Table of Contents (click to expand)
- TheImpact Of Civilization On Timekeeping
- Why 24 Hours?
- Decans – Timekeeping Using Stars
- Why 60 Minutes And 60 Seconds?
- Back To Decimals
The reason that there are 24 hours in a day and 60 minutes in an hour is because of the way that the Egyptians and Babylonians divided up the day. They used a base 12 and base 60 system, respectively, in order to make it easier to count on their fingers.
In recent years, what is one of the most common answers we give in response to any question we’re asked, a request made of us, or a suggestion of how we spend our time?
Obviously, it is no wonder that we never have time to think about the TIME we have? Not even the TIME we have, but the way we organize it! Confused? Let me clarify.
Have you ever wondered why the wristwatch strapped to your arm (assuming you still use one) or any other damn clock shows 12 numbers signifying 12 hours? Why isn’t it some different random number, like 28 or 16? What is the significance of twelve in our perception of time? I mean, if you give it any thought, you can’t deny that our time-measuring system is pretty heterogeneous. Let me explain:
- 24 hours are divided into two parts—a day lasting 12 hours and a night lasting 12 hours.
- 1 hour contains 60 minutes, which alsohas 60 seconds each.
- Each second is then divided into 1000 milliseconds.
Now, this seems like a rather strange way to divide a day. No wonder kids have trouble learning how to tell time! But, as with every other thing in the world, there is also an explanation for this.
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TheImpact Of Civilization On Timekeeping
In today’s world, we widely use the decimal number system (base 10), which is believed to have originated because it made it easy for us to count things with our fingers.
Back then, when humans were still exploring the wonders ofnature and finding answers to their countlessquestions, many other numerical systems were commonly used. The Egyptians and Babylonians, who first divided the day into smaller parts, used duodecimal (base 12) and sexagesimal (base 60) numeral systems.
That obviously begs the question—why base 12 and base 60? The reason is simple, yet it may surprise many.
Yes, believe it or not, the structure of our fingers is precisely the reason! The number of finger joints on each hand (excluding the thumb) makes it possible to count to 12 by using the thumb. Surprised atwhat a simple explanation that is? Well, things are going to get slightly more complicated…
Also Read: Why We Should Use Base-12 Instead Of Base-10?
Why 24 Hours?
Let’s try to understand this step-by-step. 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. This T-shaped instrument would display time by casting a shadow on one of these 12 parts based on the Sun’s position in the sky.
However, this system worked well during the day when Sun was present. The absence of sunlight made it very difficult to ascertain the time at night. It’s pretty interesting to learn how they coped with this challenge.
Also Read: Why Do We Have Seven Days In A Week?
Decans – Timekeeping Using Stars
The ancient Egyptians used stars to calculate the time at night. They did this by paying close attention to a group of 36 special stars called “decans.” These stars rose in the sky in a pattern and were used to keep track of the hours. However, only about 12 of these stars out of 36 were visible at a given time, and which stars appeared changed with the seasons and the calendar year.
Now, the Egyptians made special charts called star calendars to keep track of the time using stars correctly. These charts had 36 columns for each decan and 12 rows for each hour that could be counted during the night.
Eventually, this timekeeping process was standardized with days and nights, each having 12 hours. However, this system only worked well during equinoxes, when the Sun was directly above the equator, dividing days and nights into equal lengths. At other times, the length of an hour would vary. For example, hours during the day in summer would be longer, while shorter in winter.
However, at that time, the hours did not have a fixed length. The Greek astronomers who were then trying tofind answers to the queries of the universe, existence, and stars and galaxies (in short… astronomers) found it difficult to manage calculations with the prevailing method. Then, Greek mathematician Hipparchus gave us the “Equinoctial hours” by proposing the division of a day into 24 equal hours. Even then, for a long time, ordinary people kept using the seasonally varying hours. It wasn’t until the 14th century in Europe, when mechanical clocks came into use that commoners began using the system that we practice today.
Also Read: Why Is A Full Circle 360 Degrees, Instead Of Something More Convenient, Like 100?
Why 60 Minutes And 60 Seconds?
The Greek astronomers who helped us make life simpler by equally dividing 24 hours followed the Babylonian’s sexagesimal (base 60) system for astronomical calculations. So, for convenience, they further divided an hour into 60 minutes and each minute into 60 seconds. It is unknown why the Babylonians used a base 60 system, but it may be because 60 is a special number for fraction calculations. It is the smallest number divisible by the first six counting numbers and by 10,12,15, 20 and 30. In fact, we have borrowed this idea from Babylonians not just for calculating time but also for calculating degrees in geometry. This is also why a circle has 360 degrees instead of a number that may seem more intuitive, such as 10 or 100.
