Question

which statement accurately describes a light - year?
it is the shape of a galaxy.
it is the distance that light travels in a year.
it is a yearly measurement of light given off by stars.
it is the amount of time it takes light to travel one million kilometers.

Explanation:

A light - year is a unit of distance. Light travels at a very high speed (\(c = 3\times10^{8}\space m/s\)). In one year (\(t=365\times24\times3600\space s\)), the distance \(d = c\times t\) that light travels is defined as a light - year.
The first option is wrong because a light - year has nothing to do with the shape of a galaxy. The third option is incorrect as it is not a measurement of the amount of light given off by stars. The fourth option is wrong because it is a distance, not a time for a specific distance (one million kilometers is much less than a light - year).

Answer:

It is the distance that light travels in a year.