Astronomy Practice Exam

Disable ads (and more) with a membership for a one time $2.99 payment

Prepare for the Astronomy Exam with detailed questions and explanations. Enhance your understanding with quizzes and study guides. Start your preparation today!

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

Practice this question and more.

Which of the following best describes what a light year measures?

Time
Light intensity
Distance
Mass

The correct answer is: Distance

A light year is a unit of measurement that describes the distance that light travels in a vacuum in one year. Since light moves at an incredible speed of approximately 299,792 kilometers per second (about 186,282 miles per second), the distance covered over the course of a year adds up to roughly 9.46 trillion kilometers or about 5.88 trillion miles. This measurement is particularly useful in astronomy for expressing vast distances between stars and galaxies, making it easier for scientists and astronomers to communicate distances in the universe. Thus, when one refers to a light year, they are specifically measuring how far light can travel in one year, reinforcing that it relates solely to distance rather than time, light intensity, or mass.