Planets usually move across our night sky from west to east relative to the background stars. This steady motion is a result of their orbits around the Sun. But every so often, a planet like Mars appears to hit the brakes, reverse direction, and move backward - a puzzling motion known as retrograde. This animation breaks down the mystery behind retrograde motion, focusing specifically on Mars. You'll see how the motion of Earth and Mars in their respective orbits creates the illusion of Mars loo

Why Mars Moves Backward - This is the retrograde motion of Mars. So why does Mars sometimes appear to move backward in the night sky? Retrograde motion is an optical illusion that happens when Earth, moving faster in its orbit, overtakes Mars. As we pass it, Mars appears to slow down, stop, and move westward temporarily — even though it's still moving forward in space. Because Mars orbits farther from the Sun than Earth does, it takes longer to complete one orbit. When Earth "laps" Mars about ev

Mercury's Retrograde Motion refers to an optical illusion that occurs when the planet appears to move backward in the sky, relative to the stars, due to the relative positions and speeds of Earth and Mercury. Mercury orbits the Sun faster than Earth, so as Earth overtakes Mercury in its orbit, it creates the illusion of Mercury reversing direction. This happens several times a year, but because Mercury is close to the Sun, it's often difficult to observe from Earth. The planet is typically too c