Ancient Astronomy


  Archaeoastronomy is best defined as the study of beliefs and practices concerning the sky in the past, and especially in prehistory, and the uses to which people’s knowledge of the skies were put. It can be misleading to think of archaeoastronomy as the study of ancient astronomy, since people in the past might have […]

Antizenith Passage of the Sun

  Just as the sun passes through the zenith, that is, directly overhead, twice a year as viewed from any location within the tropics, so it also passes twice a year through the point directly beneath the observer. This point is known as the antizenith or nadir. The dates of solar antizenith passage occur six […]


  Situated in Wiltshire, England, a few kilometers south of the modern town of Swindon, Avebury is one of the largest and most impressive Later Neolithic henge monuments in Britain. Built around the middle of the third millennium b.c.e., it measures some 350 meters (1,150 feet) across and surrounds an entire modern village. The outer […]

Astronomical Dating

  Is it possible to date an archaeological site by astronomical means? In theory, the answer is yes, for if we can identify an alignment and the intended astronomical target, measure where the alignment points, and then use modern astronomy to calculate where that event occurred at different times in the past, then we can […]


  To a modern astronomer, astrology is anathema. The idea that there can be any direct connection between the configuration or appearance of distant heavenly bodies in the sky and current or future events in the terrestrial world flies in the face of laws of physics that have been established beyond question over many centuries. […]

Babylonian Astronomy and Astrology

    Ancient Babylonia occupies a pivotal place in the history of modern scientific astronomy. In great part this is due to the conscientious nature of the astronomical observations that were made there and the meticulous way in which they were recorded for generation after generation. In time, the existence of a huge, cumulative database […]

Aztec Sacred Geography

  The Aztec (also known as the Nahua, or Mexica) empire—the last of the great Mesoamerican civilizations—dominated the highlands of central Mexico at the time of the arrival of Hernando Cortes in 1519. It had risen to power following a series of military conquests just a century or two earlier and maintained economic control by […]


  Azimuth means the bearing of a direction—such as that toward a particular point on the horizon from a given place—measured clockwise around from due north. Thus the azimuth of due north is 0°, that of due east is 90°, that of due south 180°, and that of due west 270°. The azimuth of a […]

Axial Stone Circles

  Axial stone circles (ASCs), or more correctly axial-stone circles, are a distinctive type of stone circle found only in the southwestern corner of Ireland, in counties Cork and Kerry. Only one other regional group of stone circles bears any resemblance to the axial stone circles: the recumbent stone circles (RSCs) found several hundred kilometers […]


  The very name of this large stone circle in County Donegal, northwest Ireland, is of astronomical interest because it suggests an association with the Celtic calendrical festival of Beltaine, or Bealltaine, which is associated with the mid-quarter day of May 6. A conspicuous alignment at the site backs up the idea of such an […]