Astrology is the occult science of gaining information about human affairs and terrestrial events by studying the movements and relative positions of celestial objects, especially stars, planets, and the moon. It is one of the most widely used forms of divination. Astrology, in its broadest sense, is the search for meaning in the sky.
Astrology has been dated to at least the 2nd millennium BCE, and has its roots in calendrical systems used to predict seasonal shifts and to interpret celestial cycles as signs of divine communications. Although not widely accepted by Egyptologists, some occultists believe astrology originated in ancient Egypt and was centered around the Egyptian decans and the Egyptian calendar.
Many cultures have attached importance to astronomical events, and some—such as the Hindus, Chinese, and the Maya—developed elaborate systems for predicting terrestrial events from celestial observations. Western astrology, one of the oldest astrological systems still in use, can trace its roots to 19th–17th century BCE Mesopotamia, from where it spread to Ancient Greece, Rome, the Arab world and eventually Central and Western Europe. Contemporary Western astrology is often associated with systems of horoscopes that purport to explain aspects of a person's personality and predict significant events in their lives based on the positions of celestial objects; the majority of professional astrologers rely on such systems.
Throughout most of its history, astrology was considered a scholarly tradition and was common in academic circles, often in close relation with astronomy, alchemy, meteorology, and medicine. It was present in political circles and is mentioned in various works of literature, from Dante Alighieri and Geoffrey Chaucer to William Shakespeare, Lope de Vega, and Calderón de la Barca. Following the end of the 19th century and the wide-scale adoption of the scientific method, researchers have successfully challenged astrology on both theoretical and experimental grounds, and have shown it to have no scientific validity or explanatory power. Astrology thus lost its academic and theoretical standing, and common belief in it has largely declined, until a resurgence starting in the 1960s.
Western astrology is a form of divination based on the construction of a horoscope for an exact moment, such as a person's birth. It uses the tropical zodiac, which is aligned to the equinoctial points.
Western astrology is founded on the movements and relative positions of celestial bodies such as the Sun, Moon and planets, which are analysed by their movement through signs of the zodiac (twelve spatial divisions of the ecliptic) and by their aspects (based on geometric angles) relative to one another. They are also considered by their placement in houses (twelve spatial divisions of the sky). Astrology's modern representation in western popular media is usually reduced to sun sign astrology, which considers only the zodiac sign of the Sun at an individual's date of birth, and represents only 1/12 of the total chart.
Along with Tarot divination, astrology is one of the core studies of Western esotericism, and as such has influenced systems of magical belief not only among Western esotericists and Hermeticists, but also belief systems such as Wicca that have borrowed from or been influenced by the Western esoteric tradition. Tanya Luhrmann has said that "all magicians know something about astrology," and refers to a table of correspondences in Starhawk's The Spiral Dance, organised by planet, as an example of the astrological lore studied by magicians.
Hindu natal astrology originated with Hellenistic astrology by the 3rd century BCE, though incorporating the Hindu lunar mansions. The names of the signs (e.g. Greek 'Krios' for Aries, Hindi 'Kriya'), the planets (e.g. Greek 'Helios' for Sun, astrological Hindi 'Heli'), and astrological terms (e.g. Greek 'apoklima' and 'sunaphe' for declination and planetary conjunction, Hindi 'apoklima' and 'sunapha' respectively) in Varaha Mihira's texts are considered conclusive evidence of a Greek origin for Hindu astrology.
The Indian techniques may also have been augmented with some of the Babylonian techniques.
Chinese and East Asian astrology
Chinese astrology has a close relation with Chinese philosophy (theory of the three harmonies: heaven, earth and man) and uses concepts such as yin and yang, the Five phases, the 10 Celestial stems, the 12 Earthly Branches, and shichen (時辰 a form of timekeeping used for religious purposes). The early use of Chinese astrology was mainly confined to political astrology, the observation of unusual phenomena, identification of portents and the selection of auspicious days for events and decisions.
The constellations of the Zodiac of western Asia and Europe were not used; instead the sky is divided into Three Enclosures (三垣 sān yuán), and Twenty-Eight Mansions (二十八宿 èrshíbā xiù) in twelve Ci (十二次). The Chinese zodiac of twelve animal signs is said to represent twelve different types of personality. It is based on cycles of years, lunar months, and two-hour periods of the day (the shichen). The zodiac traditionally begins with the sign of the Rat, and the cycle proceeds through 11 other animals signs: the Ox, Tiger, Rabbit, Dragon, Snake, Horse, Goat, Monkey, Rooster, Dog, and Pig. Complex systems of predicting fate and destiny based on one's birthday, birth season, and birth hours, such as ziping and Zi Wei Dou Shu (simplified Chinese: 紫微斗数; traditional Chinese: 紫微斗數; pinyin: zǐwēidǒushù) are still used regularly in modern-day Chinese astrology. They do not rely on direct observations of the stars.
The Korean zodiac is identical to the Chinese one. The Vietnamese zodiac is almost identical to Chinese zodiac except the second animal is the Water Buffalo instead of the Ox, and the fourth animal is the Cat instead of the Rabbit. The Japanese have since 1873 celebrated the beginning of the new year on 1 January as per the Gregorian calendar. The Thai zodiac begins, not at Chinese New Year, but either on the first day of fifth month in the Thai lunar calendar, or during the Songkran festival (now celebrated every 13–15 April), depending on the purpose of the use.
Criticism from the scientific community
The scientific community rejects astrology as having no explanatory power for describing the universe, and considers it a pseudoscience. Scientific testing of astrology has been conducted, and no evidence has been found to support any of the premises or purported effects outlined in astrological traditions. There is no proposed mechanism of action by which the positions and motions of stars and planets could affect people and events on Earth that does not contradict basic and well understood aspects of biology and physics.
Philosopher Thomas Kuhn argued that, though astrologers had, historically, made predictions that categorically failed, this in itself does not make astrology unscientific, nor do attempts by astrologers to explain away failures by claiming that creating a horoscope is very difficult. Rather, in Kuhn's eyes, astrology is not science because astrologers followed a sequence of rules and guidelines for a seemingly necessary field with known shortcomings, but they did no research because the fields are not amenable to research. While an astronomer could correct for failure, an astrologer could not. An astrologer could only explain away failure but could not revise the astrological hypothesis in a meaningful way.
As such, to Kuhn, even if the stars could influence the path of humans through life astrology is not scientific.
In the West, political leaders have sometimes consulted astrologers. For example, the British intelligence agency MI5 employed Louis de Wohl as an astrologer after claims surfaced that Adolf Hitler used astrology to time his actions. The War Office was "...interested to know what Hitler's own astrologers would be telling him from week to week." In fact, de Wohl's predictions were so inaccurate that he was soon labelled a "complete charlatan," and later evidence showed that Hitler considered astrology "complete nonsense."
After John Hinckley's attempted assassination of US President Ronald Reagan, first lady Nancy Reagan commissioned astrologer Joan Quigley to act as the secret White House astrologer. However, Quigley's role ended in 1988 when it became public through the memoirs of former chief of staff, Donald Regan.
In 2001, Indian scientists and politicians debated and critiqued a proposal to use state money to fund research into astrology, resulting in permission for Indian universities to offer courses in Vedic astrology. In February 2011, the Bombay High Court reaffirmed astrology's standing in India when it dismissed a case that challenged its status as a science.