Zodiac, in astronomy and astrology, a belt around the heavens extending 9° on either side of the ecliptic, the plane of Earth’s orbit and of the Sun’s apparent annual path. The orbits of the Moon and of the principal planets also lie entirely within the zodiac. The 12 astrological signs of the zodiac are each considered to occupy 1/12 (or 30°) of its great circle. These signs no longer correspond to the astronomical constellations in which the Sun actually appears. The constellations are irregular in size and shape, and the Sun regularly passes through one constellation (Ophiuchus) that is not considered a member of the zodiac.
Because most of the constellations through which the ecliptic passes represent animals, the ancient Greeks called its zone zōdiakos kyklos, “circle of animals,” or ta zōdia, “the little animals.” The size and number of zodiacal constellations varied in antiquity and became fixed only with the development of mathematical astronomy. The list below gives the constellations of the zodiac, with the dates of the Sun’s passage through them in the era when their boundaries were fixed. These dates are still used for the astrological signs, though precession of the equinoxes has shifted the constellations eastward; e.g., on January 1 the direction of the sun is now in Sagittarius instead of Capricornus. The history of the symbols is unknown; they seem to appear first in Greek manuscripts of the late Middle Ages.
♈ Aries (Ram): March 21–April 19
♉ Taurus (Bull): April 20–May 20
♊ Gemini (Twins): May 21–June 21
♋ Cancer (Crab): June 22–July 22
♌ Leo (Lion): July 23–August 22
♍ Virgo (Virgin): August 23–September 22
♎ Libra (Balance): September 23–October 23
♏ Scorpius (Scorpion): October 24–November 21
♐ Sagittarius (Archer): November 22–December 21
♑ Capricornus (Goat): December 22–January 19
♒ Aquarius (Water Bearer): January 20–February 18
♓ Pisces (Fish): February 19–March 20
Almagest, astronomical manual written about 150 CE by Ptolemy (Claudius Ptolemaeus of Alexandria). It served as the basic guide for Islamic and European astronomers until about the beginning of the 17th century. Its original name was Mathematike Syntaxis (“The Mathematical Arrangement”); Almagest arose as an Arabic corruption of the Greek word for “greatest” (megiste). It was translated into Arabic in the late 8th and early 9th centuries and then from Arabic to Latin by Gerard of Cremona in the last half of the 12th century. Beginning in the 15th century, the Greek text circulated widely in Europe, although the Latin translations from Arabic continued to be more influential.
The Almagest is divided into 13 books. Book 1 gives arguments for a geocentric spherical cosmos and introduces the necessary trigonometry, along with a trigonometry table, that allowed Ptolemy in subsequent books to explain and predict the motions of the Sun, Moon, planets, and stars. Book 2 uses spherical trigonometry to explain cartography and astronomical phenomena (such as the length of the longest day) characteristic of various localities. Book 3 deals with the motion of the Sun and how to predict its position in the zodiac at any given time, and Books 4 and 5 treat the more difficult problem of the Moon’s motion. Book 5 also describes the construction of instruments to aid in these investigations. The theory developed to this point is applied to solar and lunar eclipses in Book 6.
Books 7 and 8 mainly concern the fixed stars, giving ecliptic coordinates and magnitudes for 1,022 stars. This star catalog relies heavily on that of Hipparchus (129 BCE), and in the majority of cases Ptolemy simply converted Hipparchus’s description of the location of each star to ecliptic coordinates and then shifted these values by a constant to account for precession over the intervening centuries. These two books also discuss the construction of a star globe that adjusts for precession. The remaining five books, the most original, set forth in detail geometric models for the motion of the five planets visible to the naked eye, together with tables for predicting their positions at any given time.
Please complete the following Coordinates to locate the final container:
(Please note: Substitute ZERO for TEN)
N42 AB.CDE x W083 FG.HIJ
A: ♉ Taurus | B: ♌ Leo
C: ♑ Capricornus | D: ♈ Aries | E: ♏ Scorpius
F: ♈ Aries | G: ♏ Scorpius
H: ♊ Gemini | I: ♎ Libra | J: ♊ Gemini
Enjoy!