Back To Decimals
Measuring time in hours, minutes, and seconds has sufficed for most purposes for a very long time. However, advancements in communication technology have required even more precise time measurements. Since we were already familiar with the decimal number system for many calculations, it made sense to divide a second into 1000 parts, known as milliseconds, for more precision. In addition, with further advancements in telecommunications, finance, and engineering, the need for even more precise time measurements has arisen. As a result, we now use even finer units of time, like microseconds and nanoseconds, in time-sensitive applications like GPS, high-frequency trading, and synchronizing computer networks.
Now, isn’t that interesting? The elegant ideas of our ancestors still rule our day-to-day lives thousands of years later. Now go out there, flaunt your newly increased knowledge of time, and make the best use of it!
Also Read: How Do You Measure A Second?
Do you remember why there are 24 hours in a day?
Can you answer a few questions based on the article you just read?
References (click to expand)
- Why is a day divided into 24 hours? (Intermediate) - Curious About Astronomy? Ask an Astronomer - curious.astro.cornell.edu
- (1900) Hipparchus and the Precession of the Equinoxes - JSTOR. JSTOR
- T Ainsworth. A Timeline of the Decans: From Egyptian Astronomical .... Queen's University at Kingston
- Richards E. G. (1998). Mapping Time: The Calendar and Its History. Oxford University Press
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Why 60 Minutes and 60 Seconds? The Greek astronomers who helped us make life simpler by equally dividing 24 hours followed the Babylonian's sexagesimal (base 60) system for astronomical calculations. So, for convenience, they further divided an hour into 60 minutes and each minute into 60 seconds.Why is there only 24 hours in a day? ›
Our 24-hour day comes from the ancient Egyptians who divided day-time into 10 hours they measured with devices such as shadow clocks, and added a twilight hour at the beginning and another one at the end of the day-time, says Lomb. "Night-time was divided in 12 hours, based on the observations of stars.Who decided there are 24 hours in a day? ›
The ancient Egyptians are seen as the originators of the 24-hour day. The New Kingdom, which lasted from 1550 to 1070 bce, saw the introduction of a time system using 24 stars, 12 of which were used to mark the passage of the night.Who decided the number of hours in a day? ›
Hipparchus, whose work primarily took place between 147 and 127 B.C., proposed dividing the day into 24 equinoctial hours, based on the 12 hours of daylight and 12 hours of darkness observed on equinox days.Why aren t there 60 hours in a day? ›
The reason that there are 24 hours in a day and 60 minutes in an hour is because of the way that the Egyptians and Babylonians divided up the day. They used a base 12 and base 60 system, respectively, in order to make it easier to count on their fingers.Why don t we use 24-hour time? ›
Early mechanical clocks showed all 24 hours, but over time, clockmakers found the 12-hour system simpler and cheaper. Of course, a.m. stands for ante meridiem, which is Latin for "before midday." And p.m. means post meridiem — "after midday."Is there actually 24 hours in a day? ›
On Earth, a solar day is around 24 hours. However, Earth's orbit is elliptical, meaning it's not a perfect circle. That means some solar days on Earth are a few minutes longer than 24 hours and some are a few minutes shorter.
Who decided on these time divisions? THE DIVISION of the hour into 60 minutes and of the minute into 60 seconds comes from the Babylonians who used a sexagesimal (counting in 60s) system for mathematics and astronomy. They derived their number system from the Sumerians who were using it as early as 3500 BC.What year did 24 hour start? ›
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In the 24-hour clock format, each day runs from midnight to midnight and is divided into 24 hours. 24-Hour Time uses the numbers 00:00 (midnight) until 23:59 to tell the time.
The eight-hour workday started its life as a socialist dream. The Welsh textile mill owner and social reformer Robert Owen is credited as the first person to articulate it, by calling for “eight hours labor, eight hours recreation, and eight hours rest” for workers in the early 19th century.Who decided on 8 hour work days? ›
8-Hour Work Day. On August 20, 1866, the newly organized National Labor Union called on Congress to mandate an eight-hour workday. A coalition of skilled and unskilled workers, farmers, and reformers, the National Labor Union was created to pressure Congress to enact labor reforms.Who came up with 40 hours a week? ›
1926: Henry Ford popularized the 40-hour work week after he discovered through his research that working more yielded only a small increase in productivity that lasted a short period of time.Is 23 hours 56 minutes 4 seconds in a day? ›
On Earth, a sidereal day lasts for 23 hours 56 minutes 4.091 seconds, which is slightly shorter than the solar day measured from noon to noon. Our usual definition of an Earth day is 24 hours, so the sidereal day is 4 minutes faster.Why is a second a second? ›
The second is defined by taking the fixed numerical value of the caesium frequency ∆ν, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9 192 631 770 when expressed in the unit Hz, which is equal to s−1. The wording of the definition was updated in 2019.Why are there 12 hours in a day and not 10? ›
The reason a new day starts at 12:00 goes back to ancient Egypt when the day was measured using sundials. The shadow on the face of a sundial tells the time, and the shadow depends on where the sun is in the sky. "When the sun is highest overhead and the shadow goes straight up to the top of the sundial, that's noon.Why is military time confusing? ›
Military time is primarily used to avoid confusion and ambiguity of the time. Since Universal Time requires the notation of a.m. or p.m. and uses a 12-hour clock this can be confusing. Prior to the United States military adapting to a 24-hour clock or military time, the 24-hour clock was used by ancient Egyptians.Why do they call it military time? ›
The military operates at all hours of the day and night, so it uses a 24-hour clock, commonly referred to as military time, to avoid confusion between a.m. and p.m. hours. This method of time-keeping can be traced back to the Navy during World War I as all allied armies began using it starting with the United Kingdom.What does 17 00 mean? ›
5:00 PM equals 17:00. 6:00 PM equals 18:00. 7:00 PM equals 19:00.How long is a true day? ›
A day is commonly divided into 24 hours of 60 minutes, with each minute composed of 60 seconds.
