Apparent retrograde motion is an optical phenomenon observed in astronomy where a planet appears to move backward in its orbit, relative to the stars in the background, for a period of time. This effect is not due to any actual change in the direction of the planet's orbit but is instead caused by the relative positions and motions of the Earth and the other planet.
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A temporary reversal in a planet's apparent direction across the background sky, arising from the observer's changing position. For an outer planet observed from the Earth, the Earth overtakes it along its smaller, faster orbit. Different apparent reversals for two planets can produce three apparent conjunctions around one Sun-centred encounter, even when both follow prograde circular orbits.