Traditions

Zodiac signs, 16th century European woodcutThere are many traditions of astrology, some of which share similar features due to the transmission of astrological doctrines between cultures. Other traditions developed in isolation and hold completely different doctrines, although they too share some similar features due to the fact that they are drawing on similar astronomical sources.


Current traditions
The main traditions used by modern astrologers are:

Indian astrology
Western astrology
Chinese astrology

Indian and Western astrology share a common ancestry as horoscopic systems of astrology and are essentially similar in content. Both traditions focus on the casting of an astrological chart or horoscope, a representation of celestial entities, for an event based on the position of the Sun, Moon, and planets at the moment of the event. The main difference between the two traditions is that Indian astrology uses the sidereal zodiac, linking the signs of the zodiac to their original constellations, while Western astrology uses the tropical zodiac. Because of the precession of the equinoxes, over the centuries the twelve zodiacal signs in Western astrology no longer correspond to the same part of the sky as their original constellations. In effect, in Western astrology the link between sign and constellation has been broken, whereas in Indian astrology it remains of paramount importance.

In Chinese astrology a quite different tradition has evolved. By contrast to Western and Indian astrology, the twelve signs of the zodiac do not divide the sky, but rather the celestial equator. The Chinese evolved a system where each sign corresponds to one of twelve 'double-hours' that govern the day, and to one of the twelve months. Each sign of the zodiac governs a different year, and combines with a system based on the five elements of Chinese cosmology to give a 60 (12 x 5) year cycle. The term Chinese astrology is used here for convenience, but it must be recognised that versions of the same tradition exist in Japan, Vietnam, Thailand and other Asian countries.

In modern times, these traditions have come into greater contact with each other, notably with Indian and Chinese astrology having spread to the West, while awareness of Western astrology is still fairly limited in Asia. Astrology in the Western world has diversified greatly in modern times. New movements have appeared, which have jettisoned much of traditional astrology to concentrate on different approaches, such as a greater emphasis on midpoints, or a more psychological approach. Some recent Western developments include:

Modern tropical and sidereal horoscopic astrology
Cosmobiology
Psychological astrology
Sun sign astrology
Hamburg School of Astrology
Uranian astrology, subset of the Hamburg School

Historical traditions
Throughout its long history, astrology has come to prominence in many regions and undergone developments and change. There are many astrological traditions that are historically important, but which have largely fallen out of use today. Astrologers still retain an interest in them and regard them as an important resource. Historically significant traditions of astrology include:

Arab and Persian astrology (Medieval, near Eastern)
Babylonian astrology (Ancient, near East)
Egyptian astrology
Hellenistic astrology (Classical antiquity)


Esoteric traditions

Extract and symbol key from 17th century alchemy text.Further information: Renaissance magic
Many mystic or esoteric traditions have links to astrology. In some cases, like Kabbalah, this involves participants incorporating elements of astrology into their own traditions. In other cases, like divinatory tarot, many astrologers themselves have incorporated the tradition into their own practice of astrology. Esoteric traditions include, but are not limited to:

Alchemy
Chiromancy
Kabbalistic astrology
Medical astrology
Numerology
Rosicrucian or "Rose Cross"
Tarot divination

Historically, alchemy in the Western World was particularly allied and intertwined with traditional Babylonian-Greek style astrology; in numerous ways they were built to complement each other in the search for occult or hidden knowledge. Astrology has used the concept of the four classical elements of alchemy from antiquity up until the present day. Traditionally, each of the seven planets in the solar system known to the ancients was associated with, held dominion over, and "ruled" a certain metal.

The zodiac


The zodiac is the belt or band of constellations through which the Sun, Moon, and planets transit across the sky. Astrologers noted these constellations and so attached a particular significance to them. Over time they developed the system of twelve signs of the zodiac, based on twelve of the constellations they considered to be particularly important. The Western and Indian zodiac signs have a common origin in the tradition of horoscopic astrology, and so are very similar in meaning. In China on the other hand, the development of the zodiac was different. Although the Chinese too have a system of twelve signs (named after animals), the Chinese zodiac refers to a pure calendrical cycle, as there are no equivalent constellations linked to it like the Western or Indian zodiacs. The common choice of twelve zodiac signs is understandable considering the interaction of the Sun and Moon was central to all forms of astrology. Twelve cycles of the Moon — the months — coincided with one solar year, making twelve a natural choice.

