Question

Light year is a unit of:

• A. time
• B. speed
• C. distance
• D. none of these

Answer 1

Answer: (C)

distance

Answer 2

Light year is a unit of distance. More specifically, it is theunit of lengthused to measure the distance between astronomical objects.

According to a definition by International Astronomical Union (IAU), one light year is the distance that light can travel in one year in a vacuum. Light moves at a velocity of $3\times {{10}^{8}}\,m/s$ . Thus, one light year is almost equivalent to 9.46 trillion kilometers (9.46 × 1012 Km). Light year is often used to measure the distance of stars.

The most commonly used unit to measure distance in astronomy is parsec. 1 parsec is approximately 3.26 light years.