Habash al-Hasib al-Marwazi (9th-century muslim astronomer)

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Habash al-Hasib al-Marwazi died after 869 AD He flourished in Baghdad . He was a great astronomer, geographer, and mathematician He described first time Trigonometric ratios: SIN, COS, TAN & COT. He made observations from 825 to 835, and compiled three astronomical tables: Habash gives us the first instance of a determination of time by an altitude (in this case, of the sun); a method which was generally adopted by Muslim astronomers. In 830, he seems to have introduced the notion of "shadow," umbra (versa), equivalent to our tangent in trigonometry, and he compiled a table of such shadows which seems to be the earliest of its kind. He also introduced the cotangent, and produced the first tables for it.

Transcript of Habash al-Hasib al-Marwazi (9th-century muslim astronomer)

Page 1: Habash al-Hasib al-Marwazi (9th-century muslim astronomer)

Habash al-Hasib al-Marwazi died after 869 AD

He flourished in Baghdad . He was a great astronomer, geographer, and mathematician He described first time Trigonometric ratios: SIN, COS, TAN & COT.

He made observations from 825 to 835, and compiled three astronomical tables: Habash gives us the first instance of a determination of time by an altitude (in this case, of the sun); a method which was generally adopted by Muslim astronomers.

In 830, he seems to have introduced the notion of "shadow," umbra (versa), equivalent to our tangent in trigonometry, and he compiled a table of such shadows which seems to be the earliest of its kind.

He also introduced the cotangent, and produced the first tables for it.

Page 2: Habash al-Hasib al-Marwazi (9th-century muslim astronomer)

The Book of Bodies and Distances

Al-Hasib conducted various observations at the Al-Shammisiyyah observatory in Baghdad and estimated a number of geographic and astronomical values.

He compiled his results in The Book of Bodies and Distances, in which some of his results included the following:

Earth

Earth's circumference: 20,160 miles (32,444 km)

Earth's diameter: 6414.54 miles (10323.201 km)

Earth radius: 3207.275 miles (5161.609 km)

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Moon

Moon's diameter: 1886.8 miles (3036.5 km)

Moon's circumference: 5927.025 miles (9538.622 km)

Radius of closest distance of Moon: 215,208;9,9 (sexagesimal) miles

Half-circumference of closest distance of Moon: 676,368;28,45,25,43 (sexagesimal) miles

Radius of furthest distance of Moon: 205,800;8,45 (sexagesimal) miles

Diameter of furthest distance of Moon: 411,600.216 miles (662,406.338 km)

Circumference of furthest distance of Moon: 1,293,600.916 miles (2,081,848.873 km)

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Sun

Sun's diameter: 35,280;1,30 miles (56,777.6966 km)

Sun's circumference: 110,880;4,43 miles (178,444.189 km)

Diameter of orbit of Sun: 7,761,605.5 miles (12,491,093.2 km)

Circumference of orbit of Sun: 24,392,571.38 miles (39,256,038 km)

One degree along orbit of Sun: 67,700.05 miles (108,952.67 km)

One minute along orbit of Sun: 1129.283 miles (1817.405 km)