Great History Challenge Practice Test

Dividing the circle into 360 degrees comes from ancient Mesopotamian astronomy, where a sexagesimal (base-60) number system made 360 a convenient and highly divisible number for calculations. Babylonian scholars, often referred to as Chaldeans, tied this circle division to their observations of the Sun’s yearly path and the roughly 360-day year, so splitting the circle into 360 equal parts allowed easy work with angles and orbital measurements. They also organized the zodiac into twelve signs of 30 degrees each, which sums to 360, reinforcing the system that later became standard in Greek and Western astronomy. The other civilizations contributed to measurement and astronomy, but the specific 360-degree circle is best traced to the Chaldeans/Babylonians due to their mathematical framework and astronomical practice.