Steven R. Gullberg, Ph.D. Director for Archaeoastronomy and Astronomy in Culture School of Integrative and Cultural Studies College of Professional and Continuing Studies University of Oklahoma, Norman, Oklahoma, USA Chair, International Astronomical Union Working Group for Archaeoastronomy and Astronomy in Culture [email protected] International Astronomical Union (IAU) Archaeoastronomy Inca Astronomy Milky Way Chaco Canyon Babylonian Astronomical Diaries Education for Astronomy in Culture International Astronomical Union International Astronomical Union International Astronomical Union International Astronomical Union International Astronomical Union The sky is a resource largely unchanged since antiquity ASTRONOMY ARCHAEOLOGY Measurement and Inferring ancient testing of culture from observable sky material evidence events We can use astronomy as a tool to gain further insight into ancient cultures Archaeoastronomy deals with the astronomical significance of sites and structures of prehistoric peoples. Archaeoastronomical studies are interdisciplinary in that they incorporate astronomy, archaeology, and anthropology. They often involve investigating possible astronomical alignments and their cultural associations. Ethnoastronomy deals with the astronomical systems of indigenous peoples. Ethnoastronomical studies combine anthropology and astronomy, but sometimes also incorporate data drawn from prehistory, geology, linguistics, and genetics. Seek understanding of culture using astronomy as a tool A discipline that can assist archaeology/anthropology Assess and validate previously published cultural astronomy work Test building astronomical associations with: Directional orientations Solar events such as solstices and equinoxes Lunar events Conduct field surveys Sighting Compass Theodolite GPS Analyze and validate astronomy predictions U.S. Naval Observatory data Photo-confirmation of predicted astronomical events Interpretation–Focus on the people; assess results in cultural context It is important that findings are supported astronomically. Movement of astral bodies on the celestial sphere is defined mathematically and can be precisely calculated with spherical trigonometry, long a mainstay of archaeoastronomical research. If a spherical triangle is defined as having three angles labeled A, B and C, and the sides opposite those angles are correspondingly labeled a, b and c, then the following are the basic formula for solving spherical triangles. cos a = cos b cos c + sin b sin c cos A (1) sin A/sin a = sin B/sin b = sin C/sin c (2) sin a cos B = cos b sin c – sin b cos c cos A (3) cos a cos C = sin a cot b – sin C cot B (4) These may be used in archaeoastronomy to calculate angles and distance that specify horizon points of celestial bodies and verify field data taken by sighting compass, GPS, and theodolite. Hour angle of the Sun in degrees = (GMT-12)15 – LONG – (EOT)15 (5) Altitude of the Sun = Arcsin(Sin(LAT)Sin(DEC)+Cos(LAT)Cos(DEC)Cos HA)) (6) Azimuth of the Sun = Arcsin (Sin(HA)Cos(DEC)/Cos(ALT)) (7) Where HA = Hour Angle, GMT = Universal Time Coordinated, LONG = Longitude, EOT = Equation of Time, LAT = Latitude, DEC = Declination, and ALT = Inclination. In horizon astronomy research, when the angular altitude of the horizon at or above level is known by measurement with such as an inclinometer, the latitude of the site in question is taken from a chart or GPS measurement, and the declination of the Sun is derived from the nautical almanac, the following formula is most useful for calculating the position on the horizon that the Sun will rise. Azimuth of Sun = Arccos ((Sin(DEC) – sin(LAT)Sin(ALT))/(Cos(LAT)Cos(ALT)) (8) Precession of the Equinoxes Slow wobble of Earth’s axis over nearly 26,000 years Celestial poles and celestial equator migrate Right ascension and declination change over time as a result and the difference in declination leads to new rising and setting azimuths for stellar objects. Not a factor within solar system Obliquity of the Ecliptic Inclination of the Earth’s equator to the plane of the ecliptic is presently 23.439° Decreases at a rate of about 47 arcseconds (0.013°) every 100 years A consideration for celestial measurements regarding ancient structures Refraction Celestial bodies appear higher in the sky than they actually are Result of light being slightly deflected due to differences in atmospheric density and has a greater effect near the horizon Azimuth is shifted due to refraction - more pronounced at higher latitudes with smaller incident angles to the horizon than in the tropics Becomes negligible at inclinations 20° or more above the horizon Pronounced at higher latitudes and generally insignificant in the tropics Atmospheric Extinction Absorption and scattering of