Aryabhata: the great Indian scientist of mathematics and astronomy

About fifteen hundred years ago, when most of the world believed that Earth stood still and that eclipses were caused by demons, a young Indian wrote that Earth turns on its axis and that eclipses are caused by shadows. That young man was Aryabhata — one of the greatest mathematicians and astronomers of ancient India.

Who was Aryabhata?

Aryabhata wrote in his work that when 3,600 years of the Kali Yuga had passed, he was 23 years old. By this reckoning he was 23 in 499 CE, so he was born around 476 CE. He lived and worked at Kusumapura, which most scholars place near Pataliputra (today's Patna). Scholars differ about his birthplace.

The Aryabhatiya: a work written at 23

Aryabhata's famous work, the "Aryabhatiya", is written in Sanskrit verse and has four parts:

The whole work has about 121 verses — a great deal of knowledge in very few words. He explained place value as "sthanat sthanam dashagunam", "each place is ten times the one before" — read The story of zero.

Aryabhata's main discoveries

• The value of pi (π): he wrote that if you add 4 to 100, multiply by 8 and add 62,000, you get the "approximate" circumference of a circle 20,000 across — that is, π ≈ 62,832 ÷ 20,000 = 3.1416. He used the word "asanna" (approximate), which suggests he knew it was not the exact value.
• The spinning Earth: he said that just as a person in a moving boat sees the trees on the bank moving the other way, so from the spinning Earth the stars seem to move west.
• The cause of eclipses: he explained that a solar eclipse happens when the Moon's shadow falls on Earth, and a lunar eclipse when Earth's shadow falls on the Moon — read How eclipses happen.
• The length of the year: he gave the year as about 365 days, 6 hours, 12 minutes and 30 seconds, very close to the modern value.
• Moonlight: he wrote that the Moon and the planets shine by the light of the Sun.

Did you know? The mathematical word "sine" comes from Aryabhata's "jya". The Sanskrit "jya" or "jiva" was written "jiba" in Arabic, which was later read as "jaib" (meaning a pocket or fold). In the Latin translation this meaning was written as "sinus" — and from that came "sine".

Honouring Aryabhata

• India's first satellite, launched on 19 April 1975, was named "Aryabhata" after him — read The story of the Aryabhata satellite.
• The "Aryabhatta Research Institute of Observational Sciences" (ARIES) in Nainital and the "Aryabhatta Knowledge University" in Patna are named after him.
• A crater on the Moon has also been named Aryabhata.

Aryabhata's legacy

After Aryabhata, scholars such as Varahamihira, Brahmagupta and Bhaskara I carried his work forward; Bhaskara I wrote a commentary on the Aryabhatiya in 629 CE. Aryabhata's work was translated into Arabic and travelled far. Even today his thinking teaches us to test what our eyes tell us with reason and mathematics.

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