The JPL ephemeris, and the software using them, are in any case sufficiently reliable at least till 3000 BCE for the position of the Sun and till the 1500 BCE for the position of the Moon and the planets. These software have almost the same accuracy of the JPL ephemeris: they could thus be considered entirely reliable since the 7th century BCE, thanks to the calibration on the Babylonian astronomical compendia, losing their precision going back in time. The problem of the former is that, being developed for the control of a telescope to date, they roughly correct the effects of the precession of the equinoxes and the other time-dependent astronomical effects are usually not taken into account.įrom the 1990s, a number of astronomical software specialists used the same system to solve the problem: consider the NASA JPL ephemeris as data source, calculated by a super-computer and calibrated on the historical observations of the solar and lunar eclipse, then compute by interpolation the position of the astronomical objects and the aspect of the celestial vault at the desired date. The first archaeoastronomical studies employed commercial virtual planetarium software (such as “Starry Sky”) or specific software developed by several authors (such as “Stonehenge” of Gerald Stanley Hawkins). For this task it is necessary the use of planetarium software, capable of calculating the precession of the equinoxes and the other effects that modify the position of the celestial bodies in the sky. After recognizing these orientations, it was essential to compare them with a reconstruction of the sky at the time in which the astronomically oriented monument was built. During the last decades, Archaeoastronomy has also witnessed significant development in Italy, due to the efforts of the Italian Archaeoastronomical Society ( SIA), started in 2000 under the auspices of the Accademia Nazionale dei Lincei that in the 1990s organized three important conferences, playing a role similar to the one of the Royal Society.Īrchaeoastronomical studies soon discovered that ancient builders gave to astronomical orientations a calendrical meaning, indicating an astronomical event important for the religious life of a community.
Currently, major international (such as SEAC and ISAAC) and national scientific societies are devoted to Archaeoastronomy in past and present cultures. The Conferences are still today attended by humanities scholars, scientists and astronomers. An important role in the recovery of archaeoastronomical methods was played by the Royal Society, which in 1981 promoted the first Oxford International Conference on Archaeoastronomy, where the study of astronomical orientations of archaeological sites was one of the topics discussed. However, due to a large number of archaeoastronomical works conducted in the 1960s without taking into account the actual archaeological and historical contexts, Archaeoastronomy began to be perceived with suspicion and was then utterly rejected by a large number of archaeologists. These studies gave rise to many important research projects, concerning European prehistoric sites as well as important Egyptian, Mesopotamian and pre-Columbian monuments and sites, so that, in the middle of 20th century, it was widely agreed that astronomical orientation was an important component of the architectural solutions chosen by many cultures. Other scholars produced significant results by applying Lockyer’s methods. His studies on Egyptian pyramids and Stonehenge became a model of subsequent archaeoastronomical studies, while his book Surveying for Archaeologists (1909) established the basic principles for that part of Archaeoastronomy devoted to the detection of astronomical alignments. The archaeologist Sir William Matthew Flinders Petrie was the first to quantitatively study, in 1880, the famous megalithic monument of Stonehenge, by checking the presence of an astronomical alignment with the summer solstice sunrise.įourteen years later the astrophysicist Sir Norman Lockyer returned to the idea of astronomical orientations in ancient buildings. The first studies designed to recognize the role of celestial phenomena in ancient civilizations were conducted with coherent and partially codified methods in the United Kingdom between the end of the 19th and the beginning of the 20th century and focused on the possible astronomical meaning of a number of archaeological sites in the British Islands. Archaeoastronomy is a subsidiary science to Archaeology aiming at identifying astronomical connections of structures and artefacts of archaeological interest.
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