* Mercury’s retrograde motion * This video explains Mercury’s apparent retrograde motion in our skies: the inner planet appears to retrace its steps a few times per year. Every planet does this, every year. Retrograde motion is an optical illusion caused by differences in the planets’ orbital speeds. When a planet seems to reverse its direction in the sky, it’s called retrograde motion (from the Latin word retrogradus – "going backward"). Courtesy: Star Walk Based on video by James O'Donoghue /

2.6M views · 48K reactions | Jupiter and Saturn go retrograde 敖 This...

Jupiter, the largest planet in our solar system, undergoes an apparent retrograde motion as seen from Earth. But what does that mean? Retrograde motion is an optical illusion that occurs when a planet appears to move backward in the sky due to differences in orbital speeds. As Earth, moving faster in its inner orbit, overtakes Jupiter, the gas giant seems to temporarily reverse direction before continuing its normal prograde motion. Jupiter’s next retrograde motion will take place from November