Question

How is light year helpful when describing the size of a galaxy? Provide an example.

Answer 1

Answer: Astronomers can also establish how far back in time they are observing by measuring in light-years. Everything we see in the night sky has already happened since light takes time to reach our eyes.

Example: Interstellar and intergalactic distances are measured in light-years.

Answer 2

Answer: It is helpfull because it shows how long it takes to get to one place.

Explanation: Like for an example when you go on a vacation and you want to see how long it takes to get there. And that is what they use in space.