Question

what is an light year why it is used​

Answer 1

Answer:

a light yeear is a unit to measure long distance that cannot be represented as kilometres

Answer 2

Answer:

$\huge{\bf{\underline{\red{Answer :}}}}$

$\huge{ \mathfrak{ \underline{light \: year}}}$

A light-year is a measurement of distance and not time (as the name might suggest). A light-year is the distance a beam of light travels in a single Earth year, or 6 trillion miles (9.7 trillion kilometers).

On the scale of the universe, measuring distances in miles or kilometers doesn't cut it. In the same way that you may measure the distance to the grocery store in the time it takes to drive there ("The grocery store is a 15-minute drive away"), astronomers measure the distances of stars in the time it takes for light to travel to us.