Zodiac Symbols

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In both astrology and historical astronomy, the **zodiac** (Greek: ζῳδιακός, *zōidiakos*) is a circle of twelve 30° divisions of celestial longitude that are centered upon the ecliptic, the apparent path of the Sun across the celestial sphere over the course of the year. The paths of the Moon and visible planets also remain close to the ecliptic, within the belt of the zodiac, which extends 8-9° north or south of the ecliptic, as measured incelestial latitude. Because the divisions are regular, they do not correspond exactly to the boundaries of the twelve constellations after which they are named.

Historically, these twelve divisions are called signs. Essentially, the zodiac is a celestial coordinate system, or more specifically an ecliptic coordinate system, which takes the ecliptic as the origin of latitude, and the position of the Sun at vernal equinox as the origin of longitude.

## ***Usage of Zodiac Symbols***

Zodiac Symbols were used in the Roman Era, based on concepts inherited by Hellenistic

astronomy from Babylonian astronomy of the Chaldean period (mid-1st millennium BC), which, in turn, derived from an earlier system of lists of stars along the ecliptic. The construction of the zodiac is described in Ptolemy's vast 2nd century AD work, the *Almagest*.

The term *zodiac* derives from Latin *zōdiacus*, which in its turn comes from the Greek ζῳδιακὸς κύκλος (*zōdiakos kyklos*), meaning "circle of animals", derived from ζῴδιον (*zōdion*), the diminutive of ζῷον (*zōon*) "animal". The name is motivated by the fact that half of the signs of the classical Greek zodiac are represented as animals (besides two mythological hybrids).

Although the zodiac remains the basis of the ecliptic coordinate system in use in astronomy besides the equatorial one, the term and the names of the twelve signs are today mostly associated with horoscopic astrology. 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 eight arc degrees above and below the ecliptic. The zodiac of a given planet is the band that contains the path of that particular body; e.g., the "zodiac of the Moon" is the band of five degrees above and below the ecliptic. By extension, the "zodiac of the comets" may refer to the band encompassing most short-period comets.

### ***Early History***

The division of the ecliptic into the zodiacal signs originates in Babylonian ("Chaldean") astronomy during the first half of the 1st millennium BC, likely during Median/"Neo-Babylonian" times (7th century BC). The classical zodiac is a modification of the MUL.APIN catalogue, which was compiled around 1000 BC. Some of the constellations can be traced even further back, to Bronze Age (Old Babylonian) sources, including Gemini "The Twins", from MAŠ.TAB.BA.GAL.GAL "The Great Twins", and Cancer "The Crab", from AL.LUL "The Crayfish", among others.

Babylonian astronomers at some stage during the early 1st millennium BC divided the ecliptic into twelve equal *zones* of celestial longitude to create the first known celestial coordinate system: a coordinate system that boasts some advantages over modern systems (such as theequatorial coordinate system). The Babylonian calendar as it stood in the 7th century BC assigned each month to a sign, beginning with the position of the Sun at vernal equinox, which, at the time, was depicted as the Aries constellation ("Age of Aries"), for which reason the first sign is still called "Aries" even after the vernal equinox has moved away from the Aries constellation due to the slow precession of the Earth's axis of rotation.

Because the division was made into equal arcs, 30° each, they constituted an ideal system of reference for making predictions about a planet's longitude. However, Babylonian techniques of observational measurements were in a rudimentary stage of evolution and it is unclear whether they had techniques to define in a precise way the boundary lines between the zodiacal signs in the sky. Thus, the need to use stars close to the ecliptic (±9° of latitude) as a set of observational reference points to help positioning a planet within this ecliptic coordinate system. Constellations were given the names of the signs and asterisms could be connected in a way that would resemble the sign's name. Therefore, in spite of its conceptual origin, the Babylonian zodiac became sidereal.

In Babylonian astronomical diaries, a planet position was generally given with respect to a zodiacal sign alone,

less often in specific degrees within a sign. When the degrees of longitude were given, they were expressed with reference to the 30° of the zodiacal sign, i.e., not with a reference to the continuous 360° ecliptic. To the construction of their mathematical ephemerides, daily positions of a planet were not as important as the dates when the planet crossed from one zodiacal sign to the next.

Knowledge of the Babylonian zodiac is also reflected in the Hebrew Bible. E. W. Bullinger interpreted the creatures appearing in the books of Ezekiel and Revelation as the middle signs of the four quarters of the Zodiac,[14][15] with the Lion as Leo, the Bull is Taurus, the Man representing Aquarius and the Eagle representing Scorpio.[16] Some authors have linked thetwelve tribes of Israel with the twelve signs. 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.[17][18] 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.

### ***Hellenistic and Roman Era***

The Babylonian star catalogs entered Greek astronomy in the 4th century BC, via Eudoxus of Cnidus. 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. Hellenistic astrology derived in part from Babylonian and Egyptian astrology.[21] Horoscopic astrology first appeared in Ptolemaic Egypt. The Dendera zodiac, a relief dating to ca. 50 BC, is the first known depiction of the classical zodiac of twelve signs.

Particularly important in the development of Western horoscopic astrology was the astrologer and astronomer Ptolemy, whose work *Tetrabiblos l*aid the basis of the Western astrological tradition. 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. Ptolemy lived in the 2nd century AD, three centuries after the discovery of the precession of the equinoxes by Hipparchus around 130 BC. Hipparchus's lost work on precession never circulated very widely until it was brought to prominence by

Ptolemy, and there are few explanations of precession outside the work of Ptolemy until late Antiquity, by which time Ptolemy's influence was widely established. Ptolemy clearly explained the theoretical basis of the western zodiac as being a tropical coordinate system, by which the zodiac is aligned to the equinoxes and solstices, rather than the visible constellations that bear the same names as the zodiac signs.

## ***The Twelve Zodiac Signs***

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