What is retrograde motion? via Shareaholic
What is retrograde motion? For the planets | Space | EarthSky
What is retrograde? Sometimes the planets appear to change direction in the sky. This retrograde motion is entirely an illusion caused by the Earth passing the slower moving outer planets.
Illustration of retrograde motion
What is retrograde motion and why does a planet like Mars appear to change directions in the night sky? Is it playfully looping about in its orbit around the sun or is something less strange going on?
Animation of Mars in retrograde
Retrograde motion of Jupiter or Mars or Saturn in our sky is an illusion, caused by Earth's passing these slower-moving outer worlds. But there's a real retrograde motion, too.
The dazzling “star” near the waxing moon on January 1, 2 and 3, 2017 is Venus. Mars is also along a line between the sunset location on your horizon and the moon and Venus in your sky.
Geocentricity explains retrograde motion of Mars