Almagest is the Latin form of the Arabic name (al-kitabu-l-mijisti, i.e. "The Great Book") of an astronomical treatise proposing the complex motions of the stars and planetary paths, originally written in Greek as μαθηματικἠ σύνταξις (Mathematike Syntaxis, "Mathematical Treatise"; later titled Hè Megalè Syntaxis, "The Great Treatise") by Ptolemy of Alexandria, Egypt. The date of Almagest has recently been more precisely established. Ptolemy set up a public inscription at Canopus in Egypt in 147/148 C.E. The late N. T. Hamilton found that the version of Ptolemy's models set out in the Canopic Inscription was earlier than the version in Almagest. Hence Almagest cannot have been completed before about C.E. 150, a quarter century after Ptolemy began observing [1]. Its geocentric model was accepted as correct for over a thousand years in Arab and European societies. The Almagest is our most important source of information on ancient Greek astronomy. Latin is an ancient [[Indo-European languages|Indo-well as the Roman CEuropean language originally spoken in Latium, the region immediately surrounding Rome. ... The Arabic language ( ), or simply Arabic ( ), is the largest member of the Semitic branch of the Afro-Asiatic language family (classification: South Central Semitic) and is closely related to Hebrew and Aramaic. ... Astronomy, which etymologically means law of the stars, (from Greek: αστρονομία = άστρον + νόμος) is a science involving the observation and explanation of events occurring outside Earth and its atmosphere. ... The Pleiades, an open cluster of stars in the constellation of Taurus. ... The eight planets and three dwarf planets of the Solar System. ... A medieval artists rendition of Claudius Ptolemaeus Claudius Ptolemaeus (Greek: ; c. ... Alexandria Modern Alexandria. ... Canopus (also: Canobus) was an Ancient Egyptian coastal town, located in the Nile Delta. ... This artistic representation of the geocentric model shows signs of the zodiac and the solar system with world at centre. ... This article is about the continent. ... Greek astronomy is the astronomy of those who spoke Greek in classical antiquity. ...

Contents of the Almagest

The Almagest consists of thirteen books. Their subject matter can be summarized as follows:

• Book I contains an outline of Aristotelian cosmology, a set of chord tables, and an introduction to spherical trigonometry.
• Book II covers problems associated with the daily motion attributed to the heavens, namely risings and settings of celestial objects, and the length of daylight.
• Book III covers the motion of the Sun.
• Books IV and V cover the motion of the Moon, lunar parallax, and the sizes and distances of the Sun and Moon relative to the Earth.
• Book VI covers solar and lunar eclipses.
• Books VII and VIII cover the motions of the fixed stars, including precession of the equinoxes. They also contain a star catalogue. The brightest stars were marked of the first magnitude (m = 1), while the faintest were of sixth magnitude (m = 6), the limit of human visual perception (without the aid of a telescope). Each grade of magnitude was considered to be twice the brightness of the following grade (a logarithmic scale). This system is believed to have originated with Hipparchus.
• Book IX addresses general issues associated with creating models for the five naked eye planets, as well as the motion of Mercury.
• Book X covers the motions of Venus and Mars.
• Book XI covers the motions of Jupiter and Saturn.
• Book XII covers stations and retrogradations, which occur when planets appear to pause, then briefly reverse their motion against the background of the zodiac. Ptolemy understood these terms to apply to Mercury and Venus as well as the outer planets.
• Book XIII covers motion in latitude (the deviation of planets from the ecliptic, the apparent path of the Sun through the stars.

Aristotle (Greek: Aristotélēs) (384 BC – March 7, 322 BC) was an ancient Greek philosopher, a student of Plato and teacher of Alexander the Great. ... A chord of a curve is a geometric line segment whose endpoints both lie on the curve. ... Spherical triangle Spherical trigonometry is a part of spherical geometry that deals with polygons (especially triangles) on the sphere and explains how to find relations between the involved angles. ... The Sun is the star of our solar system. ... Bulk composition of the Moons mantle and crust estimated, weight percent Oxygen 42. ... This article or section does not cite its references or sources. ... Earth (IPA: , often referred to as the Earth, Terra, the World or Planet Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ... This article discusses astronomical eclipses. ... For alternate meanings see star (disambiguation) Hundreds of stars are visible in this image taken by the Hubble Space Telescope of the Sagittarius Star Cloud in the Milky Way Galaxy. ... Precession refers to a change in the direction of the axis of a rotating object. ... In astronomy, an equinox is defined as the moment when the sun reaches one of two intersections between the ecliptic and the celestial equator. ... In astronomy, many stars are referred to simply by catalogue numbers. ... // Headline text HEY!! HOW ARE YOU ALL?? Its nice of you to come read this page. ... Hipparchus. ... It has been suggested that Classical Planets be merged into this article or section. ... Prograde motion is the motion of a planetary body in a direction similar to that of other bodies within its system, and is sometimes called direct motion, especially in astrology. ... 360-degree panorama of the night sky with constellations superimposed. ... The plane of the ecliptic is well seen in this picture from the 1994 lunar prospecting Clementine spacecraft. ...

