Aryabhatta is the first of the great astronomers of the classical age of
India. He was born in Kerala, South India in 476 AD but later lived in Kusumapura,
which his commentator Bhaskara I (629 AD) identifies with pataliputra (modern Patna)
in Bihar. His first name “Arya” is hardly a south Indian name while “Bhatt” (or
Bhatta) is a typical north Indian name even found today specially among the trader
Aryabhatta studied at the University of Nalanda. One of his major works was
Aryabhatiya written in 499 AD. His book aryabhatiya covers 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. Aryabhatta believes that the
moon and planets shine by reflected sunlight and he also believes that the orbits
of the planets are ellipses. He correctly explains the causes of eclipses of the
Sun and the Moon. His value for the length of the year at 365 days 6 hours 12 minutes
30 seconds is remarkably close to the true value which is about 365 days 6 hours.
In this book, the day was reckoned from one sunrise to the next, whereas in his
Aryabhata-siddhanta he took the day from one midnight to another. There was also
difference in some astronomical parameters.
Aryabhatta was the first to explain how the Lunar Eclipse and the Solar Eclipse
happened. Aryabhatta also gave close approximation for Pi. In the Aryabhatiya, he
wrote-“Add 4 to 100, multiply by 8, then add 62000 and then divided by 20000. The
result is approximately the circumference of a circle of diameter twenty thousand.
By this rule the relation of the circumference to diameter is given.” In other words,
p ~ 62832/20000= 3.1416, correct to four rounded – off decimal places. Aryabhatta
was the first astronomers to make an attempt at measuring the earth’s circumference.
Aryabhata accurately calculated the earth’s circumference as 24835 miles, which
was only 0.2 % smaller than the actual value of 24,902 miles. This approximation
remained the most accurate for over a thousand years.
Aryabhatiya was translated into Latin in the 13th century. Through this translation,
European mathematician got to know methods for calculating the areas of triangles,
volumes of spheres as well as square and cube root. Aryabhatta’s ideas about eclipses
and the sun being the sources of moonlight may not have caused much of an impression
on European astronomers as by then they had come to know of these facts through
the observations of Copernicus and Galileo. Considering that Aryabhatta discovered
these facts 1500 years ago, and 1000 years before Copernicus and Galileo makes him
an early pioneer of this field. Aryabhatta – Siddhanta were reliable for practical
purpose of fixing the Panchanga (Hindu Calendar) . He died in India.