Astrology is a range of divinatory practices, recognized as pseudoscientific since the 18th century, that propose that information about human affairs and terrestrial events may be discerned by studying the apparent positions of celestial objects. Different cultures have employed forms of astrology since at least the 2nd millennium BCE, these practices having originated in calendrical systems used to predict seasonal shifts and to interpret celestial cycles as signs of divine communications. Most, if not all, cultures have attached importance to what they observed in the sky, 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 Islamic 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.
The history of astronomy focuses on the contributions civilizations have made to further their understanding of the universe beyond earth's atmosphere. Astronomy is one of the oldest natural sciences, achieving a high level of success in the second half of the first millennium. Astronomy has origins in the religious, mythological, cosmological, calendrical, and astrological beliefs and practices of prehistory. Early astronomical records date back to the Babylonians around 1000 BCE. There is also astronomical evidence of interest from early Chinese, Central American and North European cultures.
The zodiac is a belt-shaped region of the sky that extends approximately 8° north and south celestial latitude of the ecliptic – the apparent path of the Sun across the celestial sphere over the course of the year. Within this zodiac belt appear the Moon and the brightest planets, along their orbital planes. The zodiac is divided along the ecliptic into 12 equal parts, called "signs", each occupying 30° of celestial longitude. These signs roughly correspond to the astronomical constellations with the following modern names: Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, and Pisces.
Western astrology is the system of astrology most popular in Western countries. It is historically based on Ptolemy's Tetrabiblos, which in turn was a continuation of Hellenistic and ultimately Babylonian traditions.
Hindu astrology, also called Indian astrology, jyotisha and, more recently, Vedic astrology, is the traditional Hindu system of astrology. It is one of the six auxiliary disciplines in Hinduism that is connected with the study of the Vedas.
In Western astrology, astrological signs are the twelve 30-degree sectors that make up Earth's 360-degree orbit around the Sun. The signs enumerate from the first day of spring, known as the First Point of Aries, which is the vernal equinox. The astrological signs are Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, and Pisces. The Western zodiac originated in Babylonian astrology, and was later influenced by the Hellenistic culture. Each sign was named after a constellation the sun annually moved through while crossing the sky. This observation is emphasized in the simplified and popular sun sign astrology. Over the centuries, Western astrology's zodiacal divisions have shifted out of alignment with the constellations they were named after by axial precession of the Earth while Hindu astrology measurements correct for this shifting. Astrology was developed in Chinese and Tibetan cultures as well but these astrologies are not based upon the zodiac but deal with the whole sky.
The Celtic calendar is a compilation of pre-Christian Celtic systems of timekeeping, including the Gaulish Coligny calendar, used by Celtic countries to define the beginning and length of the day, the week, the month, the seasons, quarter days, and festivals.
Astrological belief in relation between celestial observations and terrestrial events have influenced various aspects of human history, including world-views, language and many elements of culture. It has been argued that astrology began as a study as soon as human beings made conscious attempts to measure, record, and predict seasonal changes by reference to astronomical cycles.
Astrology and astronomy were archaically treated together, but gradually distinguished through the Late Middle Ages into the Age of Reason. Developments in 17th century philosophy resulted in astrology and astronomy operating as independent pursuits by the 18th century.
In many languages, the names given to the seven days of the week are derived from the names of the classical planets in Hellenistic astronomy, which were in turn named after contemporary deities, a system introduced by the Sumerians and later adopted by the Babylonians from whom the Roman Empire adopted the system during late antiquity. In some other languages, the days are named after corresponding deities of the regional culture, beginning either with Sunday or with Monday. The seven-day week was adopted in early Christianity from the Hebrew calendar, and gradually replaced the Roman internundinum.
Ancient Celtic religion, commonly known as Celtic paganism, was the religion of the ancient Celtic peoples of Europe. Because there are no extant native records of their beliefs, evidence about their religion is gleaned from archaeology, Greco-Roman accounts, and literature from the early Christian period. Celtic paganism was one of a larger group of polytheistic Indo-European religions of Iron Age Europe.
Indian astronomy refers to astronomy practiced in the Indian subcontinent. It has a long history stretching from pre-historic to modern times. Some of the earliest roots of Indian astronomy can be dated to the period of Indus Valley civilisation or earlier. Astronomy later developed as a discipline of Vedanga, or one of the "auxiliary disciplines" associated with the study of the Vedas dating 1500 BCE or older. The oldest known text is the Vedanga Jyotisha, dated to 1400–1200 BCE.
Babylonian astronomy was the study or recording of celestial objects during the early history of Mesopotamia. The numeral system used, sexagesimal, was based on sixty, as opposed to ten in the modern decimal system. This system simplified the calculating and recording of unusually great and small numbers.
Often called lunar mansion, a lunar station or lunar house is a segment of the ecliptic through which the Moon passes in its orbit around the Earth. The concept was used by several ancient cultures as part of their calendrical system.
Babylonian astrology was the first known organized system of astrology, arising in the second millennium BC.
Historically, astrological and astronomical symbols have overlapped. Frequently used symbols include signs of the zodiac and classical planets. These originate from medieval Byzantine codices. Their current form is a product of the European Renaissance. Other symbols for astrological aspects are used in various astrological traditions.
Egyptian astronomy started in prehistoric times, in the Predynastic Period. In the 5th millennium BCE, the stone circles at Nabta Playa may have made use of astronomical alignments. By the time the historical Dynastic Period began in the 3rd millennium BCE, the 365 day period of the Egyptian calendar was already in use, and the observation of stars was important in determining the annual flooding of the Nile.
Budha is the Sanskrit word for the planet Mercury, personified as a god.
In astrology, planets have a meaning different from the astronomical understanding of what a planet is. Before the age of telescopes, the night sky was thought to consist of two similar components: fixed stars, which remained motionless in relation to each other, and moving objects/"wandering stars", which moved relative to the fixed stars over the course of the year(s).
