Astronomers must often know the distance to a star before they can fully understand its characteristics. Which of the following properties of a star typically requires a knowledge of distance before it can be determined?
A) its luminosity
B) its radial velocity
C) its temperature
D) its apparent brightness
E) all of the above

Question

Quizplus · Accepted Answer

Luminosity is a measure of a star's overall energy output, and it is dependent on both the star's temperature and size. However, in order to determine a star's luminosity, astronomers must first know its distance, as apparent brightness decreases with distance.

Astronomers Must Often Know the Distance to a Star Before