Ptolemy's Cosmos

The cosmology of the Almagest includes five main points, each of which is the subject of a chapter in Book I. What follows is a close paraphrase of Ptolemy's own words from Toomer's translation.

• The celestial realm is spherical, and moves as a sphere.
• The earth is a sphere.
• The earth is at the center of the cosmos.
• The earth is a point with respect to the heavens.
• The earth does not move.

Image File history File links Ptolemaicsystem-small. ... Image File history File links Ptolemaicsystem-small. ...

Ptolemaic Planetary Models

Ptolemy assigned the following order to the planetary spheres, beginning with the innermost: This drawing from an Icelandic manuscript dated around 1750 shows the Earth surrounded by the eight classical spheres. ...

1. Moon
2. Mercury
3. Venus
4. Sun
5. Mars
6. Jupiter
7. Saturn
8. Sphere of fixed stars

Other classical writers suggested different sequences. Plato (c. 427-c. 347 BCE) made the Sun next in order after the Moon, while Martianus Capella (5th century CE) put Mercury and Venus in motion around the Sun. Ptolemy's authority was preferred by most Islamic and late medieval European astronomers. For other uses, see Plato (disambiguation). ... Martianus Minneus Felix Capella was a writer of the late Latin period, whose career flourished some time during the 5th century, before the year 439. ...

Ptolemy inherited from his Greek predecessors a geometrical toolbox and a partial set of models for predicting where the planets would appear in the sky. Apollonius of Perga (c. 262-c. 190 BCE) had introduced the deferent and epicycle and the eccentric deferent to astronomy. Hipparchus (2nd century BCE) had crafted mathematical models of the motion of the Sun and Moon. Hipparchus had some knowledge of Mesopotamian astronomy, and he felt that Greek models should match those of the Babylonians in accuracy. He was unable to create accurate models for the remaining five planets. Apollonius of Perga [Pergaeus] (c. ... In the Ptolemaic system of astronomy, the epicycle (literally: on the cycle in Greek) was a geometric model to explain the variations in speed and direction of the apparent motion of the Moon, Sun, and planets. ... Hipparchus. ... Table of astronomy, from the 1728 Cyclopaedia Astronomy is probably the oldest of the natural sciences, dating back to antiquity, with its origins in the religious practices of pre-history: vestiges of these are still found in astrology, a discipline long interwoven with astronomy, and not completely different from it...

In the Almagest, Ptolemy adopted Hipparchus' solar model, which consisted of a simple eccentric deferent. For the Moon, he began with Hipparchus' epicycle-on-deferent, then added a device that historians of astronomy refer to as a crank mechanism. He succeeded in creating models for the other planets, where Hipparchus had failed, by introducing a third device called the equant. Equant is a mathematical concept developed by Claudius Ptolemy in the 2nd century AD to account for the observed motion of heavenly bodies. ...

The Almagest was written by Ptolemy as a textbook of mathematical astronomy. It explained geometrical models of the planets based on combinations of circles, that could be used to predict the motions of celestial objects. In a later book, the Planetary Hypotheses, Ptolemy explained how to transform his geometrical models into three-dimensional spheres or partial spheres. In contrast to the mathematical Almagest, the Planetary Hypotheses is sometimes described as a book of cosmology.

Impact of the Almagest

Ptolemy's comprehensive treatise of mathematical astronomy superseded most older texts of Greek astronomy. Some were more specialized and thus of less interest; others simply became outdated by the newer models. As a result, the older texts ceased to be copied and were gradually lost. Much of what we know about the work of astronomers like Hipparchus comes from references in the Almagest.

Ptolemy's Almagest became an authoritative work for many centuries, as this 16th-century portrait of him as a Renaissance mathematician shows

Image File history File links Download high-resolution version (1000x1076, 308 KB) Claudius Ptolemäus, Picture of 16th century book frontispiece File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Ptolemy Almagest ... Image File history File links Download high-resolution version (1000x1076, 308 KB) Claudius Ptolemäus, Picture of 16th century book frontispiece File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Ptolemy Almagest ...

