Al-Biruni Abu Rayhan Muhammad ibn Ahmad

Abu Rayhan Muhammad ibn Ahmad al-Biruni (Abu Arrayhan Muhammad ibn Ahmad al-Biruni) (973-1048) - Central Asian scholar and lexicographer. Born in the outskirts of the city Kyat, the capital of the ancient state of Khorezm (now part of Uzbekistan). Living under the rule of the Muslim religion are hostile to science, he boldly spoke out against religious outlook. Biruni believed that in nature everything exists and varies according to the laws of nature, not by divine command. Comprehend these laws is only possible with the help of science. For his advanced views Biruni was harassed and was forced to leave three times their homeland and live in exile.

Scientific Papers Biruni cover various fields: astronomy and geography, mathematics and physics, geology and mineralogy, chemistry and botany, history and anthropology, philosophy and philology. Major work (over 40) are devoted to mathematics and astronomy, which was of great practical importance for the economic life of Khorezm - for irrigated agriculture and trade travel. The major tasks of astronomy were improved calendar and methods of orientation on the earth by celestial. It was necessary to be able to as accurately as possible to determine the position of the sun in the sky, . Moon, . stars, . and to measure with the greatest possible accuracy, the so-called fundamental astronomical constants - obliquity of the ecliptic to the equator, . length of the solar and stellar year, etc.,
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And this in turn required the development of mathematics, particularly plane and spherical trigonometry, on the one hand, and improving the tools for accurate observation, on the other. Results and achievements Biruni in all these areas remained unsurpassed for several centuries: the largest mural quadrant - goniometer, . can measure the position of the Sun with an accuracy of 2 ', the most accurate definition of obliquity of the ecliptic to the equator and the secular changes of this magnitude, a new method for determining the radius of the earth - in terms of lowering the horizon as seen from the mountain,
. Biruni almost precisely defined radius of the Earth (more than 6000 km), based on the idea of its spherical shape

. Biruni was adopted and developed progressive ideas of ancient Greek and ancient Indian philosophers to some common problems of astronomy: maintained the same fiery nature of the sun and stars, . in contrast to the dark bodies - planets, stars and the mobility of their huge size compared to Earth, the idea of gravitation,
. Biruni made reasonable doubts the validity of the geocentric Ptolemaic system of the world.

. In the first essay "Chronology of ancient peoples" (1000) Biruni collected and described all known in his day of the calendar employed by various peoples of the world
. Astronomical research presented to them in the "Book of the interpretation of the basic principles of astronomy and other scientific works.