The first calculations of the age o

The first calculations of the age of the calendar were made based on the rise of Orion, a constellation known for its three bright stars forming the "belt" of the mythical hunter. The Earth wobbles on its axis, so the stars and constellations change their angle of presentation in the night sky on a cyclical basis. This rotation, called the precession completes a cycle about every 26,000 years. By determining when the three stars of Orion's belt were positioned flat (horizontal) against the horizon, it is possible to estimate the time when the three stones in the calendar were in alignment with these stars. According to Tellinger, a calculation done by astronomer Bill Hollenbach based on the rise of Orion suggested an age of the site of at least 75,000 years. A further calculation done in June 2009, suggested an age of at least 160,000 years, based on the rise of Orion 'flat on the horizon' but also on the 'erosion of dolerite stones' found at the site. Some pieces of the marker stones had been broken off and sat on the ground, exposed to natural erosion. When the pieces were put back together about 3 cm of stone had already been worn away. These calculation helped assess the age of the site by calculating the erosion rate of the dolerite.