Astronomy

Most ancient civilizations studied the skies for astronomical knowledge. Ancient astronomy has been studied by archaeologists in prehistoric Europe through monuments and in Central America through inscriptions and documents. Studies of prehistoric astronomy in Europe have concentrated on the megalithic monuments and stone circles, which have been proven to incorporate alignments of the sun, moon, and brighter stars - especially significant points in their cycles. Solar alignments occur at New Grange and Stonehenge, lunar orientations at the Recumbent Stone Circles of Aberdeenshire and the Carnac stones in Brittany. Many theories are discussed as to the accuracy of measurements and the degree of astronomical understanding achieved by these early societies. The ability to predict astronomical events would have enhanced political power, which is something suggested in Mesoamerica. The ability to predict events by the governing elite class increased their credibility as able rulers. The Mesoamerican people put great emphasis on the calendar and astronomy and were able to make extremely accurate measurements of the solar year, the appearance of eclipses, and the phases of the Moon. Buildings seen as observatories occur at Chichen Itza and at Palenque, and the Dresden codex is a detailed collection of calculations tracing the eclipses of the Moon and Sun and the cycles of Venus and possibly Mars and Jupiter. The Maya were even aware of the impreciseness of the 365-day year in their Calendar Round and added a correction factor to account for the quarter-day per year discrepancy. The cycle of the Moon, in comparison, was calculated with amazing accuracy (29.5302 days compared to the actual figure of 29.5306). The cycle of Venus (calculated at 583.92) was also pinpointed as accurately as measurements taken by modern astronomical methods. The ancient astronomers' awareness of long-term astronomical phenomena was astonishing.

Most of the ancient civilizations of the world studied the skies and some achieved considerable astronomical knowledge. In the main, ancient astronomy is known from documentary sources rather than material evidence and so falls within the realm of history rather than archaeology. In two cases, however, ancient astronomy has been studied by archaeologists: in prehistoric Europe, where the evidence comes entirely from the monuments themselves, and in central America, where the evidence comes largely from inscriptions and documents, but where there is no separate discipline concerned with the literature (in contrast to Egypt or Mesopotamia, for example). Prehistoric Europe. Studies of prehistoric astronomy have concentrated on the megalithic monuments of northwest Europe and especially the stone circles of the British Isles and the alignments of Brittany, dating to the Late Neolithic and Early Bronze Age. Research by Alexander Thom and others has shown that many of these monuments incorporate alignments on the rising and setting of the sun, the moon and some of the brighter stars, at various significant points in their respective cycles. Solar alignments are present at the famous sites of New Grange and Stonehenge, as well as many others, while a lunar orientation characterizes the recumbent stone circles of Aberdeenshire as well as the Carnac alignments in Brittany. Although most scholars now accept that many monuments reflect a concern with celestial events on the part of the societies that built them, there is considerable disagreement about the accuracy of measurement and the degree of astronomical understanding achieved. Whereas modem astronomers and other scientists have tended to emphasize the accuracy of the prehistoric alignments and to regard the monuments as true observatories, prehistorians have been more sceptical. It may well be that the monuments were temples where astronomical knowledge was exploited by an elite priesthood to produce spectacular theatrical effects such as the lighting-up of the chamber at New Grange at midwinter sunrise, the rising of the midsummer sun behind the Heel Stone at Stonehenge, or the floating of the moon along the top of the recumbent stone in the Scottish recumbent stone circles. The ability to predict astronomical events and produce spectacular effects would certainly enhance political power — a function which is also suggested for the astronomical achievements of Mesoamerica. Americas. It has long been known that the calendar system of Mesoamerican groups (notably the Maya and the Aztec) was based on the cyclical nature of the movement of heavenly bodies. Buildings seen as observatories occur at Chichen Itza and at Pal-enque, and the Dresden Codex is a detailed collection of calculations tracing the eclipses of the moon and the sun and the cycles of Venus and possibly Mars and Jupiter. Although the solar year incorporated in the Calendar Round was an imprecise 365 days long, the Maya were aware of the error and ultimately initiated a correction factor to account for the quarter day per year discrepancy (see secondary series). The cycle of the moon, in comparison, was calculated with astonishing accuracy (29.5302 days compared to the actual figure of 29.5306). Beyond this, the cycle of Venus (calculated at 583.92) was also pinpointed to a degree of accuracy comparable to measurements taken by modem astronomical methods. Perhaps most spectacular of all is the awareness of long-term astronomical phenomena. Both the central Mexicans and the Maya knew that five Venus cycles were equal to eight earth cycles, but most remarkable was the combination of the periods of Venus, the earth and the Calendar Round into a cycle 104 years long. Astronomical calculations were long regarded as a curious (although probably religious) obsession with the passage of time; they are now believed to have had a notably secular and practical element to them, namely the use of the ability to predict astronomical events as an instrument of political control. Concentrated in the hands of the governing elite class, the apparent ability to predict events in the heavens would certainly have increased the credibility of the elite as able rulers.