science & techWikipedia476–550 CE · India

Aryabhata, a 5th-century Indian mathematician, proposed that the Earth spins on its axis

the gist

Aryabhata I, who lived from 476 to 550 CE, was among the first of the great mathematician-astronomers of India's classical age. In his Aryabhatiya he worked out an approximation of pi as 3.1416, built a table of sines, and used a place-value system for calculation. He argued that the apparent daily motion of the sky is caused by the Earth rotating on its axis, and he explained eclipses as shadows cast by the Earth and Moon rather than as the work of demons. His ideas were later debated and extended by astronomers across the Islamic world and India.

how it works

Aryabhata used a positional number system like the one we use today, which made long calculations manageable. He compared the sky's daily wheel-like motion with the Earth's spin, so a rotating Earth explained the same observations without moving the stars.

so what

Aryabhata's text shows that Indian astronomers were calculating planetary positions and rotation centuries before the European Renaissance. The Indian space agency named its first satellite after him in 1975, a sign of how central he remains to Indian science.

fun fact

India's first satellite, launched in 1975, was named Aryabhata in his honour.

more on this

watch · 1:44

1:44

Author's Corner | Pradeep Chakravarthy on What Aryabhata Knew About the Earth

Live History India Circle on YouTube ↗

key facts

Born
476
Died
550
Known as
astronomer, mathematician

Facts: Wikidata (CC0)

Adapted from Wikipedia, the free encyclopedia · CC BY-SA 4.0

Photo: Cpjha13, CC BY-SA 4.0, via Wikimedia Commons