Answer:
A light-year is a unit of distance. It is the distance travelled by light in one year.
Step-by-step explanation:
A light-year is a unit of distance. It is the distance travelled by the light in one year. The speed of the light is 3×10⁸ m/s.
Light year also indicates how far back in time you are looking at. For example, if we are looking at something 10 light-years away that means it took light 10 years to reach us. So, in essence we are looking at the light which is 10 years old. In a way we are looking in the past.