"With Kala-kriya he turned to astronomy — in particular, treating planetary motion along the ecliptic. The topics include definitions of various units of time, eccentric and epicyclic models of planetary motion , planetary longitude corrections for different terrestrial locations, and a theory of “lords of the hours and days” ."

“The greatest of Hindu astronomers and mathematicians, Aryabhata, discussed in verse such poetic subjects as quadratic equations, sines, and the value of π; he explained eclipses, solstices and equinoxes, announced the sphericity of the earth and its diurnal revolution on its axis, and wrote, in daring anticipation of Renaissance science: “The sphere of the stars is stationary, and the earth, by its revolution, produces the daily rising and setting of planets and stars.”

“...he flourished in Kusumapura—near Patalipurta , then the capital of the Gupta dynasty — where he composed at least two works, Aryabhatiya and the now lost Aryabhatasiddhanta. Aryabhatasiddhanta circulated mainly in the northwest of India and, through the Sāsānian dynasty of Iran, had a profound influence on the development of Islamic astronomy. Its contents are preserved to some extent in the works of Varahamihira , Bhaskara I , Brahmagupta , and others. It is one of the earliest astronomical works to assign the start of each day to midnight.”

“Aryabhata is acknowledged as one of the astute astronomers of early India. His school of astronomy is well known and widespread all over India, especially in the South...Of late there is a tendency to spell his name as “Aryabhatta”. While Aryabhata himself mentions Kali 3600 to be the date of his composing the work, some say that Kali 3600 is the date of his birth. A view has been broached that Aryabhata hailed from Kerala.”

“He gives a clue to his date of birth in his Aryabhatiya... The date works out to the end of the Kali year 3600, corresponding to the Saka year 421, the date being 21 March 499 ...and that he composed the Aryabhatiya when he was 25 years old, i.e. in Saka 444 or AD 522. Page 4”

“He hailed from the Asmaka country, which comprised the present South Gujarat and North Maharashtra, through which the rivers Godavari and Narmada flowed. He flourished at Pataliputra in the ancient Magadha country where he composed his works, the 'Aryabhatiya and arya-siddhanta'.”

“In Indian astronomy, the prime meridian is the great circle of the Earth passing through the north and south poles, Ujjayinī and Laṅkā, where Laṅkā was assumed to be on the Earth's equator.”