His Planetary Hypotheses went beyond the mathematical model of the Almagest to present a physical realization of the universe as a set of nested spheres, in which he used the epicycles of his planetary model to compute the dimensions of the universe.

Although the extremely accurate model in the Almagest relied solely on geometrical constructions, in his Planetary Hypotheses Ptolemy proposed both a physical structure of the universe and causes of the celestial motions.

In contrast to the mathematical Almagest, the Planetary Hypotheses is sometimes described as a book of cosmology.

It is widely accepted that Copernicus's De revolutionibus followed the outline and method set by Ptolemy in his Almagest and employed geometrical constructions that had been developed previously by the Maragheh school in his heliocentric model, and that Galileo's mathematical treatment of acceleration and his concept of impetus rejected earlier medieval analyses of motion, rejecting by name ; Averroes, Avempace, Jean Buridan, and John Philoponus ( see Theory of impetus ).

When the Greek astronomer Ptolemy's Almagest was translated from Greek to Arabic, the translator Johannitius ( following Alberuni ) did not know the Greek word and rendered it as the nearest-looking Arabic word, writing العصى ذات الكلاب in ordinary unvowelled Arabic text " al -` aşā dhāt al-kullāb ", which means " the spearshaft having a hook ".

There is little evidence on the subject of Ptolemy's ancestry, apart from what can be drawn from the details of his name ( see above ); however modern scholars refer to Abu Ma ’ shar ’ s account as erroneous, and it is no longer doubted that the astronomer who wrote the Almagest also wrote the Tetrabiblos as its astrological counterpart.

* Ptolemy's Almagest, Translated and annotated by G. J. Toomer.

George of Trebizond who was Bessarion's philosophical rival had recently produced a new Latin translation of Ptolemy's Almagest from the Greek, which Bessarion, correctly, regarded as inaccurate and badly translated, so he asked Peuerbach to produce a new one.

Other famous Arabic star catalogues include Alfraganus ' A compendium of the science of stars ( 850 ) which corrected Ptolemy's Almagest ; and Azophi's Book of Fixed Stars ( 964 ) which described observations of the stars, their positions, magnitudes, brightness and colour, drawings for each constellation, and the first descriptions of Andromeda Galaxy and the Large Magellanic Cloud.

* The Ptolemaic model of planetary motion: Based on the geometrical model of Eudoxus of Cnidus, Ptolemy's Almagest, demonstrated that calculations could compute the exact positions of the Sun, Moon, stars, and planets in the future and in the past, and showed how these computational models were derived from astronomical observations.

The construction of the zodiac is described in Ptolemy's Almagest ( 2nd century AD ).

* This is also the approximate date of completion of Ptolemy's monumental work Almagest.

He gains some renown for his version of Euclid's Elements and his commentaries on Ptolemy's Almagest.

* 1150s – Gerard of Cremona translates Ptolemy's Almagest from Arabic into Latin, eventually leading to its adoption by the Catholic Church as an approved text.

* late 16th century — Tycho Brahe updates Ptolemy's Almagest

According to Ptolemy's Almagest, Hipparchus measured the longitude of Spica and other bright stars.

In Ptolemy's Almagest, Coma Berenices is not listed as a distinct constellation.

The star lists in the Astronomia are in exactly the same order as in Ptolemy's Almagest reinforcing the idea of a 2nd century compilation.

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 the Almagest.

Ptolemy's Almagest became an authoritative work for many centuries.

The first, by R. Catesby Taliaferro of St. John's College in Annapolis, Maryland, was included in volume 16 of the Great Books of the Western World ; the second, by G. J. Toomer, Ptolemy's Almagest in 1998 ;

* Ptolemy's Almagest.

He began to work up Ptolemy's Almagest and Alhazen's On the Configuration of the World.

Neither Ptolemy's Almagest nor Al Sufi's Book of Fixed Stars noted this nebula, even though they both listed patches of nebulosity elsewhere in the night sky ; nor did Galileo mention it, even though he also made telescopic observations surrounding it in 1610 and 1617.

The modern almanac differs from Babylonian, Ptolemaic and Zij tables in the sense that " the entries found in the almanacs give directly the positions of the celestial bodies and need no further computation ", in contrast to the more common " auxiliary astronomical tables " based on Ptolemy's Almagest.

One of his most famous translations is of Ptolemy's Almagest from Arabic texts found in Toledo.

There he learned Arabic, initially, so that he could read Ptolemy's Almagest, which had a traditionally high reputation among scholars, but which, before his departure to Castile, was not yet known in Latin translation.

In the 16th century, Nicolaus Copernicus De revolutionibus presented a full discussion of a heliocentric model of the universe in much the same way as Ptolemy's Almagest had presented his geocentric model in the 2nd century.

