Astrology (from Greek: αστρολογ?α = ?στρον + λ?γος) refers to several systems of observing, interpreting and organizing knowledge about the envireonment and human existence, based on the relative positions and movement of various celestial bodies. The main ones are the Sun, Moon, planets, and lunar nodes as seen at the time and place of a birth or other event being studied.

It is believed that the influence of the planets and stars on earthly affairs allows them to both predict and affect the destinies of individuals, groups, and nations. Though often regarded as a science throughout its history, astrology is widely considered today to be diametrically opposed to the findings and theories of modern Western science.

Central to all astrology is the natal chart (also called the horoscope, natus, or birth chart). This is a visual picture of the planetary and other positions as if it were seen by someone standing in the time and place and actually looking up into the sky. The chart also contains the positions below the horizon – what an observer could not see. Interpretation of a natal chart is governed by:

1. the relative positions of the heavenly bodies to each other,
2. their positions relative to the Fixed Stars,
3. their position relative to the horizon.

Common forms of astrology include Western astrology, Chinese astrology, Jyotish (Vedic astrology) and Kabbalistic astrology. All of these can be subdivided by type, such as natal (the study of a person’s birth chart), horary (a chart drawn to answer a specific question), and electional astrology (a chart drawn ahead of time to determine the best moment to begin an enterprise or undertaking). The majority of Western astrologers based their work on the tropical zodiac, but some Western and all Jyotish (Hindu) astrologers use the sidereal zodiac.

Origins

All peoples in all cultures practiced some form of heavenly observations and linked them to earthly occurances. Native Americans, ancient Greeks, Druids, MesoAmericans (just to name a few) all pursued the study of celestial omens. What differentiates this from our definition of astrology is the use (or non-use) of a chart. In its origins, modern astrology was just a linking of celestial movement with mundane events.

According to Rob Hand (Project Hindsight), astrology, as we know it, came into being only once in time and in one place. That place is Mesopotamia (roughly modern Iraq).

In the beginning, Mesopotamian astrology was only an examination of the heavens for omens. The most extensive omen lore was the Enuma Anu Enlil. Assembled sometime in the second millennium B.C.E., these included weather phenomena as well as astronomical ones.

When the Mesopotamians began to see patterns in the celestial movements which then correlated with patterns in human events, Astrology made its next leap. The Venus Tables of Ammizaduga (date unknown) are systematic observations of the phases of Venus plus their omen significations, those significations being based on past observations. The general belief is that these tables date from the reign of Ammizaduga about 146 years after Hammurabi.

More than that, they saw the heavenly movements as indicators of Divine Will in the Here and Now. This is the probable motive of the studies that led to astrology.

Over centuries of observations, the Mesopotamians,and especially the Babylonians**, could now accurately estimate the positions of the planets at any time in the future. Ptolemy records, and modern science confirms, that accurate and systematic eclipse records were kept from 747 B.C.E. onward into the Hellenistic period after the conquests of Alexander the Great.

Early Mesopotamian recordings indicate no zodiac, but noted sidereal observations such as:

19 from the Moon to the Pleiades;
17 from the Pleiades to Orion;
14 from Orion to Sirius. . .

Note: a zodiac requires a fixed number of regular divisions such as the twelve signs of the modern zodiacs, the twenty-seven lunar mansions of the Hindu lunar zodiac, and so on.

Three Stages of Astrology

Van der Waerden theorizes that astrology went through three phases. The first phase would be the oral and recorded omens. The second phase would include a zodiac in the modern sense, twelve 30 degree signs. There is no personal horoscopy in this middle level, but great attention is paid to the transits of Jupiter through the signs at the rate of approximately one sign per year. From this is clearly descended the Chinese practice of assigning each year to a zodiacal sign, and probably also the system of annual profections in later horoscopic astrology. There were no astrological houses at this point. Van der Waerden dates this middle phase as being from about 630 to 450 B.C.E., AKA the Pre-Hellenistic period (800 – 400 B.C.E.).

Several birthcharts have been found written in cuneiform. The oldest has been dated by A. Sachs to April 29, 410 B.C. Here is the translation as given by Fagan.

Month (?) Nisan (?) night (?) of (?) the (?) 14th (?). . .
son of Shuma-usur, son of Shumaiddina, descendant of Deke was born.
At that time the Moon was below the "Horn" of the Scorpion
Jupiter in Pisces, Venus
in Taurus, Saturn in Cancer.
Mars in Gemini, Mercury which had set (for the last time) was
(still) in (visible).
. . . etc., etc.

With only sign positions and no delineations, this is an early example. Later cuneiform charts did not add too much more, but the positions were far more precise. 

Out of Egypt and Back to Greece

Pharaonic Egypt had a great interest in astronomy, but they were more concerned with the Fixed Stars rather than planets. The Egyptians were masters of aligning buildings, temples and especially the pyramids to fixed stars. The best known example is the three pyramids of Giza aligned to Orion’s belt.

The Mesopotamians inherited the sexagesimal system of numbers from the Sumerians. This enabled the Mesopotamians to do complex computations. The Egyptians had nothing like it. But they did have a strong sense of a need for terrestrial matters to be brought into harmony with the heavens.

