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The first astronomical texts that were translated into Arabic were of Indian [2] and Persian origin. [3] The most notable was Zij al-Sindhind, a zij produced by Muḥammad ibn Ibrāhīm al-Fazārī and Yaʿqūb ibn Ṭāriq, who translated an 8th-century Indian astronomical work after 770, with the assistance of Indian astronomers who were at the court of caliph Al-Mansur.
This is because the distance between Earth and the Sun is not fixed (it varies between 0.983 289 8912 and 1.016 710 3335 au) and, when Earth is closer to the Sun , the Sun's gravitational field is stronger and Earth is moving faster along its orbital path. As the metre is defined in terms of the second and the speed of light is constant for all ...
The Tusi couple, a mathematical device invented by the Persian polymath Nasir al-Din Tusi to model the not perfectly circular motions of the planets. Science in the medieval Islamic world was the science developed and practised during the Islamic Golden Age under the Abbasid Caliphate of Baghdad, the Umayyads of Córdoba, the Abbadids of Seville, the Samanids, the Ziyarids and the Buyids in ...
Voyager 1 surpassed the radial distance from the Sun of Pioneer 10 at 69.4 AU on 17 February 1998, because it was traveling faster, gaining about 1.02 AU per year. [70] On July 18, 2023, Voyager 2 overtook Pioneer 10 as the second most distant human-made object from the Sun. [ 71 ] Pioneer 11 , launched a year after Pioneer 10 , took similar ...
In this case, if the Sun is the source of all the light, under the Ptolemaic system: If Venus is between Earth and the Sun, the phase of Venus must always be crescent or all dark. If Venus is beyond the Sun, the phase of Venus must always be gibbous or full. But Galileo saw Venus at first small and full, and later large and crescent.
In Islamic astronomy, the passing of the Sun over the zenith of Mecca becomes the basis of the qibla observation by shadows twice a year on 27/28 May and 15/16 July. [ 5 ] [ 6 ] At a given location during the course of a day, the Sun reaches not only its zenith but also its nadir , at the antipode of that location 12 hours from solar noon .
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His hypotheses are that the fixed stars and the sun remain unmoved, that the earth revolves about the sun on the circumference of a circle, the sun lying in the middle of the orbit, and that the sphere of the fixed stars, situated about the same centre as the sun, is so great that the circle in which he supposes the earth to revolve bears such ...