Question

question 6
1 pts
the apparent backward motion of a planet as seen against the background of stars is called __________ motion.
retrograde
prograde
doppler
parallax
proper

Explanation:

Retrograde motion is the apparent backward - motion of a planet with respect to the background stars. Prograde is the normal forward - motion. Doppler effect is about frequency changes due to relative motion. Parallax is related to the apparent shift in position of an object when viewed from different locations. Proper motion refers to the actual angular motion of a star across the celestial sphere.

Answer:

A. retrograde