To approximate his tropical year Hipparchus created his own lunisolar calendar by modifying those of Meton and Callippus in On Intercalary Months and Days ( now lost ), as described by Ptolemy in the Almagest III. 1 ( Toomer 1984, p. 139 ).

One of Riccioli's most significant works was his 1651 Almagestum Novum ( New Almagest ), an encyclopedic work consisting of over 1500 folio pages ( 38 cm x 25 cm ) densely packed with text, tables, and illustrations.

Al-Biruni's work, The Keys of Astronomy, lists a number of those works, which can be classified into studies as part of commentaries on Ptolemy's Almagest as in the works of al-Nayrizi and al-Khazin where each demonstrated particular cases of Menelaus ' theorem that led to the sine rule, or works composed as independent treatises such as:

With the revival of Hellenistic astronomy which took place during the Islamic Golden Age, Jews were intimately connected, and the Almagest is said to have been translated by Sahal ibn Tabari as early as 800, while one of the earliest independent students of astronomy among the Arabs was Mashallah ibn Athari ( 754-873 ?).

There are in The Almagest no rules for determining in advance whether a new epicycle will be required for dealing with abberations in lunar, solar, or planetary behavior.

Perhaps for no other reason than the association of name, the 9th century Persian astronomer Abu Ma ' shar assumed Ptolemy to be member of Egypt's royal lineage, stating that the ten kings of Egypt who followed Alexander were wise " and included Ptolemy the Wise, who composed the book of the Almagest ".

That it did not quite attain the unrivaled status of the Almagest was perhaps because it did not cover some popular areas of the subject, particularly electional astrology ( interpreting astrological charts for a particular moment to determine the outcome of a course of action to be initiated at that time ), and medical astrology, which were later adoptions.

** the Almagest which becomes the basis for western and Middle Eastern astronomy until the time of Copernicus and Kepler ;

The most significant of these was the Almagest, which remained the most important book on predictive geometrical astronomy for some 1400 years.

These finally evolved into the New Kingdom months, which in turn gave rise to the Hellenized names that were used for chronology by Ptolemy in his Almagest, and by others.

They were sold to the general public as well as to students, and by 1941 the St. John's College bookshop was famous as the only source for English translations of works such as Copernicus's De revolutionibus orbium coelestium, St. Augustine's De Musica, and Ptolemy's Almagest.

* Constructions for the regular pentagon were described both by Euclid ( Elements, ca 300 BC ), and by Ptolemy ( Almagest, ca AD 150 ).

As the frontispiece of the New Almagest illustrates ( see figure at right ), Riccioli favoured a modified version of Tycho Brahe's system ; here is how he described the system that " came to mind " when he was in Parma: " it shares everything with the Tychonian system, except the orbits of Saturn and Jupiter ; for their center was not the Sun, but Earth itself ".

However, translations of arguments of the New Almagest, and discussions of the arguments to any extent by more modern writers are rare: only for three arguments of the 126 are such translations and discussions readily available.

The ancient geometers are not done yet, for if the fifth vertex of the pentagon is marked as E and FE and BF are joined ( with FE = BF = z ), then cyclic quadrilateral EFBA will be formed with diagonals length d ( diameter ) and b. Applying the ' Almagest ' theorem yet again:

His Almagest defined the method and subject matter of future astronomical research and the Ptolemaic system became the dominant model for the motions of the heavens.

The triquetrum ( derived from the Latin tri-(" three ") and quetrum (" cornered ")) was the medieval name for an ancient astronomical instrument first described by Ptolemy in the Almagest ( V. 12 ).

In Ptolemy's Almagest, for example, he cites ( Almagest VII 3, H25 ) observations by Timocharis in the 47th year of the first Callippic cycle ( 283 BC ), when on the eighth of Anthesterion, the Pleiades were occulted by the Moon.

Ptolemy's Almagest was an authoritative text on astronomy for more than a thousand years, and the Tetrabiblos, its companion volume, was equally influential in astrology, the study of the effects of astronomical cycles on earthly matters.

But whilst the Almagest as an astronomical authority was superseded by acceptance of the heliocentric model of the solar system, the Tetrabiblos remains an important theoretical work for astrology.

There is no firmly established date for the compilation of the Tetrabiblos but Ptolemy discloses in his ' Introductory Address ' that he wrote his astrological treatise after completing his astronomical one: the Almagest.

Within his Almagest Ptolemy explains that he had access to eclipse records kept for 900 years since the beginning of the reign of king Nabonassar ( 747 BC ).

Ptolemy's Almagest, although a brilliant treatise on theoretical astronomy combined with a practical handbook for computation, nevertheless includes many compromises to reconcile discordant observations.