Why do we use 60 seconds

During the New Kingdom to B. The clepsydra, or water clock, was also used to record time during the night, and was perhaps the most accurate timekeeping device of the ancient world.

The timepiece--a specimen of which, found at the Temple of Ammon in Karnak, dated back to B. Once both the light and dark hours were divided into 12 parts, the concept of a hour day was in place. The concept of fixed-length hours, however, did not originate until the Hellenistic period, when Greek astronomers began using such a system for their theoretical calculations.

Hipparchus, whose work primarily took place between and B. Despite this suggestion, laypeople continued to use seasonally varying hours for many centuries.

Hours of fixed length became commonplace only after mechanical clocks first appeared in Europe during the 14th century. Hipparchus and other Greek astronomers employed astronomical techniques that were previously developed by the Babylonians, who resided in Mesopotamia.

The Babylonians made astronomical calculations in the sexagesimal base 60 system they inherited from the Sumerians, who developed it around B. Although it is unknown why 60 was chosen, it is notably convenient for expressing fractions, since 60 is the smallest number divisible by the first six counting numbers as well as by 10, 12, 15, 20 and Although it is no longer used for general computation, the sexagesimal system is still used to measure angles, geographic coordinates and time.

In fact, both the circular face of a clock and the sphere of a globe owe their divisions to a 4,year-old numeric system of the Babylonians. The Greek astronomer Eratosthenes who lived circa to B. A century later, Hipparchus normalized the lines of latitude, making them parallel and obedient to the earth's geometry.

He also devised a system of longitude lines that encompassed degrees and that ran north to south, from pole to pole. In his treatise Almagest circa A. Each degree was divided into 60 parts, each of which was again subdivided into 60 smaller parts. The first division, partes minutae primae, or first minute, became known simply as the "minute.

Minutes and seconds, however, were not used for everyday timekeeping until many centuries after the Almagest. Clock displays divided the hour into halves, thirds, quarters and sometimes even 12 parts, but never by In fact, the hour was not commonly understood to be the duration of 60 minutes. It was not practical for the general public to consider minutes until the first mechanical clocks that displayed minutes appeared near the end of the 16th century.

Lots of civilizations borrowed from this number system, including the ancient Egyptians. That's why we now divide circles into parts, or degrees: 60 goes into six times. Did you know you can cut a circle into six triangles too?

It's also why people eventually decided to break up the face of a clock , which is also a circle, into 60 minutes … and then to break down each minute into 60 seconds. It took a long time before this happened. So next time you try to measure a minute by counting to 60, remember that people who lived thousands of years ago counted to 60 too! For further fun reading, check out Scientific American's article on how and why we measure the day.

There are a couple of theories as to why they chose Babylonian astronomers began cataloging stars in the 14th century B. Astronomy flourished as they developed a deep understanding of sun and moon cycles, and even predicted eclipses. Babylonian star catalogs served as the basis of astronomy for more than a thousand years despite the boom and bust of the Middle Assyrian Empire, the Neo-Assyrian Empire, the Neo-Babylonian Empire and the Achaemenid Empire. The conquests of Alexander the Great between and B.

Though the Greeks had their own numerals in base 10, Babylonian star catalogs created such a strong association between astronomy and the sexigesimal system that Greek and later Roman scholars kept using it. This association soon bled into navigation and trigonometry. Following the discovery by Eratosthenes of Cyrene that the Earth is round, in the first century B. Two centuries later in the Roman Empire, Ptolemy of Alexandria subdivided degree coordinates into 60ths minutes and 60ths of 60ths seconds.

Much of this knowledge was lost to Europe for several centuries after the fall of Rome in the fifth century A. The Islamic-Arabian empires inherited many Roman and later Indian ideas starting with the Rashidun Caliphate in the seventh century. Muslims scholars, after expanding on this knowledge greatly, reintroduced it to Europe in the eighth century through the Iberian Peninsula, which was then part of the Umayyad Caliphate.