Āryabhaṭa
5th–6th century CE · Kusumapura (Pāṭaliputra) · Astronomy (historical)
Āryabhaṭa was a historical mathematician-astronomer who, by his own account, wrote the Āryabhaṭīya at the age of twenty-three, in 499 CE, at Kusumapura (Pāṭaliputra, near modern Patna). In 121 verses it covers arithmetic, algebra, trigonometry and astronomy.
He taught that the Earth rotates on its axis, explained eclipses by the shadows of the Earth and Moon, gave a value of π close to 3.1416, and used a place-value system of numbers. His work founded a school of astronomy that shaped the Indian calendar and pañcāṅga for centuries. India’s first satellite, launched in 1975, was named after him.
Āryabhaṭīya, 499 CE · Kusumapura (Patna) · Earth’s rotation · π ≈ 3.1416