The Sun Treatise

It is proven that the astronomical observations of our scholars are more accurate than the observations of Ptolemy or Kepler, and are thus independent from them.

Similarly, if one compares the apogees original: "mandochchas"; the points in an orbit farthest from the Earth, the nodes original: "patas"; the points where a planet's orbit crosses the ecliptic, and other astronomical constants, it becomes evident that the constants accepted by our ancient masters are, for the most part, closer to reality. Therefore, it is established that our system of Jyotish traditional Indian astronomy and astrology is not a shadow of Ptolemy or any other foreign astronomy, but is instead independent. These points are illustrated throughout the Vijnana-Bhashya a scientific commentary on the text.

Regarding this matter, there is great disagreement among scholars. The composition date stated in this book is not logically sound. For if it had continued in this same form from such an ancient time—two million, one hundred and sixty-five thousand years ago—then why would the question have arisen five thousand years ago during the Mahabharata era the period of the great Indian epic war? In the court of the Emperor Duryodhana, where the greatest scholars of the time were present, why would the question have been raised as to when the Pandavas’ fourteen-year exile would be completed? Based on the answer given by Bhishma the grand patriarch of the Kuru dynasty regarding this matter, it does not appear that they were familiar with astronomical calculations from a text like the Surya Siddhanta at that time.

However, there is no doubt that the original form of this text predates Varahamihira a 6th-century polymath by a long time, and it is possible that the version seen in the Panchasiddhantika Varahamihira's "Five Treatises" on astronomy is not the original version, but rather a revision made by Varahamihira. Yet it is surprising that Aryabhata (476 CE) has not mentioned it anywhere in his own work; from this, one might infer that it was composed around the same time as the Aryabhatiya Aryabhata's primary astronomical work.

The form of the Surya Siddhanta presented by Varahamihira differs from the current Surya Siddhanta, in which details about the precession of the equinoxes original: "ayana-chalana"; the slow change in the orientation of Earth's rotational axis were added later. If the precession of the equinoxes had been discussed in the Surya Siddhanta before Varahamihira, he would surely have included it somewhere in the Panchasiddhantika, and would not have been satisfied with merely writing that in ancient times the solstitial point was in the Ashlesha lunar mansion and is now in Punarvasu. Even in the version of the Surya Siddhanta existing during the time of Brahmagupta (628–665 CE), there was no mention of the precession of the equinoxes, because if there had been, Brahmagupta would certainly have discussed it.

This matter must have been added shortly before the time of Bhaskaracharya the 12th-century mathematician, also known as Bhaskara II, but even then, not in the form we see today, as Bhaskaracharya himself expressed doubts about its accuracy. Therefore, it is proven that the original form of the current Surya Siddhanta is indeed the one given in the Panchasiddhantika, which existed even before Varahamihira, or that the version of the Surya Siddhanta by Varahamihira is its revised form, and later, astronomers made corrections to it from time to time... corrections were made to keep calculations aligned with observed reality