Final answer:
The motion of the planets in the sky is a combination of their actual motions and Earth's motion around the Sun, creating complex paths. Retrograde motion, where a planet appears to move backwards, is a result of Earth's faster orbital speed overtaking the planet. Astronomers have been studying this phenomenon for a long time.
Step-by-step explanation:
The motion of the planets in the sky is a combination of their actual motions and the motion of Earth around the Sun. This creates complex paths for the planets as they appear to move in the sky over time. Sometimes, the planets will appear to move backwards, known as retrograde motion, due to Earth's faster orbital speed overtaking them. This phenomenon has fascinated astronomers for centuries.