Ancient astronomical observatories

FUTURE OF THE PAST: ICTS Mini Workshop, Mangalore, 22-26, 2011 Ancient astronomical observatories Srikumar M. Menon Manipal University, Manipal Stonehenge Nilaskal

The Fascinating Heavens the sky as a cultural resource

The Fascinating Heavens the sky as a cultural resource Scorpio? Supernova? Petroglyph discovered in White Tank Regional Park, Arizona

The Fascinating Heavens the sky as a cultural resource The supernova of 1006AD

Prehistoric Astronomy: evidence for observing instruments? Hanamsagar* Mayan Zenith Tubes** Harappan Gnomons?* Brahmagiri # # Rao, N. K., Bull. Astr. Soc. India (1993) 21, 67-77. *Rao, N. K., Bull. Astr. Soc. India (2005) 33, 499-511. **Aveni, A., Tropical Astronomy, Science (1981)

A bit of Positional Astronomy The Celestial Sphere

A bit of Positional Astronomy Co-ordinate Systems

A bit of Positional Astronomy Declination (0 o to 90 o N & S) Right Ascension (0 h to 24 h ), measured from vernal or spring equinox

The Cycle of the Sun

The Cycle of the Sun The Solstice

The Cycle of the Sun The Solar Cycle (for a location N of the Equator)

Against a convenient skyline...

Stone Markers? Saptarshi rise point locator N W Variation of Sunrise points during different months E Constellation locators S Courtesy: Prof. Mayank Vahia, TIFR

The Cycle of the Moon The Lunar Cycle

The Cycle of the Moon 18.6years 18.6years Horizon Horizon Monthly swing (Minor Standstill) Monthly Swing (Major Standstill)

Lunar Alignments and Sightlines N Major standstill northern moonrise Minor standstill northern moonrise Minor standstill southern moonrise Major standstill southern moonrise Major standstill northern moonset Minor standstill northern moonset Minor standstill southern moonset Major standstill southern moonset

Celestial Alignments and Sightlines

Precession of the Equinoxes Precession is due to a gyroscopic wobble of earth's spin axis that takes 26,000 years to complete. In this wobble motion, the tilt of the earth stays roughly constant at 23.4 degrees but the orientation is always changing. Precession

Precession of the Equinoxes The north star Polaris is drifting. It is only "north star" by coincidence today. Vega will be our north star for a time in the distant future. Since the point where the projection of the rotation axis of the Earth strikes the Celestial Sphere moves around, this means that the North Celestial Pole moves around in a circle among the stars. This produces changes in the coordinates of stars. Today, it is fortuitous that the North star is Polaris. At other times, other stars were or will be the North star! Precession

Precession of the Equinoxes Precession

Precession - what it implies for us Due to Precession, the position of Equinox Sunrise and Sunset, Solstice Sunrise and Sunset etc. will be different for different eras. So one has to account for Precession while assessing monuments for alignments with these phenomena Amount of Precession: * # One complete cycle = 25,800 years Equinoxes move Westward by ~ 50.3 per year Which is 1 o every 71.6 years *Narlikar, J. V., The Scientific Edge: The Indian Scientist from Vedic to Modern Times (2003) Penguin Books, pp 7 # Ridpath, I. (ed.), Norton s Star Atlas and Reference Handbook (Epoch 2000.0) (1998) Addison Wesley Longman Ltd., Pp 43

Archaeoastronomy and Related Fields The study of astronomical practices, celestial lore, mythologies, religions and world-views of all ancient cultures is called ARCHAEOASTRONOMY. Archaeoastronomy, in essence, is the anthropology of astronomy. The study of the practice of astronomy using both the written and unwritten records. It began as a meeting ground for three established disciplines: (Aveni, A., Journal of Archaeological Research, Vol.11, No.2, 2003) Astroarchaeology a methodology for retrieving astronomical information from the study of alignments associated with ancient architecture. (Hawkins 1966) Ethnoastronomy a branch of cultural anthropology that develops an understanding of cultural behavior as gleaned from indigenous perceptions of events in the heaven. (Fabian, 2001)

The Stonehenge Controversy Stonehenge an exceptional monument..?

The Stonehenge Controversy Decades of research by several workers

The Stonehenge Controversy A composite structure (~3500 BC 1500 BC)

The Stonehenge Controversy Too many celestial alignments..?

The Stonehenge Controversy An eclipse predictor too..?

Alexander Thom and his Work long, patient, accurate and modestly pursued work on a large number of sites.

Alexander Thom and his Work Accurate surveys of a large number of sites

Alexander Thom and his Work Mainly alignments in megalithic sites; but also on their design (geometry).

The importance of measuring Orientations for a large number of sites

The BIG Question Is an inferred sightline actually intentional or a chance alignment?

Megalithic Calendar Devices..? Stone alignments and Avenues prime candidates Topography to be taken into account too while considering sightlines Carnac Horizon visibility from each backsight to be considered too Callanish

Teotihuacan Astronomical Town Planning..?* *Krupp, E. C., In Search of Ancient Astronomies (1977) Doubleday, New York.

Teotihuacan Astronomical Town Planning..?

Chankillo: The Mystery of the Thirteen Towers

Chankillo: The Mystery of the Thirteen Towers *The thirteen towers situated on a N-S ridge within a 4 th Century BC ceremonial complex. Most prominent feature the citadel (a fortified temple?) The towers vary in area (75 125 m 2 and in height (2-6m) Regularly spaced gap between adjacent towers vary from 4.7m 5.1m A structure on the West 235m away with a corridor to a door-less opening facing towers A small, isolated building on Eastern side almost mirror-image of W observing position in distance and elevation *Ghezzi, I. and Ruggles, C., Chankillo: A 2300-Year-Old Solar Observatory in Coastal Peru, Science (2007) Vol. 315

Chankillo: The Mystery of the Thirteen Towers

Chankillo: The Mystery of the Thirteen Towers Sunrise at the 13 towers

Chankillo: The Mystery of the Thirteen Towers Sunset at the 13 towers

Dholavira: the structure in the bailey

Dholavira: the structure in the bailey Play Video!!

Whose point of view..? Sepulchral BRW Stratigraphy Form Space Order! Equinox, solstice Alignments Every age has the Stonehenge it deserves or desires. Jacquetta Hawkes, 1967

The REAL thing!

FUTURE OF THE PAST: ICTS Mini Workshop, Mangalore, 22-26, 2011 Thank You! Nilaskal