Surya Siddhanta

The Surya Siddhanta is one of the earliest doctrine or tradition (siddhanta) in archeo-astronomy of the Hindus. Its original version is by an unknown author. It describes the archeo-astronomy theories, principles and methods of the ancient Hindus. This siddhanta is supposed to be the knowledge that the Sun god gave to an Asura called Maya. Asuras were enemies of the Deva, the Gods of Hindus. Asuras were believed to be residents of the nether worlds.

Significant coverage is on kinds of time, length of the year of gods and demons, day and night of god Brahma, the elapsed period since creation, how planets move eastwards and sidereal revolution. The lengths of the Earth's diameter, circumference are also given. Eclipses and color of the eclipsed portion of the moon is mentioned. This explains the archeo-astronomical basis for the sequence of days of the week named after the Sun, Moon, etc. Musings that there is no above and below and that movement of the starry sphere is left to right for Asuras makes interesting reading.

Varahamihira in his Panchasiddhantika contrasts it with four other treatises, besides the Paitamaha Siddhantas (which is more similar to the "classical" Vedanga Jyotisha), the Paulisha and Romaka Siddhantas (directly based on Hellenistic astronomy) and the Vasishta Siddhanta. Citation of the Surya Siddhanta is also found in the works of Aryabhata.

The work referred to by the title Surya Siddhanta has been repeatedly recast. There may have been an early work under that title dating back to the Buddhist Age of India (3rd century BC). The work as preserved and edited by Burgess (1860) dates to the Middle Ages. Utpala, a 10th century commentator of Varahamihira, quotes six shlokas of the Surya Siddhanta of his day, not one of which is to be found in the text now known as the Surya Siddhanta. The present version was modified by Bhaskaracharya during the Middle Ages. The present Surya Siddhanta may nevertheless be considered a direct descendant of the text available to Varahamihira. This article discusses the text as edited by Burgess. For what evidence we have of the Gupta period text, see Pancha-Siddhantika. It has rules laid down to determine the true motions of the luminaries, which conform to their actual positions in the sky. It gives the locations of several stars other than the lunar nakshatras and treats the calculation of solar eclipses. as well as solstices eg.summer solstice 21/06