Light year is a unit of:
Distance:
- A light year is a unit of distance used in astronomy to measure vast distances in space.
- It is defined as the distance that light travels in one year in a vacuum.
- Light travels at a speed of approximately 299,792 kilometers per second (or about 186,282 miles per second) in a vacuum.
- In one year, light can cover a distance of about 9.461 trillion kilometers (or about 5.879 trillion miles).
Explanation:
- The concept of a light year helps astronomers to express and understand the enormous distances between celestial objects.
- Since light travels at a finite speed, it takes time for light to travel from one point to another in space.
- The distance light travels in a year is a convenient unit to measure these large distances.
- For example, it takes about 8 minutes and 20 seconds for light from the Sun to reach Earth, so the distance between the Sun and Earth is about 8 light minutes.
- Similarly, the distance between stars, galaxies, and other astronomical objects can be expressed in light years to give a sense of their vastness.
- It is important to note that a light year is a measure of distance, not time. It represents how far light can travel in one year, rather than a specific duration of time.
Conclusion:
- The correct answer is B: distance.

Light year is the distance traveled by light in an year.