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Tag: Galileo


Astronomy II

The corrections and original breakthroughs in astronomy were eventually absorbed into the works of Copernicus and the Renaissance astronomers. The greatest Arab achievements in the fields included:

1.                               The Arabs distinguished between astronomy and  astrology for the first time. And astrology was regarded as a key science by the Abbasids.

2.                               Milky Way: Al-Biruni (Persian astronomer 11th century) proposed that the Milky Way was a collection of nebulous stars.

3.                               Ibn Bajjah (Avempace, 12th c.) concluded that the Milky Way was a vast collection of stars but appeared to be a continuous entity, because of the effect of refraction in the Earth’s atmosphere. It wasn’t until 1610 that Galileo studied the Milky Way with a telescope and discovered it was composed of a huge number of faint stars.

4.                               Arab astronomy developed numerous pieces of equipment for measuring angles, such as quadrants… and importantly, astrolabes. These were used for measuring the distance of celestial bodies above the horizon, as well as in determining latitude.





Unlike Chemistry and the life sciences, the Arab quest for the physical sciences came about partly through a need for accurate information… information that related to the Islamic faith. It was necessary to know when to begin and end Ramadan, and when to pray, and in which direction (to Mecca).

Mosques often had their own astronomer, a muqqawit, to determine the time for prayer. They had their own observatories as well. Calendars of prayer times and Ramadan dates, Eid etc were vital, and were created through a knowledge of astronomy. They also had elaborate astronomical charts and instruments for determining the most fortuitous moment to begin a battle or to set out on a journey. All this knowledge in turn fuelled breakthroughs in mathematics, geometry, and geography.

The Abbasids based their research principally on the works of Ptolemy and the work of the seventh century Indian mathematician-astronomer Brahmagupta. The key breakthrough of the Arabs in astronomy was in correcting longstanding errors in the Ptolemaic system. A number of the great Arab polymaths turned their hands to the field, seemingly effortlessly.