The signs of the Zodiac were created by dividing theeclipticinto twelve equal parts. The ecliptic is the orbit of the sun over the year. The part of astronomy, which deals with the signs of the Zodiac, is called Zodiac, which means "circle of creatures". Unlike in astronomy, in Western astrology the Zodiac simply corresponds to the ecliptic. It has been divided into 12 sections, each 30° in size. The starting point here is the beginning of spring. Thus, it also corresponds to the basis of the Zodiac. This classification is called the tropical astrology (tropoi = turn).
The sidereal astrology
The division of the signs of Zodiac based on the visible constellations is called sidereal astrology. In a reform of the Egyptian calendar in the third century BC, the months were first named after the signs of the Zodiac. The first sign in this calendar was Cancer, not Aries. This was later determined as such. The Cancer was also used later as the first sign, since during its time the summer solstice takes place.
Since the positions of the signs of the Zodiac have slightly changed during the last millennia while the vernal equinox kept being the same, they no longer coincide with the constellations of the same name. The Zodiac is the basis for the horoscope, each sign is subordinate to a segment. The location of the sun at the time of birth determines the sign of the Zodiac. Since the sun is slowly but constantly changing, an exact division into the zodiacal signs is not possible, yet it is given use in the common calendar days.
The horoscopes are based on the lunar calendar, whose origins date back to the Middle Ages. The concept of the signs of the Zodiac is even older: It goes back to the ancient Egyptian period, in the third millennium BC. As a horoscope-like system, the zodiacal signs have been used since the second millennium BC. The ancient Greeks also adopted this system. Approximately 500 BC, the character traits associated with the constellations were described for the first time. If something extraordinary happened to the time of a particular constellation, it was assumed that this would be repeated in the future with the same constellation.