The majority of Western astrologers base their work on the tropical zodiac which divides the sky into twelve equal segments of 30 degrees each, beginning with the first point of Aries, the point where the line of the earth's celestial equator and the ecliptic (the Sun's path through the sky) meet at the northern hemisphere spring equinox. Due to the precession of the equinoxes, the slow changing of the way Earth rotates in space, the zodiacal signs in this system bear no relation to the constellations of the same name but stay aligned to the months and seasons.

Practitioners of the Indian astrological tradition and a minority of Western astrologers use the sidereal zodiac. This zodiac uses the same evenly divided ecliptic but approximately stays aligned to the positions of the observable constellations with the same name as the zodiacal signs. The sidereal zodiac differs from the tropical zodiac by an offset called the ayanamsa which steadily increases as the equinoxes drift further.

Horoscopic astrology

Horoscopic astrology is a system that was developed in the Mediterranean region and specifically Hellenistic Egypt around the late 2nd or early 1st century BCE. The tradition deals with two-dimensional diagrams of the heavens, or horoscopes, created for specific moments in time. The diagram is then used to interpret the inherent meaning underlying the alignment of celestial bodies at that moment based on a specific set of rules and guidelines. A horoscope was calculated normally for the moment of an individual's birth, or at the beginning of an enterprise or event, because the alignments of the heavens at that moment were thought to determine the nature of the subject in question. One of the defining characteristics of this form of astrology that makes it distinct from other traditions is the computation of the degree of the Eastern horizon rising against the backdrop of the ecliptic at the specific moment under examination, otherwise known as the ascendant. Horoscopic astrology has been the most influential and widespread form of astrology across the world, especially in Africa, India, Europe, and the Middle East, and there are several major traditions of horoscopic astrology whose origins are Hellenistic, including Indian, Medieval, and most other modern Western traditions of astrology.


The horoscope


Central to horoscopic astrology and its branches is the calculation of the horoscope or astrological chart. This two-dimensional diagrammatic representation shows the celestial bodies' apparent positions in the heavens from the vantage of a location on Earth at a given time and place. The horoscope is also divided into twelve different celestial houses which govern different areas of life. Calculations performed in casting a horoscope involve arithmetic and simple geometry which serve to locate the apparent position of heavenly bodies on desired dates and times based on astronomical tables. In ancient Hellenistic astrology the ascendant demarcated the first celestial house of a horoscope. The word for the ascendant in Greek was horoskopos from which horoscope derives. In modern times, the word has come to refer to the astrological chart as a whole.

Origins
The origins of much of the astrological doctrine and method that would later develop in Asia, Europe, and the Middle East are found among the ancient Babylonians and their system of celestial omens that began to be compiled around the middle of the 2nd millennium BCE. This system of celestial omens later spread either directly or indirectly through the Babylonians to other areas such as India, China, and Greece where it merged with pre-existing indigenous forms of astrology.[citation needed]. This Babylonian astrology came to Greece initially as early as the middle of the 4th century BCE, and then around the late 2nd or early 1st century BCE after the Alexandrian conquests, this Babylonian astrology was mixed with the Egyptian tradition of decanic astrology to create horoscopic astrology. This new form of astrology, which appears to have originated in Alexandrian Egypt, quickly spread across the ancient world into Europe, the Middle East and India.

Before the scientific revolution
From the classical period through the scientific revolution, astrological training played a critical role in advancing astronomical, mathematical, medical and psychological knowledge. Astrological influences included the observation and long-term tracking of celestial objects. It was astrologers who provided the first systematic documentation of the movements of the Sun, the Moon, the planets, and the stars. The differentiation between astronomy and astrology varied from place to place; they were indistinguishable in ancient Babylonia and for most of the Middle Ages, but separated to a greater degree in ancient Greece. Astrology was not always uncritically accepted before the modern era; it was often challenged by Hellenistic skeptics, church authorities, and medieval thinkers.

The pattern of astronomical knowledge gained from astrological endeavours has been historically repeated across numerous cultures, from ancient India through the classical Maya civilization to medieval Europe. Given this historical contribution, astrology has been called a protoscience along with pseudosciences such as alchemy.

Many prominent scientists, such as Nicholas Copernicus, Galileo Galilei, Tycho Brahe, Johannes Kepler, Carl Jung and others, practiced or significantly contributed to astrology