photons when colliding with particles or air molecules Atmospheric water, carbon dioxide and oxygen are primary absorbers Rayleigh Scattering occurs with air molecules smaller than the wavelength of the photons Mie Scattering results with photons striking small atmospheric particles of similar wavelengths Extinction not an issue with the Sun and Moon, but becomes significant when observing faint stars near the horizon, such as the Pleiades Horizon Deviation Occurs when the visible horizon differs from the astronomical horizon Commonly in areas of mountainous terrain and is most pronounced at higher latitudes where the arc of travel for a specific body can yield a significantly different point for rising or setting than that given for the astronomical horizon. Horizon Deviation Altitude above astronomical horizon Latitude 13.5° Latitude 40° 1° 0.22° 1.04° 2° 0.49° 1.99° 4° 1.07° 3.84° 6° 1.69° 5.63° 8° 2.35° 7.37° 10° 3.04° 8.06° Precession is not a concern for solar observations, but for measurements involving stars such as the Pleiades it must be taken into consideration Obliquity of the ecliptic has changed 0.0649° since the time of the Incas, resulting in a difference in azimuth of 4’ at a latitude of 13° and is therefore negligible Refraction and extinction can be important when examining the rising and setting of stars, they are not a concern for the Sun. The rising and setting of all celestial bodies at the S13.5° latitude in Cusco, the Sacred Valley, and Machu Picchu must take horizon deviation into account. Astronomy was an integral part of Andean mythology and creation, and was at the very heart of the Incas’ religion and agriculture. The Incas proclaimed themselves to be the children of the Sun. They worshipped it and viewed their emperor as being the Sun’s direct descendant. The Emperor, Pachacuti, his son, and grandson successively built the largest empire ever known in the Americas, 4800 km from Chile to Columbia. Temples and shrines were constructed as a part of exerting state control over its subjects, as well as pilgrimage centers designed to reinforce the legitimacy of royal rule over the populace. The Incas made solar worship the official religion of their empire. Pachacuti imposed it across the realm, maintaining that he was the son of the Sun and his wife the daughter of the Moon. The Incas venerated the Sun, the Inca, and his predecessors. The ruling Inca was the central figure in solar worship, supporting the assertion that he was the descendant of the Sun. The Incas learned the cycles of solstices and equinoxes and used this knowledge as a key component of their annual crop management activities, as well as for determining dates for religious celebrations. ● Limestone outcropping ● Carved in situ ● Two sucancas (gnomons) ● Effects of light and shadow ● June solstice sunrise ● “The Awakening of the Puma” ● Cave within Kenko Grande ● Altar and three stairs ● June solstice ● Sunlight climbs the stairs ●Light-tube ●Directed at altar ●Crescent moon Lacco with Nevado Ausengate ● Northeast Cave opening oriented June solstice sunrise ● Illuminates altar and cave interior ● Temple of the Sun ● Light-tube/Altar ● Zenith Sun ● Limestone outcropping ● Two carved circles ● Carved seats ● Alignments for solstice and equinox horizon events June Solstice Sunrise ● Terraces and fountains ● Intihuatana ● Elite/non-elite viewing of the June solstice sunset In Saihuite the axis between the horizon points of the June solstice sunrise and December solstice sunset dominates the upper sector of the complex. The Principal Stone lies with the adjacent structure on the axis of the June solstice sunrise and December solstice sunset. Niche and corridor aligned for the June solstice sunrise. Niche and corridor aligned for the June solstice sunrise. Intihuatanas, or “hitching places of the sun,” are also found at Machu Picchu, the Urubamba River, and Tipon and likely were places of solar worship. In Pisac the intihuatana is a large, partially carved rock in the temple group that is enclosed by a semi-circular masonry wall adjoining a straight masonry wall in the form of the letter “D”. It displays a stone gnomon on its flat upper surface within the walled enclosure. The gnomon aligns with a nearby peak in the 065° direction of the June solstice sunrise. The Intihuatana of Pisac ● Sixteen towers once on Cusco horizon ● Beyond Cusco 2 survive near Urubamba on Cerro Saywa ● Mark rising Sun at June solstice when viewed from palace of Huayna Capac ● Validate chronicles of Cusco pillars ● DSSR view from white granite boulder at Q’espiwanka ● View across Cerro Pumahuachana ● Pillars on 4377m summit ● North/South alignment The orientation of Cerro Unoraqui as viewed across Cerro Pumahuachana from Q’espiwanka in the direction