ब्राह्मस्फुटसिद्धान्त (ब्रह्मगुप्त - शून्य, कुट्टक, बीजगणित एवं सम्पूर्ण २१ अध्याय सान्वय सटीक)

MOON'S MEAN MOTION 111 (ii) The same according to the Khaṇḍakhādyaka =29.5305874 days. (iii) The same according to the Brāhma-sphuṭa-siddhānta =29.530582 days. (iv) The same according to Ptolemy=29 da. 31′ 50″ 8″ 20″ in sexagesimal units=29.5305927 days The modern value according to Newcomb and Radaú =29.5305881 days. Hence the Khaṇḍakhādyaka mean length appears to be the closest approximation. The mean sidereal month must have been deduced from the mean synodic month and the year adopted. Hence no compari- son need be made of this element here. We will now consider the sidereal periods, the nodes and the apogee of the Moon. These are shown below :-

According to | Sid. Per. of Moon's Apogee | Sid. per. of the Ascending Node

Āryabhaṭīya | 3231,987079 da. | 6794.749511 da. Khaṇḍakhādyaka | 3231.987844 da. | 6794.750834 da. Brāhma-sphuṭa - Siddhānta | 3232.73411 da. | 6792.25396 da. Ptolemy | 3232.617656 da. | 6796.45571 da. Modern values (Lockyer) | 3232.37543 da. | 6793.39108 da.

Here also the Indian values show a closer approximation to the true values, Brahmagupta's figures representing the nearest approach. Other Constants So far the Indian values of the constants have been more accurate than the Greek ones ; but as to the inclination of the Moon's orbit the Greek value is more accurate than the Indian value. Inclination of the lunar orbit Indian value=4°30′.