Proper motion is the motion
A) of a star or other object across (at right angles to) the line of sight.
B) of a star or other object along the line of sight, toward or away from us.
C) allowed by the laws of physics.
D) of a star or other object in any direction through space.

Question

Quizplus · Accepted Answer

Proper motion refers to the apparent motion of a star or celestial object across the sky, perpendicular to our line of sight, as observed from Earth. It does not include motion toward or away from us, which is measured by radial velocity.

Proper Motion Is the Motion