Zodiac

These signs roughly correspond to the astronomical constellations with the following modern names:[2][3] Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, and Pisces.

The English word zodiac derives from zōdiacus,[5] the Latinized form of the Ancient Greek zōdiakòs kýklos (ζῳδιακός κύκλος),[6] meaning "cycle or circle of little animals".

[9] Although the zodiac remains the basis of the ecliptic coordinate system in use in astronomy besides the equatorial one,[10][11] the term and the names of the twelve signs are today mostly associated with horoscopic astrology.

[12] The term "zodiac" may also refer to the region of the celestial sphere encompassing the paths of the planets corresponding to the band of about 8 arc degrees above and below the ecliptic.

[15][16] Around the end of the fifth century BC, Babylonian astronomers divided the ecliptic into 12 equal "signs", by analogy to 12 schematic months of 30 days each.

[20] Because the divisions were made into equal arcs of 30° each, they constituted an ideal system of reference for making predictions about a planet's longitude.

[23] Knowledge of the Babylonian zodiac is said to be reflected in the Hebrew Bible; E. W. Bullinger interpreted the creatures that appear in the book of Ezekiel (1:10) as the middle signs of the four quarters of the zodiac,[25][26][better source needed] with the Lion as Leo, the Bull as Taurus, the Man as Aquarius and the Eagle as a higher aspect of Scorpio.

Martin and others have argued that the arrangement of the tribes around the Tabernacle (reported in the Book of Numbers) corresponded to the order of the zodiac, with Judah, Reuben, Ephraim, and Dan representing the middle signs of Leo, Aquarius, Taurus, and Scorpio, respectively.

Such connections were taken up by Thomas Mann, who in his novel Joseph and His Brothers, attributes characteristics of a sign of the zodiac to each tribe, in his rendition of the Blessing of Jacob.

[citation needed] The Babylonian star catalogs entered Greek astronomy in the 4th century BC, via Eudoxus of Cnidus.

[15] Babylonia or Chaldea in the Hellenistic world came to be so identified with astrology that "Chaldean wisdom" became among Greeks and Romans the synonym of divination through the planets and stars.

The earliest extant Greek text using the Babylonian division of the zodiac into 12 signs of 30 equal degrees each is the Anaphoricus of Hypsicles of Alexandria (fl. 190 BC).

[30] Under the Greeks, and Ptolemy in particular, the planets, Houses, and signs of the zodiac were rationalized and their function set down in a way that has changed little to the present day.

The tropical zodiac (of Mesopotamian origin) is divided by the intersections of the ecliptic and equator, which shifts in relation to the backdrop of fixed stars at a rate of 1° every 72 years, creating the phenomenon known as precession of the equinoxes.

[37] During the Abbasid era, Greek reference books were translated into Arabic, and Islamic astronomers then did their own observations, correcting Ptolemy's Almagest.

[39]: 66  Whilst horoscopes were generally widely accepted by society, many scholars condemned the use of astrology and divination, linking it to occult influences.

[42] Many theologians and scholars thought that it went against the tenets of Islam; as only God should be able to determine events rather than astrologers looking at the positions of the planets.

The "Longitude of the Sun" columns show the sign (represented as a digit from 0 to and including 11), degrees from 0 to 29, minutes, and seconds.

[45] Mughal king Jahangir issued an attractive series of coins in gold and silver depicting the twelve signs of the zodiac.

[46] What follows is a list of the signs of the modern zodiac (with the ecliptic longitudes of their first points), where 0° Aries is understood as the vernal equinox, with their Latin, Greek, Sanskrit, and Babylonian names.

[52][53] The following table compares the Gregorian dates on which the Sun enters a sign in the Ptolemaic tropical zodiac, and a sign in two sidereal systems: one proposed by Cyril Fagan, and a fourteen-sign system proposed by Steven Schmidt which adds Ophiuchus (see below) and Cetus (the IAU boundaries of which just graze by the ecliptic): The beginning of Aries is defined as the moment of vernal equinox, and all other dates shift accordingly.

In addition, because the Earth's axis is at an angle, some signs take longer to rise than others, and the farther away from the equator the observer is situated, the greater the difference.

Hydra in the Early Bronze Age marked the celestial equator and was associated with Leo, which is shown standing on the serpent on the Dendera zodiac.

This results in the originally unified zodiacal coordinate system drifting apart gradually, with a clockwise (westward) precession of 1.4 degrees per century.

Ptolemy quotes from Hipparchus' now-lost work entitled "On the Displacement of the Solstitial and Equinoctial Points" in the seventh book of his 2nd century astronomical text, Almagest, where he describes the phenomenon of precession and estimates its value.

[71] This is known as the "tropical zodiac" (from the Greek word trópos, turn)[72] because its starting point revolves through the circle of background constellations over time.

Ptolemy demonstrates that the principle of the tropical zodiac was well known to his predecessors within his astrological text, the Tetrabiblos, where he explains why it would be an error to associate the regularly spaced signs of the seasonally aligned zodiac with the irregular boundaries of the visible constellations: The beginnings of the signs, and likewise those of the terms, are to be taken from the equinoctial and tropical points.

This rule is not only clearly stated by writers on the subject, but is especially evident by the demonstration constantly afforded, that their natures, influences and familiarities have no other origin than from the tropics and equinoxes, as has been already plainly shown.

And, if other beginnings were allowed, it would either be necessary to exclude the natures of the signs from the theory of prognostication, or impossible to avoid error in then retaining and making use of them; as the regularity of their spaces and distances, upon which their influence depends, would then be invaded and broken in upon.

[34]Astronomically, the zodiac defines a belt of space extending 8°[74] or 9° in celestial latitude to the north and south of the ecliptic, within which the orbits of the Moon and the principal planets remain.