Biruni is regarded as one of the greatest scholars of the medieval Islamic era and was well versed in physics, mathematics, astronomy, and natural sciences, and also distinguished himself as a historian, chronologist and linguist.
If you ask, "who was the first to make experiments related to astronomy?" most people would say Galileo, Ptolemy, or some scientist from the Renaissance. The real answer is Abu Raihan Mohammed Ibn Ahmad Al-Biruni. Born about five centuries before the Renaissance, he proved to be one of the best scientists of all times. At an early age his fame of scholarship went around and when Sultan Mahmood Ghaznawi conquered Ural, Al-Biruni's homeland, he took al-Biruni along with him in his journeys to India several times and so he had the chance to travel all over India for a period of 20 years. Al-Biruni learned Hindu philosophy, mathematics, geography and religion from the Pandits to whom he taught Greek and Arabic science and philosophy. He wrote about his travels through India in his well-known book Kitab-al-Hind which gives a graphic account of the sub-continent.
After he returned to Ural, al-Biruni wrote his famous book Qanun-i-Masoodi which discusses several theories of astronomy, trigonometry, solar, lunar, and planetary movements, and other related topics.
In another book, al-Athar al-Baqia, he attempted a connected account of ancient history of nations and the related geographical knowledge, discussed the rotation of the earth and had given correct values of latitudes and longitudes of various places. He has also made many contributions to several topics of physical and economic geography in this book. At that time people believed in the geocentric theory that is they believed that the earth was in the center and the planets, stars, and sun revolved around it. He clearly knew, 600 years before Galileo, that the earth rotates on its axis daily and moves yearly around the sun. And for the first time in history, he made a scientific explanation of why the sun never sets in the North or South Pole.
He also wrote the book Kitab-al-Saidana which is on Indian medicine. His book, Kitab-al-Jamahir, is about the properties of various precious stones. His book al-Tafhim-li-Awail Sina’at al-Tanjim gives a summary of mathematics and astronomy.
Other Scientific Contributions
Other scientific contributions of his include the accurate densities of 18 different rocks, the mathematical formula for finding exactly when a season starts or ends, and seven different methods to find north and south.
He made a method for the trisection of an angle and other problems that cannot be solved with a ruler and a compass only. He proved that when the speed of sound is compared to the speed of light, the speed of light is very fast. He explained the working of natural springs and artesian wells by the hydrostatic principle of communicating vessels. He observed that flowers have 3,4,5,6, or 8 petals, but never 7 or 9.
Al-Biruni wrote a two hundred books and made a few instruments for astronomy. He died in 1048 CE at the age of 75, after having spent 40 years in gathering knowledge and making his own contributions to it. He has been considered as one of the greatest scientists of Islam, and one of the greatest of all times.