Which of the following best describes a $\text{light year}$ as used in astronomy?

• A. The time it takes for the $\text{Earth}$ to orbit the $\text{Sun}$.
• B. The distance that $\text{light}$ travels in one $\text{year}$.
• C. The time it takes for $\text{light}$ to travel around the $\text{Earth}$ once.
• D. The distance from the $\text{Earth}$ to the $\text{Sun}$.

Answer: (B)

Verified step by step guidance

1. Understand that a light year is a unit of distance, not time.
2. Recall that light travels at a constant speed in a vacuum, approximately \$3 \times 10^{8}$ meters per second.
3. Recognize that one year is a measure of time, specifically the time it takes for the Earth to complete one orbit around the Sun, about 365.25 days.
4. Combine these concepts: a light year is the distance light travels in the span of one year.
5. Therefore, the best description of a light year is the distance that light travels in one year.