The ancient Babylonians knew that the Earth revolves around the sun and that it takes about 360 days to make one complete revolution. Of course, we know that the required time is much closer to 365•1/4 days. In any case, one logical explanation for the choice of a base of 60 suggest that it resulted from their 360 day calendar. From this developed the idea that a circle consisted of 360°. This meant that the earth's movement along its orbit about the sun was of 1/360 of 360° or 1° each day. This notion could then have been coupled with their knowledge that the circumference of a circle can be divided into six equal arcs by marking