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The Surya Siddhanta is an important astronomical text, which was written in the 5th century CE in India. It is one of the few texts which provide information about the Syntaxis school of astronomy from Alexandria. The text combines theories from earlier Indian sources with the principles and techniques of Hellenistic astronomy. The Surya Siddhanta was rediscovered again in the 20th century by Jyotish Vidya VachaspathY

What is the Meaning of Surya Siddhanta?

Surya Siddhanta is the ‘astronomical treatise based on the sun’. It is named after the sun, because the alignment of the sun and stars was the basic technique in this text. Siddhanta is a Sanskrit word, which means ‘conclusion’ or ‘finding’. Hence, the Surya Siddhanta is an astronomical conclusion based on the sun.

Importance of Surya Siddhanta

The importance of the Surya Siddhanta lies in the fact that it is a Hindu astronomical text from the 5th century CE, which was written in the mode of the Syntaxis school of astronomy from Alexandria. The Surya Siddhanta was rediscovered again in the 20th century by Jyotish Vidya VachaspathY. The Surya Siddhanta discusses astronomy, the calendar, and time, particularly the time at which various Vedic sacrifices should be performed. This text also discusses the rising and setting times of the sun and the moon, their path across the sky, and their relationships with various stars, planets, and zodiacal signs. In this sense, the Surya Siddhanta is a complex and comprehensive treatise on astronomical phenomena.

Equinoxes and Solstice inSurya Siddhanta

The vernal equinox (Brahma paksha pahara) marks the beginning of the Hindu calendar. The sun, as it travels through the twelve zodiac signs, passes through three equinoctial points in each sign – the first point marks the beginning of the sign (equinox) and the third marks the end of the sign (solstice). The winter solstice (mahapaksha pahara) marks the end of the year.

Moon phase (tithi) and its durationin Surya Siddhanta

Temporal durations, such as the duration of the rising and setting of the sun, are measured in tithis, which are lunar days. The tithis are determined by the position of the full moon. The tithis are grouped into lunar months called paksha, which are further grouped into two seasons each. The seasons are named after the sun signs and are called the solar months. There are two seasons for each solar month. The seasons are governed by the path that the sun travels in the sky. In autumn, the path of the sun is from south to north. In winter, the path of the sun is from north to south. The sun’s path in the sky is the vertical line passing through the equinoxes and solstices. The seasons are the horizontal lines drawn midway between the equinoxes and solstices. The divisions of the seasons are indicated by the moon’s path in the sky, which is the horizontal line passing through the full moons.

360 Day Lunar Calendar

The Surya Siddhanta lists a 360-day calendar as an alternative to the standard 354-day calendar. The 360-day calendar is formed by adding two special days (dvisapta) to the standard calendar. These are amavasya, the new-moon day, and purnima, the full-moon day. The addition of two special days creates two extra months in each year. There are two ways to calculate the position of the special days. One is to add the two special days to the first day of the first month. The other is to add them to the first day of spring. The first method produces a 354-day calendar, whereas the second method produces a 360-day calendar. The Surya Siddhanta discusses the second method for calculating the position of the special days. This method creates a 360-day calendar, which is a continuous calendar. The standard calendar, on the other hand, is a discontinuous calendar, in which the months are not continuous.

Mathematics in Surya Siddhanta

The Surya Siddhanta also provides information about time and calendars. The text discusses the rising and setting times of the sun and the moon and the path they travel across the sky. The Surya Siddhanta also provides information about the relationship of various stars, planets, and zodiacal signs. In this sense, the Surya Siddhanta is a complex and comprehensive treatise on astronomical phenomena. The Surya Siddhanta contains a list of astronomical terms. In this list, the author defines the vernal equinox as the first day of the lunar month called Chaitra. The full moon falls on the 15th day of the lunar month called Purnimanta. The summer solstice falls on the 5th day of the lunar month called Sravana. The winter solstice falls on the 15th day of the lunar month called Agrahayana.