By Aristotle’s time, ca. 350 B.C.E.,  the beginnings of natal astrology came to be. Since he was Alexander the Great’s tutor, his ideas were spread as far as Alexander’s conquests went, and those were both Persia and Egypt in 332 BCE. The Persians became excellent astrologers and preserved the wisdom during some of the Dark Ages.

The pre-Hellenistic Babylonian astrologers may have used a rising degree (Ascendant), but we just do not know for sure.  Valens’ teachings refer to an even earlier textbook… perhaps somewhere between 300 – 200 B.C.E. Another "mystical" figure from this same period is one called Hermes Trismegistus. His writings are widely repeated among a large percent of the earliest Greek astrologers, but we have nothing from this time period.

In summary, we have the most rudimentary of natal astrology in the 5th century B.C.E. and by ca. 100 B.C.E., we have a very complete natal astrology.

** Babylonia (Babylonian Bâbili,"gate of God"; Old Persian Babirush),Was the ancient country of Mesopotamia, known originally as Sumer and later as Sumer and Akkad, lying between the Tigris and Euphrates rivers, south of modern Baghdâd, Iraq.

Astrology Timeline

c.1300-1236 B.C.E. Ramses II fixes the CARDINAL points, Aries, Libra,Cancer and Capricorn

c.668 B.C.E. Earliest surviving horoscope

572-490 B.C.E. Pythagoras theory:what embodies greater wisdom=numbers, what embodies great beauty=harmony. The source of planetary aspects as we know today.

428-348 B.C.E. Plato’s Timeus identifies the universe as a living entity created by therein,composed of four elements which distinguish form another by molecular form, although all four elements are interconnected and interrelated in a perfect harmonious form.

490-420 B.C.E. Empedocles replaces theory of matter with theory of all substances derive form the four elements: fire,air,water and earth. Basic principle of developing astrological interpretations.

460-377 B.C.E. Hippocrates uses astrological principles by the studying the human body in relation to rhythms which astronomers had observed within the universe as a whole.

384-322 B.C.E Aristotle’s Elementary properties of matter:
FIRE= Warm, dry
EARTH= Cold, dry
AIR=Moist,warm
WATER=Moist,cold

c.330 B.C.E. Berossus (Chaldean Astrologer that Alexander the Great returned to the west with) found School of Astrology at the Island of Cos. Greek Astrologers taught there.

63 B.C.E-14 C.E. Augustus has coins stamped with his sign, Capricorn

Birth of Christ announced by the Magi, astrologers following a star.

c.120-180 C.E. Claudius Ptolemy, author of Tetrabiblios, the greatest astrological textbook

204-270 C.E. Plotonius, founder of Neoplatonism, accepts validity of astrology, but insists on free will.

354-430 C.E. St. Augustine. He accepts Astrology when young but then turned violently against it. The arguments he advanced are still used by churchmen today.

c.400 C.E. The great library of Alexandria is dispersed with the loss of many Astrological texts.

410-485 C.E. Proclus, philosopher and successor to Plato, writes paraphrase of Ptolemy’s Tetrabiblios.

c.450 C.E. Gaius Julius Solinus writes long interpretation of the horoscope of Rome

c.550 C.E. Horapollon publishes Hieroglyphics, describing how the sacred beetle lives in strict conformity with astrological theory

700-800 C.E. Arab scientists and astrologers keep alive Classical learning.

10th Century, Ibn Yunis, Moslem astronomer, compiles at Cairo the Hakamite tables of planetary motions.

940-1020 C.E. Firdausi, or Abul-Qasim Mansur,Persia’s epic poet, writes the Sah-Namah of over 60,000 couplets , containing many astrological references.

1125 C.E. University of Bologna founds Chair of Astrology

1125-1274 C.E. St. Thomas Aquinas accepts idea of Astrology as applied to natural phenomena: ‘the celestial bodies work indirectly on the condition of understanding.’

c1214-1294 C.E. Roger Bacon, a distinguished Franciscan philosopher, praises the new art of mathematics as essential for the proper practice of astrology.

1225-1230 C.E. Cambridge University founded. Astrology taught there from 1250.

c1254-1324 C.E. Marco Polo, Venetian explorer, estimates that 5000 astrologers work in China (Kanbalu) alone.

c1280 C.E. Johannes Campanus, mathematician and chaplain to Pope Urban IV, devises a new method of House division.

1468-1549 C.E. The Popes that supported Astrology thrived during this time: Sixtus IV, Julius II, Leo X, and Paul the III.

1527-1608 C.E John Dee, astrological advisor to Queen Elizabeth the I, and practiced alchemy and espionage for the Queen.

1546-1601 C.E. Tyro Brahe, court astronomer and astrologer, says anyone who denies astrology is ignoring the ‘clear evidence’. He then proved the physical effect of the planets on the Earth.

1571-1630 C.E. Johannes Kepler, holds that Astrology ‘derives from experience which can be denied only by people who have not examined it.’

1602-1681 C.E. William Lilly, the best known astrologer of his day, simultaneously patronized by the Roundheads and the Cavaliers.

1603-1668 C.E. Placidus, a monk and a Paduan professor, originates the still popular House system for division of the celestial sky.