Retrograde

A planet is Retrograde when, seen from Earth, it appears to move backwards through the zodiac. It is an optical effect caused by the difference in speed between Earth's orbit and the planet's, much as a train being overtaken by another seems to roll backwards. Astrology reads these periods as times of review, revision and turning inward on the matters the planet rules. The best known is Mercury retrograde, which happens three or four times a year and is associated with setbacks in communication, travel and technology.