Indian astronomy combines algorithms and observation

Herodotus associated a sudden darkness during battle with an eclipse reconstructed for 28 May 585 BCE.

The claim became famous, but surviving evidence does not establish what method he used or whether the prediction was precise.

The eclipse was later said to have prompted peace, illustrating how celestial events acquired political and religious meanings.

Modern calculations verify an eclipse, while the prediction narrative must be treated more cautiously than the astronomical date.

The parameters of the Aryabhatiya are reckoned for mean noon at Ujjain on 21 March 499, providing a precise base date for calculations.

Aryabhata compared the daily westward movement of stars with apparent motion experienced from a moving boat.

His trigonometric methods enabled quantitative work on arcs, shadows, eclipses and celestial coordinates.

Naubakht and Masha'allah calculated an auspicious horoscope for construction of the Abbasid capital on 30 July 762.

Celestial calculation helped legitimize an imperial city and demonstrates the close historical relationship between astronomy and astrology.

The planners' backgrounds reflect the multilingual and multireligious networks that later supported scholarship in Baghdad.