One Day On Two Orbits

The flat sculpture embedded in the ground renders homage to a man whose skepticism has led to an adjustment of the Ptolemy Almagest, the more than 1,200 years of unquestioned understanding that the Earth would be the center of the solar system. Although Alhazen kept the geocentric hypothesis, he eliminated the equant theory (assuming that the moon and the sun would be orbiting the Earth on similar tracks) and introduced the idea that the sun and the moon revolve in geometrically and temporally (speed) different orbits. This discovery finally led to a better understanding of both space and time on Earth and could explain the existence of two calendar systems, one of which relates to the solar orbit—the so-called occidental calendar—and the other, the oriental calendar, to the lunar orbit. In this regard, One Day on Two Orbits is meant to be a memorial for Alhazen’s discovery that not only relocated the Earth in the solar system; it also harmonized different cultures of time, bringing together the Orient and the Occident.