What is Surya Sidhdhant? How Bhaskaracharya was the first to discover gravity, 500 years before Sir Isaac Newton?
It is said that many years ago Bhaskaracharya discovered gravity using Surya Sidhdhant. What is that?
Surya Siddhanta is the ancient Indian Astronomical treatises which has a significant importance in Vedic astronomy.
It was used for knowing the positions of planets in the sky, calculation of eclipses, solstices, sidereal motion, and many other complex mathematical & trigonometric calculations.
It was also the main backbone for Indian calendar calculations. The panchAngam was largely based on these siddhantas. However, now a days Drik system is more commonly used in the panchAngas.
In a work called the Pañca-siddhāntikā composed in the sixth century by Varāhamihira, five astronomical treatises are named and summarised: Paulīśa-siddhānta, Romaka-siddhānta, Vasiṣṭha-siddhānta, Sūrya-siddhānta, and Paitāmaha-siddhānta. Judging from the epoch dates in the work, Plofker suggests that this Sūrya-siddhānta was composed or revised in the early sixth century
This book has 14 chapters. They arc:
Chapter 1 — Of the mean motion of planets, Preface, division of time, measurement of Yugas ( Yugamana), number of days, aharganas, revolutions, Mean of bhagana planets etc., conjunction and node of apsis for planets (Mandocca and sighra), Deshantara and inclination of their path to the ecliptic (parama vikshepa) .
Chapter 2 — Of the true places of the planets; Causes of planetary motion, types of motions, determination of sines (jya), declination and finding out the Kendra, determination of circumference from the base and perpendicular and their results of sine and cosine, corrected position of the planets, correction of bases, corrected motion, true latitude (vikshepa), length of day and night, Chara, Tithi, constellations (nakshrata), yoga, karana (portions and halves of lunar days).
Chapter 3 — Of direction place and time; Determining east-west meridian, part of solstice, equinoctial shadow, sine of co-latitude, zenith-distance, measure of amplitude, angle of the cone, Niraksha, point upon ecliptic (Lagna) and meridian ecliptic point (Dashama).
Chapter 4 — Of eclipses especially of lunar eclipse; corrected longitude of moon, measure of sun and the shadow (chdya), obscuration (Grasa), half-duration of the eclipse (Stithyardha), corrected perpendicular (Kotii), Valanarhsa (degrees of deflection).
Chapter 5 — Of parallax in solar eclipse; parallax in longitude of moon (Candra Lambana), parallax in latitude, solar eclipse (Suryagrahana).
Chapter 6 — Of the projection of eclipse; Parilekhadhikdra
Chapter 7 — Of planetary conjunctions; planetary conjunctions (Grahayutyadhikara), Akshadrikkarma, Ayanadrikkarma, disc of the planet (Grahavimba) viewing of the planets and encounter (Yudha)
Chapter 8 — Of the constellations; planet-constellation conjunction (Yutyadhikara), position of the constellations.
Chapter 9 — Of heliacal rising and setting; containing; rising and setting (Udaydstddhikdra), determination of time, portions of time (Kdldngsa).
Chapter 10 — Of moon’s rising and setting and elevation of her cusps; sringonnati.
Chapter 11 — Of certain malignant aspects of sun and moon; Patadhikara, Vyatipdta, Determination of time, Gandaka, Bhasandhi.
Chapter 12 — Of cosmogony, geography, dimensions of the creation;
Spiritual science, Kakshasthiti, Pole, Bhadrasva, Yamakotl Lanka, Ketumala, Polar star, Distance from the earth.
Chapter 13 — Of armillary sphere and other instruments.
Chapter 14 — Of the different modes of reckoning time.