Buzz
Angles are a crucial concept in mathematics and physics. When representing angles, we often use degrees as the unit. However, why is the circumference of a circle 360 degrees instead of a simpler number like 100 or 200 degrees?
There are several perspectives on the origin of 360 degrees, among which two main viewpoints stand out.
1. Related to astronomy
In ancient times, humans used the Sun, the Moon, the stars, and other natural phenomena to measure time and create calendars. Among these, the position of the Sun was crucial for compiling solar calendars.
The Sumerians observed the Sun, the Moon, and the five visible planets (Mercury, Venus, Mars, Jupiter, and Saturn), primarily for divination purposes. They did not attempt to understand the physical motions. However, they noticed the circular path of the Sun's yearly journey across the sky and knew it took about 360 days to complete a yearly cycle. Therefore, they divided the circle into 360 degrees to track the Sun's entire journey each day. This likely occurred around 2400 BCE. This is the earliest origin of the 360-degree system.
2. Associated with base 60
In ancient times, humans often used fingers for counting, hence the base number was 10, known as the decimal system. Hindu-Arabic numerals are the most widely used symbols to represent numbers. They are considered one of the most significant achievements in mathematics and serve as a counting and computing system based on 10.
However, in ancient times, some civilizations used 60 as the base, known as the sexagesimal system (Base 60 counting system). The number 60 is one of the ancient counting methods of humans, originating from ancient Semitic people in the 3rd century BCE and later spread to Babylon and elsewhere.
The reason why 60 was used instead of other numbers may be because 60 is a relatively small number and can be divided into 10 real divisors: 2, 3, 4, 5, 6, 10, 12, 15, 20, and 30. This makes the sexagesimal counting system more flexible for various calculations.
Additionally, the use of the base 60 is also convenient for drawing with rulers and measuring tools. In the Eastern lunar calendar, there is a concept of the sexagesimal stem-branch, which is the combination of 6 celestial stems with 5 terrestrial branches to form a system of 60.
The sexagesimal counting method was then spread by the Arabs to Europe, eventually becoming the dominant method, widely used in time, angles, geographical coordinates, and other fields.
Around 300 to 100 BCE, the Babylonians divided hours into fractions of 60: 60 minutes in an hour and 60 seconds in a minute. Their base 60 system still exists in our angle and time divisions (1 hour = 60 minutes, 1 minute = 60 seconds, but 1 second = 1000 milliseconds - because milliseconds appear in modern times and the base 10 has become the predominant trend at this time).
Thus, using 360 degrees to represent angles is more convenient than 100, as it can be divided into various angles, all of which are integers, making calculations more convenient and reducing the likelihood of computational errors.
In conclusion, the origin of 360 degrees as an angle unit may stem from ancient civilizations, offering advantages and significance across history, culture, technology, and mathematics. Hence, it has become an indispensable part of modern science and engineering.
While the number 100 is simpler, it does not meet these requirements well, hence 360 degrees has become a widely used unit of angle measurement. Although other angle units (such as radians) have their unique application scenarios, 360 degrees, as a universal angle unit, has become the most common measure in scientific and engineering fields.
The number 100, although simpler, fails to fulfill these requirements adequately, thus 360 degrees has become the prevalent unit of angular measurement. Despite other angular units (such as radians) having their unique application scenarios, 360 degrees, serving as a universal angular unit, has become the most widely used measure in scientific and engineering domains.
