Which of the following must be measured in order to determine a star's proper motion?
A) angular position at multiple times
B) mass
C) redshift or blueshift
D) radius

Question

Quizplus · Accepted Answer

Proper motion is the apparent motion of a star in the sky over time due to its actual motion through space. To determine this, the angular position of the star must be measured at multiple times and compared to determine its motion. Mass, radius, and redshift or blueshift are not directly related to a star's proper motion.

Which of the Following Must Be Measured in Order to Determine