Abu `Ali al-Hasan b . al-Hasan ( or Husayn ) b . al-Haytham al-Basri al-Misri ,

known in mediaeval Latin texts as Alhazen , Avennathan and Avenetan . He was the best physicist and mathematician of his time . Most of his works ( more than one hundred titles ) are devoted to mathematics and physics , but he also wrote on medicine and philosophy .

Ibn al-Haytham was born in Basra in 354 . He went to Egypt during the time of al-Hakim , who reigned 386-411 , and al-Haytham undertook to control the flow of the Nile River . Regulating the water was not possible , and he quit the task and left . He returned to Cairo after the caliph died and earned his living by copying scientific and mathematical manuscripts . He was highly knowledgeable about Greek writers and he edited and criticized Ptolomy . He died in 430 .

Ibn al-Haytham is remembered for his mathematical genius , and is known today for his resolution of Alhazen’s problem: two points , A and B , are fixed on the plane of a circle with centre O and radius R . Find in the circle the point M where the ray of light emitted by A must be reflected in order that it may pass through B . Ibn al-Haytham resolved the problem by making an intersection of an equilateral hyperole with the circle . He demonstrated that of two regular polygons inscribed in the same circle , the one with the greater number of sides also has the larger surface and the larger perimeter .

Ibn al-Haytham explained the use of the camera obscura in observing solar eclipses . He established the theorem of the cotangent in determining the direction of the qibla . Ibn al-Haytham established that the astronomic twilight began or finished when the negative height of the sun reached 19 degrees and proceeding from there , he fixed the height of the atmosphere at 52 , 000 paces . He correctly explained the atmospheric refraction and the augmentation of the apparent diameter of the sun and moon when they are near the horizon . He established that rays of light start from the object to travel towards the eye , and not the reverse . He discovered spherical aberration . He determined that because the Milky Way had no parallax , it was very remote from the earth and did not belong to the atmosphere .

His works:

1 ) Makala fi ‘stkhradj samt al-kibla

2 ) Makala fi hay’at al- `alam

3 ) Kaia fe ‘l-manazir

4 ) makal fi daw’ al-kamar , the ideas on light colors and the celestial movements

5 ) Fi’l-Maraya ‘l-mukrika bi’l-dawa’er

6 ) Fi ‘l-maraya ‘l-mukrika bi ‘l-kutu`