 - distance from Star 1 to Star 2

distance from Earth to Star 1 = 52 - 18 = 34 light years