The history of Indian astronomy begins with the Vedic period, Lagadha and composition of Vedanga Jyotisha (1400 BCE - 1200 BCE). Astronomical knowledge in India reached an early peak in the 5th century CE, with the Āryabhaṭīya. Its author, Aryabhata, mentions that when he turned 23 years of age, 3600 years had passed since the beginning of Kali Yuga. This date has become traditional and is still widely cited in Hindu literature to suggest the date of Kurukshetra War.

Modern authors attempted to date the Vedic period based on archaeoastronomical calculations. In the 18th century William Jones tried to show, based on information gathered from Varaha Mihira, that Parashara muni lived at 1181 BCE.Bryant 2001:251 Hermann Jacobi has argued that in the Rigveda and Atharvaveda the sun was in Phalguni, and in the Sankhayana and Gobhila Grhyasutra the Full moon was in Bhadrapada during the summer solstice, which would have occurred at 4500-2500 BCE.Bryant 2001:254; Jacobi 1909

Jacobi and Tilak have both argued that the names of the nakṣatras: Mūla (root), Viśṛtau (two dividers) and Jyeṣṭha (oldest) suggest that these names originated from a time when Mula marked the beginning of the year, i.e. about 4500-2500 BCE.Bryant 2001:255 Tilak has also noted that the two week long pitrs period after the full moon in Bhadrapada occurred at the beginning of the pitryana, which would have been true at about 4500-2500 BCE.

Samhitas In RV 5.40.5-9, a solar eclipse is referred to: Surya is obscured by an Asura called Svarbhanu ("self-luminous"), but recovered by the Atris.

The samvatsara "full year" in the Yajurveda has 360 days, and 12 (TS) or 13 (VS) months.Bryant 2001:253

Brahmanas

The visuvant (summer solstice) period is 21 days in Aitreya Br. and 7 days in Pancavimsa Br., the summer solstice being in the middle of the period.Kak, Subhash: Archaeoastronomy and Literature, Current Science, vol. 73, no.7, 1997

The gavam ayana ritual in SB 4.6.2. is based on the motion of the sun.

In the Maitrayana Brahmana Upanishad (6.14), the year is said to be into two portions, with the part from Magha to half of Śraviṣṭha associated with Agni, and the part from Sārpa to half of Śraviṣṭha associated with Varuna and Saumya (the moon). Aiyar has arguedparaphrased and cited by Bryant 2001:257-8 that Agni suggests the warm half and similarly Varuna the cool half of the year, suggesting the summer solstice at the beginning of Maghā and thus implying the vernal equinox in Kṛttikā. This, according to Kak, would correspond to 1660 BCE.Subhash Kak. Birth and Early Development of Indian Astronomy. In Astronomy across cultures: The History of Non-Western Astronomy, Helaine Selin (ed), Kluwer, 2000

The Shatapatha Brahmana mentions that the Krttikas (the Pleiades) "do not swerve from the east".ŚBM 2.1.2.1: "One should found one's fires under the Krttikas ... These do not swerve from the eastern direction...All other Nakshatras deviate from the Eastern direction."The SB reference was first noted by Sankar B. Dikshit (Bryant 2001:256). Dikshit, Sankar B. 1985. "The Age of the Satapatha Brahmana" Indian Antiquary 24:245-6 This would have been the case with precision at 2950 BCE and was true also about 2000 BCE,(or during the third millennium BCE) e.g., Kak, Subhash: Archaeoastronomy and Literature, Current Science, vol. 73, no.7, 1997 but was still true to within 8-13 degrees (viz., East by north) around the 8th to 6th centuries BCE, the assumed date of the text's composition.

Vedanga Jyotisa

The positions of the solstices and equinoxes in the Vedanga Jyotisha, with the sun very close to the Krittika at the Vernal Equinox., would correspond to about 1370 BCE,Sastry 1985Bryant 2001:259. Keith 1912 although the text in its present form is from a later date, around 700 - 600 BCE.

The Vedanga Jyotisha, in common with Mesopotamian texts, asserts a 3:2 ratio between the durations of daylight on the longest and shortest days of the year. This corresponds to a latitude of about 35 degrees.Pingree(1978) A latitude of 34 degrees would correspond to Northern India.Bryant 2001:261. Yukio Ohashi 1997

See also Hindu astrology Indian astronomy Hindu Time Cycles

References

Literature

David Frawley. 1991. Gods, Sages, and Kings, Lotus Press, Twin Lakes, Wisconsin Kak, Subhash, The Astronomical Code of the Rigveda (1994, 2000). Tilak, Bal Gangadhar. The Orion, or, Researches into the antiquities of the Vedas, The Arctic Home in the Vedas, Vedic Chronology and Vedanga Jyotisha. Poona: Messrs Tilak Bros.