Chapter 12, Problem 1CQ

What is a light-year, and how is it defined?

To determine

The significance of light year and its definition.

Answer to Problem 1CQ

A light-year is a unit of length used to measure the astronomical distances. It is defined as the distance travelled by the light in $1$ year. One light year is equal to $9.5\times {10}^{12}\text{km}$.

Explanation of Solution

In astronomy, there were no referent points of comparison so that standard units were created for the measurement of distances. A light-year is a unit of length which is used to describe the astronomical distances.

Therefore, a light year is the distance travelled by the light in $1$ year. One light year is equal to $9.5\times {10}^{12}\text{km}$.