The Almagest in the Middle Ages and Renaissance

The first translations into Arabic were made in the 9th century, with two separate efforts, one sponsored by the caliph Al-Ma'mun. By this time, the work was lost in Europe, or only dimly remembered in astrological lore. Consequently, Western Europe rediscovered Ptolemy from translations of Arabic versions. In the twelfth century a Spanish version was produced, later turned into Latin under the patronage of Emperor Frederick II. Another Latin version, this time directly from the Arabic, was produced by Gerard of Cremona, who found his text in Toledo in Spain. Gerard of Cremona was unable to translate many technical terms, even retaining the Arabic Abrachir for Hipparchus. As a means of recording the passage of time the 9th century was that century that lasted from 801 to 900. ... Caliph is the title for the Islamic leader of the Ummah, or community of Islam. ... Abu Jafar al-Mamun ibn Harun (also spelled Almanon and el-Mâmoûn) (786 – October 10, 833) (المأمون) was an Abbasid caliph who reigned from 813 until his death in 833. ... European redirects here. ... Hand-coloured version of the anonymous Flammarion woodcut. ... A common understanding of Western Europe in modern times. ... (11th century - 12th century - 13th century - other centuries) As a means of recording the passage of time, the 12th century was that century which lasted from 1101 to 1200. ... Latin is an ancient [[Indo-European languages|Indo-well as the Roman CEuropean language originally spoken in Latium, the region immediately surrounding Rome. ... Frederick II (December 26, 1194 – December 13, 1250), Holy Roman Emperor of the Hohenstaufen dynasty, was pretender to the title of King of the Romans from 1212, unopposed holder of that monarchy from 1215, and Holy Roman Emperor from 1220 until his death in 1250. ... Gerard of Cremona (Gherardo) (Cremona, Lombardy, c. ... [[ Image:Toledo, Spain Toledo is a city and municipality located in central Spain, about 70 kilometers south of Madrid. ... Gerard of Cremona (Gherardo) (Cremona, Lombardy, c. ...

In the 15th century, a Greek version appeared in Western Europe, and Johannes Müller, better known as Regiomontanus, made an abridged Latin version at the instigation of the brilliant Greek churchman Johannes, Cardinal Bessarion. At the same time, a full translation was made by George of Trebizond. It included a commentary that was as long as the original. The work of translation, done under the patronage of Pope Nicholas V was intended to supplant the old translation. The new manuscripts were a great improvement; the new commentary was not, and aroused much heated criticism. The Pope declined the dedication of the translation, and Regiomontanus' translation had the upper hand for the next century and more. (14th century - 15th century - 16th century - other centuries) As a means of recording the passage of time, the 15th century was that century which lasted from 1401 to 1500. ... Johannes Müller von Königsberg (June 6, 1436 – July 6, 1476), known by his Latin pseudonym Regiomontanus, was an important German mathematician, astronomer and astrologer. ... Johannes Bessarion, or Basilius (c. ... Look up translate in Wiktionary, the free dictionary. ... George of Trebizond (1395- August 12, 1484), Greek philosopher and scholar, one of the pioneers of the revival of letters in the Western world, was born in the island of Crete, and derived his surname Trapezuntios from the fact that his ancestors were from Trebizond. ... Nicholas V, né Tomaso Parentucelli (November 15, 1397 – March 24, 1455) was Pope from March 6, 1447, to his death. ...

Commentaries on Almagest were written by Theon of Alexandria (extant), Pappus (fragments), and Ammonius (lost). Theon (c. ... Pappus of Alexandria is one of the most important mathematicians of ancient Greek time, known for his work Synagoge (“Collection”). He was born at Alexandria of Egypt. ... A commentary written on Ptolemys Almagest. ...

Modern editions

• Two translations of the Almagest have been published in English. The first, by R. Catesby Taliaferro, was included in volume 16 of the Britannica Great Books series. A more recent translation, by G. J. Toomer, Ptolemy's Almagest, Princeton University Press, 1998 (ISBN 0-691-00260-6), is almost universally thought to be superior.

• An older French translation (facing the Greek text), published in two volumes (1813 and 1816) by Nicolas B. Halma, is available online at the Gallica web site[2].

The Great Books The Great Books of the Western World (ISBN 0852295316) is a series of books originally published in the United States in 1952 by Encyclopædia Britannica Inc. ...

References

• James Evans, The History and Practice of Ancient Astronomy, Oxford University Press, 1998 (ISBN 0-19-509539-1)
• Olaf Pedersen, A Survey of the Almagest, Odense University Press, 1974 (ISBN 87-7492-087-1)
• Olaf Pedersen, Early Physics and Astronomy: A Historical Introduction, 2nd edition, Cambridge University Press, 1993 (ISBN 0-521-40340-5)

External links

• Online copy of the star catalog in the Almagest
• Almagest Planetary Model Animations
• Online luni-solar & planetary ephemeris calculator based on the Almagest