As a rule, retrograde planets presage a period of seemingly inevitable or fated events, which relate to their sphere of influence.
They present us with a series of events over which we seem to have little or no control, relating especially to the sign in which the retrogradation occurs.
For example, Uranus retrograde in Pisces presents quite different sets of circumstances from those generated when it retrogrades into Aquarius.
A retrograde period is best seen as a cycle, which begins when the planet begins to slow to a halt before travelling backwards through the zodiac and ends when the planet returns to the point where it first paused. However, during the cycle, the planet's energy is most powerful (and more likely to generate critical events of universal importance) when the planet makes a station, appearing motionless in the sky. These stationary periods occur at the beginning of the cycle (when the planet first halts as it prepares to move backwards) and midway through the cycle when the retrograde planet slows to a stop before moving forward again.
Current Retrograde Movements
Mercury usually turns retro three times a year, but there are four retrograde periods this year. Click here for more.