Aryabhata And The Start Of Siddhaantic Astronomy In India

With Aryabhateeya began a systematic mathematical treatment of astronomical problems. Neelakantha Somayaaji & others of the Kerala school (14th-17th century CE) later made important contributions

- M S Sriram

Aryabhateeya was composed in 499 CE by Aryabhata in Kusumapura, which is identified with Pataliputra (essentially modern Patna). This text heralded the advent of siddhaantic astronomy in India, which gives a systematic mathematical treatment of astronomical problems. Aryabhateeya is very brief and has only 121 stanzas. It has four parts, one of which is devoted to mathematics. It is in this part that the computation of the sine function (jyaa in India) is discussed. The jyaa is far more convenient than the Greek chord for astronomical computations, and is essentially the modern ‘sin theta’.

Aryabhateeya states: “The globe of the Earth stands (supportless) at the centre of the circular frame of asterisms surrounded by the orbits (of the planets); it is made up of water, earth, fire and air and is spherical.” It is one of the earliest texts anywhere to discuss the rotation of the earth: “Just as a man in a boat moving forward sees the stationary objects as moving backward, just so are the stationary stars seen by people at Lanka (on the equator), as moving exactly towards the west.”

Aryabhateeya introduces the concept of a mahaayuga of 43,20,000 years, in which all the planets (the Sun and the Moon are also considered as planets) make an integral number of revolutions around the earth. The number of revolutions in a