Question

what are light years used to measure? how fast light can travel in different mediums the time it would take to travel between objects in the universe distances between objects in the universe the brightness of stars in the night sky

Explanation:

A light year is defined as the distance that light travels in one Earth year. It is a unit specifically created to describe the vast spatial gaps between celestial objects in the universe, not speed, time, or stellar brightness.

Answer:

distances between objects in the universe