Why Are There '24' Hours In A Day?

The 24-hour day concept comes from the ancient Egyptians. They divided the day into 10 hours with devices like shadow clocks and then added one hour at each end (one for twilight and one at the end of the day). Later, a T-shaped bar was made by Egyptians, which was calibrated to divide the time between sunrise and sunset into 12 parts. The absence of sunlight made it difficult to divide the time at night. Its pretty interesting to learn how they managed to do this. The nighttime division of time was based on the observation of stars. In those ancient times, with no sophisticated technology to use, they instead chose 36 star groups (small constellations) called decans, which rose consecutively on the horizon as the earth rotated. Each decan rose before sunrise and marked the beginning of a 10-day period. A total of 36 decans thus led to 36*10=360 days of a year. From one twilight to another, 18 of these decans were visible. However, each twilight period had 3 of these decans assigned, leaving 12 for the period of complete darkness. Thus, the rise of each decan marked an hour, so we ended up with 12 hours in each night. Then, Hipparchus gave us the Equinoctial hours by proposing the division of a day into 24 equal hours.