The Zodiac and the Planets

The Zodiac ("Circle of Animals") is the name given to the band of the ecliptic encircling the earth. It is like a belt in space, about 15 degrees wide, across which the planets move and form their geometrical relationships. The Zodiac forms the stellar backdrop for the apparent path of the Sun, called the plane of the ecliptic. Astrologers divide the circle of the ecliptic into twelve parts, each subdivided into 30 degrees, making 360 degrees in all. The twelve divisions are called the Signs of the Zodiac. These signs are related (but not exactly identical) to the constellations (star groups) of the same name.
In astrology, the planets, sun, moon and other movable points (such as the moon's nodes) are still all described as "planets", the wanderers of the zodiac. From our point of view, the planets travel through the Zodiac in the course of their orbits around the Sun. Because they seem to be orbiting the Earth, the stars and planets rise in the east, move around the earth from east to west, then set in the west (due to the earth's rotation from west to east).
Astrologically, each sign symbolises certain specific characteristics in nature and, as the planets move through the signs, they stimulate (or perhaps simply reflect) reactions in both the individual and the collective here on Planet Earth. The Sun passes through one sign a month on its annual passage around the Zodiac.Other planets, because they actually orbit the Sun, seem to travel rather erratically through the Zodiac. This is really an illusion, generated by our changing earthly perspective with respect to the planets' placement in their orbits, but it does have some interesting effects. From time to time, all planets except the Sun and Moon slow to a halt ("station") and then begin to move backwards through the Zodiac. This phase is called retrograde motion, which has specific astrological consequences.