About Retrograde Planets
What is retrograde motion of planets
If you look at the starry sky at night, you might notice that everything - stars, planets, the Moon - participate in perpetual movement. They rise in the East, culminate above our head and then set in the West. This movement is the result of our Earth's rotation around its axis, it is relatively fast: one full rotation of the sky takes 24 hours.
But there is also another kind of movement in the sky. If you make a photo of the sky at the same time, say 2:00 am, night by night, you will notice that the sky doesn't stay the same. The stars form a kind of fixed background, but the lights (well, you have a chance to see only the Moon at night) and planets move against the background of stars. This movement is much slower: the fastest of the travelers, the Moon, completes her path around the sky in about one month, while the slowest of those visible by naked eye, Saturn, does the same in about 30 years.
Planets are traveling along the ecliptic - the imaginable path of the Sun against the background of stars, hence the ecliptic is used as a kind of ruler or tape-measure that helps us to define where exactly a planet is located in the sky at the moment. If we say that Mercury is at the moment in the 2nd degree of Leo this simply means that, relative to the ecliptic, Mercury is somewhere between its imaginary points which could be labeled as "1° Leo" and "2° Leo".
Relative to the ecliptic, the planets are normally moving from West to East (opposite to that fast movement that results from the Eath's rotation around its axis). But at some stage in their movement a planet gradually slows down and then begins to move backwards, i.e. from East to West. This is exactly what is called retrograde motion. Its duration is different for different planets - for example, Mercury moves backwards for about 3 weeks, and then it resumes its normal forward movement, while Venus remains retrograde for about a month and a half.
There is nothing mystical in this change of direction. It is described in many textbooks on astronomy. This is a visual phenomenon, of course. No planet changes its direction in reality, they just continue to rotate around the Sun. There are schemes explaining how this phenomenon works but I don't want to make you bored by showing these schemes to you. If you are interested, you should be able to easily find them in astrological and astronomical textbooks.
Let me just propose you a simple analogy which can give you an idea of how it works. Say you are traveling in a train and there is another train moving next to yours in the same direction. If that another train is slightly slower than yours, it will seem to you that it goes backwards, while in fact it goes forward. The phenomenon of retrograde motion works in a similar way: depending on the relation between the speed of the Earth in the Space and the speed of another planet, it may seem that that planet goes backwards.
All these explanations were so far pure astronomy - a bit boring but necessary for understanding how things work. Now we are coming to astrology.