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The table of chords, created by the Greek astronomer, geometer, and geographer Ptolemy in Egypt during the 2nd century AD, is a trigonometric table in Book I, chapter 11 of Ptolemy's Almagest, [1] a treatise on mathematical astronomy. It is essentially equivalent to a table of values of the sine function.
The following is a list of astronomers, astrophysicists and other notable people who have made contributions to the field of astronomy.They may have won major prizes or awards, developed or invented widely used techniques or technologies within astronomy, or are directors of major observatories or heads of space-based telescope projects.
Astronomy (from the Greek ἀστρονομία from ἄστρον astron, "star" and -νομία -nomia from νόμος nomos, "law" or "culture") means "law of the stars" (or "culture of the stars" depending on the translation).
The order of the planets around the Sun and their periodicity. Chapters 12–14 give theorems for chord geometry as well as a table of chords. Book II describes the principles of spherical astronomy as a basis for the arguments developed in the following books and gives a comprehensive catalogue of the fixed stars. [5]
In Greek antiquity the ideas of celestial spheres and rings first appeared in the cosmology of Anaximander in the early 6th century BC. [7] In his cosmology both the Sun and Moon are circular open vents in tubular rings of fire enclosed in tubes of condensed air; these rings constitute the rims of rotating chariot-like wheels pivoting on the Earth at their centre.
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He became a chief astronomer to the Sultan in 1571 a year after he came to Istanbul, replacing Mustafa ibn Ali al-Muwaqqit. [15] [3] Taqī al-Dīn maintained a strong bond with the people from the Ulama and statesmen. He would pass on information to Sultan Murad III who had an interest in astronomy but also in astrology.