Which of the following would be the most appropriate unit of measurement to measure the distance between galaxies?

A. light-seconds
Incorrect. Galaxies are extremely far apart so light-seconds would not be an appropriate unit of measurement to measure the distance between galaxies.

B. light-minutes
Incorrect. Galaxies are extremely far apart so light-minutes would not be an appropriate unit of measurement to measure the distance between galaxies.

C. light-hours
Incorrect. Galaxies are extremely far apart so light-hours would not be an appropriate unit of measurement to measure the distance between galaxies.

D. light-years
Correct! Galaxies are extremely far apart so the distance between galaxies is measured in light years.

Light travels at a distance of 1,080,000,000 km/hour. Uranus is 2,909,606,000 km from the sun. How many light hours is Uranus from the sun?

A. .037 light years
Incorrect. Check your calculation.

B. 12,105,832,320,000,000 light years
Incorrect. Check your calculation.

C. 2.7 light years
Correct!

D. 669,600,000 light years
Incorrect. Check your calculation.

Betelgeuse is the eighth brightest star and is classified as a red super giant. Betelgeuse is approximately 640 light years away from Earth. How long would it take light from Betelgeuse to reach Earth?

A. 640 hours
Incorrect. If the distance was measured in light years this would be the correct answer.

B. 64.0 years
Incorrect. Check the placement of the decimal.

C. 640 years
Correct!

D. .640 years
Incorrect. Check the placement of the decimal.

You are on an imaginary planet that is 473 trillion kilometers away from Earth. You are looking through a very high-powered telescope, and you witness a child’s tenth birthday party. How old is that child on Earth at the time you are watching the child’s tenth birthday party?

A. 50 years old
Incorrect. Remember you are seeing the child’s 10th birthday.

B. 400 years old
Incorrect. Check you calculation.

C. 60 years old
Correct!

D. 10 years old
Incorrect. Check you calculation.