Buzz
A day is the time it takes for Earth to complete a full rotation. But how did people determine the length of an hour, minute, and second? The ancient Egyptians were the first to divide a day into smaller sections over 3000 years ago, using sundials, the earliest form of clocks. Have you ever noticed how your shadow changes size depending on the time of day? The Egyptians tracked time by placing stakes in the ground and measuring the shadows they cast.
Sundials gradually became more elaborate. One type, shaped like the letter “T,” divided the daylight hours into 12 parts. While the reason for choosing 12 is unclear, some believe it was because 12 is divisible by two, three, four, and six. In contrast, although ten is easy to count due to our ten fingers and toes, it can only be divided by two and five.
However, sundials were ineffective after sunset. To measure time during the night, the Egyptians turned to the stars. Just as the Sun moves across the sky, the stars shift too. By observing the position of certain stars, they could determine the time of night. They tracked 12 stars to help measure the time when it was completely dark. Combine the 12 hours of darkness with the 12 hours of daylight, and you get 24 hours in total.
The ancient Babylonians had a preference for the number 60, a system that many other cultures, including the Egyptians, adopted. This is why we divide circles into 360 degrees: 60 divides evenly into 360, six times. (Did you know a circle can also be divided into six triangles?) This system is why clocks are divided into 60 minutes, and each minute contains 60 seconds. It took centuries for this to become the standard. So, next time you measure a minute by counting to 60, remember that ancient civilizations did the same thing!
For more exciting reading, explore Scientific American's article on the reasons behind how and why we measure the day.
