20.With reference to the computation of the time, the audayika system and ardharaatrika system were devised by ___: [A] Aryabhatta [B] Varahmihira [C] Brahamgupta [D] Nagarjuna
A . Aryabhatt
Aryabahata was the first Indian astronomer to state that the Earth is spherical and rotates on its axis. He went on to explain that the apparent daily east- west motion of the sun, moon, planets, and stars is due to the rotation of the Earth from west to east. He introduced two systems for reckoning time: (1) the audayika system, from sunrise to next sunrise, and (2) the ardharaatrika system, that is, midnight to midnight (sidereal time). The time for one sidereal rotation of the Earth is given as 23h 56m 4.1s (modern value: 23h 56m 4.091s). Responsible for the Indian mathematical renaissance, Aryabhata set the pattern and tone of modern mathematical investigations.