There are times when the planets – but not the Sun or Moon – appear to be moving backwards in the sky. This is known as retrograde motion.
Mars and outwards are retrograde while in opposition to the Sun.
From Jupiter outwards they will turn retrograde just before they trine the Sun and go direct just after they complete the second trine. They have a retrograde period every year.
Mars makes the trine before it turns retrograde and turns direct before it makes the second trine, has one retrograde period every two years.
Venus and Mercury – have a different pattern. Because they can never be more than 48 degrees and 28 degrees, respectively, from the Sun, their retrograde periods occur then they as far away from the Sun as they can be.
Mercury has three retrograde periods a year of approximately three weeks and they will all begin in signs of the same element.
Venus has five retrograde period in eight years. Every eight years Venus is retrograde at the same point in the zodiac minus a few degrees. Over time, plotting these retrograde cycles draws out a heart in the sky.