Many ancient civilizations observed astronomical bodies, often the Sun and Moon, to determine times, dates, and seasons. The history of calendars spans several thousand years. In many early civilizations, calendar systems were developed. For example, in Sumer, the birthplace of the modern sexagesimal timekeeping, now common in Western society, there were 12 months of 29 or 30 days apiece, much like the modern Gregorian calendar. A similar system was developed later in Mesoamerica.
The first calendars may have been created during the last glacial period, by hunter-gatherers who employed tools such as sticks and bones to track the phases of the moon or the seasons.
Stone circles, such as England’s Stonehenge, were built in various parts of the world, especially in Prehistoric Europe, and are thought to have been used to time and predict seasonal and annual events such as equinoxes or solstices. As those megalithic civilizations left no recorded history, little is known of their calendars or timekeeping methods.
The megalithic precincts at Göbekli Tepe, predating Stonehenge by 6,000 years, served different capacities over the near two millennia (or more) of their use. The circles were not coterminous, but were built successively over this extended period.
The enclosures excavated thus far are arranged in calendar-like circle structures made up of nearly 12 sculptured pillars, with two offset T-shape pillars dominating each circle at the centre. Their design suggests a reflection of the cosmos as if their builders had an interest in the movement of the sky, and there is evidence they did.
Based on the slightly drifting southwest trajectories of circles labeled Enclosures A, B, C, and D, Robert Schoch proposed the builders of Göbekli Tepe were aware of precession, or discovered its effect over an extended period – c10.000-8500 B.C. corresponding to when the Orion-Taurus-Pleiades constellations were visible before dawn on vernal equinoxes from the direction of the T-shape pillars at the centre of each enclosure.
Rather than this being architectural happenchance, pillar 43 of Enclosure D (the oldest circle at the site), known as the ‘vulture-stone’, further supports the view the circles were constructed to chart the movement of seasons. A fresco decorating the vulture-stone portrays what appears to reflect a geographical region of the sky. This is suggested powerfully by the central orb, or ball, poised on the vulture’s wing which appears to depict the sun.
Below the jubilant vulture is the figure of a scorpion, a snake, below which is a headless ithyphallic man to which the orb above may have belonged. The scenario is like the mutilated Osiris personifying the mysterious ebb and flow of the ancient Egyptian seasonal cycle; the god who germinated the world with renewing essence while remaining hidden in the beyond. Using StarryNightPro software, it can be determined that at Göbekli Tepe c10.000-9700.B.C. the summer solstice sun occupied the zodiacal house of Scorpio.