Author Question: The occasional backward motion of the planets against the background of fixed stars is called _____. ... (Read 63 times)

kshipps · **on:** Jul 27, 2018

The occasional backward motion of the planets against the background of fixed stars is called _____.

A) anterograde motion
B) rotation
C) oscillation
D) retrograde motion

Question 2

Isaac Newton concluded that a force from Earth had to act on the Moon because:

A) some force is needed to pull the Moon away from Earth.
B) some force is needed to keep the Moon in a straight-line motion.
C) some force is needed to keep the Moon in motion in its orbit.
D) some force is needed to accelerate the Moon toward Earth.