Retrograde motion of a planet is its apparent backward motion through the sky, as observed from Earth. This apparent retrograde motion is caused by the Earth traveling past a slower-moving outer planet (Jupiter, Saturn, Uranus, Neptune and also Pluto, even if from 2006 Pluto is considered a dwarf planet) or when the Earth is itself passed by a faster-moving inner planet (Mercury, Venus or Mars).
So, this is like the apparent motion of the slower car on the highway – an optical illusion. But it is important, from our perspective: we live on Earth and we judge things from an earthly perspective.
Some astrologers consider this apparent backward movement of the planets was to be unlucky, because it goes against the natural order of movement – the direct movement. But a retrograde planet is not necessarily something bad – actually, it is a chance to recognize, understand and correct past mistakes.
Retrograde Planets in 2017
Mercury retrograde in Capricorn and Sagittarius: December 19th,2016 – January 8th, 2017
Mercury retrograde in Taurus and Aries: April 9th – May, 3rd
Mercury retrograde in Virgo and Leo: August, 12th – September, 6th
Mercury retrograde in Sagittarius: December, 3rd – December 22nd
Venus retrograde in Aries and Pisces: March 4th – April 15th
Jupiter retrograde in Libra: February, 6th – June, 9th
Saturn retrograde in Sagittarius: April 5th – August, 25th
Uranus retrograde in Aries: August 2nd, 2017 – January, 2nd, 2018
Neptune retrograde in Pisces: June, 16th – November, 22nd
Pluto retrograde in Capricorn: April, 20th – September, 28th