When observing planetary motions from Earth,the phrase "direct motion" refers to
A) the motion of the planet directly toward or away from Earth at certain parts of the planet's orbit.
B) a slow eastward motion of the planet from night to night against the background stars.
C) a slow westward motion of the planet from night to night against the background stars.
D) the apparent westward motion of the planet (along with the Sun,Moon,and stars)across the sky due to the rotation of Earth.

Question

Quizplus · Accepted Answer

Direct motion refers to the eastward or prograde motion of the planet from night to night against the background stars. This is the normal motion of planets as they orbit the sun in the same direction as Earth. It is opposite to retrograde motion, which is the apparent westward motion of a planet in its orbit as seen from Earth.

When Observing Planetary Motions from Earth,the Phrase "Direct Motion" Refers