## Indian Astronomy - the early impact on the field of astronomy.

**Indian astronomy** has had a huge impact on the science of astronomy. In fact, the study of astronomy in India dates back over four thousand years, and early Indian astronomers are amongst some of the most influential in their field. One of the earliest recorded references to the study of the stars in India can be found in the ‘Rigveda’, a collection of hymns dating back to around 2000 B.C.

### The History of Astronomy in India

Indian astronomy and astrology were closely related. The ancient Indians believed that the position of the planets determined our fortunes, particularly Saturn and Mars. These beliefs formed the basis of modern astrology and horoscopes. However, they held a far more religious significance and one of the earliest texts devoted to astronomy, the Laghada’s Vedanga Jyotisha, stated rules for tracking the movement of the Sun and the Moon for ritualistic purposes. Early Indian astronomy use sidereal calculations. These calculations are based on the stars, and the sidereal period is defined as the time that it takes the object to make one full orbit around the Sun, relative to the stars.

### Early Indian Astronomers and their Discoveries

Many of the earliest Indian astronomers made discoveries that were far ahead of their western counterparts.

**Aryabhatta**

Aryabhatta was born in 476 A.D., and is widely recognized as the father of Indian astronomy. When he was about 25 years old, he presented astronomical and mathematical theories in which the Earth was taken to be spinning on its axis and the periods of the planets were given with respect to the Sun, rather than the stars. These calculations laid the foundations for what we now call the Solar System, with the Sun being at its center. In this, he was way ahead of his time. Aryabhatta also gave numerous measurements that were remarkably accurate for the time, including the Earth's circumference and diameter. He also calculated that the radius of the orbits of planets, in relation to the radius of the Earth and Sun orbit were equal to the length of time it took them to rotate around the Sun, and was the first astronomer to realize that the orbits of the planets around the Sun are ellipses. His studies also led to discovering how lunar and solar eclipses happen and provided calculations to predict their occurrence. Not only was he the first Indian astronomer, but Aryabhatta was also a master mathematician and devised the number ‘zero’, and accurately calculated pi (π) to 4 decimal places.

On April 19, 1975, India sent its first satellite into orbit, named ‘Aryabhatta’.

**Brahmagupta**

Brahmagupta was born in 598 A.D. and was the head of the Indian astronomical observatory at Ujjain. He was the first to use algebra in solving astronomical problems. Brahmagupta developed methods for calculating the movements and positions of numerous planets. He also calculated the circumference of Earth as the equivalent of 36,000 kilometers, which is remarkably close to modern calculations of 40,000 kilometers.

**Bhaskara**

Bhaskara was born in 1114 A.D. and also became the head of the Ujjain observatory. He followed in the footsteps of Brahmagupta with his mathematical genius too, and developed numerous planetary calculations, including the time taken for the Earth to orbit the Sun to 9 decimal places.

**Madhava**

Madhava was born in 1340 A.D. He founded the Kerala School of astronomy and mathematics. This spawned a number of notable astronomers and helped establish Indian astronomy as a world leader in the field between the 14th and 16th centuries.

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