The reason for the nearly 4-minute difference between a sidereal day and a solar day is that in one day, the Earth travels about 1.5 million miles along its orbit. So it takes an extra 4 minutes of rotation to bring us back in line with the sun as compared with the day before.Are days getting longer? ›
They have confirmed that the Moon is edging away at a rate of 1.5 inches (3.8cm) every year. And as it does so, our days are getting ever so slightly longer.Who invented time as we know it? ›
ACCORDING TO archaeological evidence, the Babylonians and Egyptians began to measure time at least 5,000 years ago, introducing calendars to organize and coordinate communal activities and public events, to schedule the shipment of goods and, in particular, to regulate cycles of planting and harvesting.When did seconds get invented? ›
The first mechanical clocks to mark the second appeared in the 1500s, and in 1644 French mathematician Marin Mersenne used a pendulum to define the second for the first time, leading to the international adoption of grandfather clocks by the end of the 17th century.What year did 60 Minutes start? ›
It has been honored with almost every broadcast journalism award, including 25 Peabody awards for excellence in television broadcasting. 60 Minutes was created in 1968 by Don Hewitt and premiered on the 24th of September on CBS.What is 16 in military time? ›
The 24 hour, or military clock, is widely used among scientists to avoid the confusion of the standard AM-PM system.What is 24-hour clock called? ›
What is the 24-hour clock called? The 24-hour clock is also called railway/railroad time, military time and continental time.What time is 8pm in 24 hours? ›
|24-Hour Clock Time Conversion Table|
there are 9 hours.
The 12-hour clock can be traced back as far as Mesopotamia and ancient Egypt. Both an Egyptian sundial for daytime use and an Egyptian water clock for night-time use were found in the tomb of Pharaoh Amenhotep I. Dating to c. 1500 BC, these clocks divided their respective times of use into 12 hours each.Who came up with 9 5 hours? ›
The modern 9-to-5, eight-hour workday was invented by American labor unions in the 1800s and went mainstream by Henry Ford in the 1920s. Workers today are still prepared to accept the same shifts because we have become so accustomed to it.How long are humans supposed to work? ›
Scientists say the ideal daily working time is around 6 hours, and these should be concentrated in the morning. There are workers who boast about the long hours spent at the workplace as a mark of productivity.How many hours a day should humans work? ›
In the end, scientists generally agree that the ideal daily working time is around 6 hours, and more concentrated in the morning.Why work 5 days a week? ›
In 1926, the founder of the Ford Motor Company took his six-day-a-week operation down to five days per week, with no changes in employee compensation. He believed doing so would make his workers more productive—and more inclined to spend money during their downtime.What country has the lowest work week? ›
According to government data, at only 29 hours per week, Netherlands has one of the shortest average work weeks in the world. The country ends up having 4-Day work week despite not having official rules for it.Why the 40-hour work week is outdated? ›
In conclusion, the 40-hour workweek, a standard instituted in the early 20th century, may no longer be an optimal structure for today's evolving workforce and economy. The shift from manufacturing to information and service-based work and technological advancements have dramatically changed the nature of work.What president started the 5 day work week? ›
During the Depression, President Herbert Hoover called for a reduction in work hours in lieu of layoffs. Later, President Franklin Roosevelt signed the Fair Labor Standards Act of 1938, which established a five-day, 40-hour workweek for many workers.What is 40 per hour salary? ›
Frequently Asked Questions. $40 an hour is how much a year? If you make $40 an hour, your yearly salary would be $83,200.When did minimum wage start? ›
The federal minimum wage was introduced in 1938 at the rate of $0.25 per hour (equivalent to $5.19 in 2022). By 1950 the minimum wage had risen to $0.75 per hour. The purchasing power of the federal minimum wage has fluctuated; it was highest in February 1968, when it was $1.60 per hour.
The time it takes Earth to rotate so the sun appears in the same position in the sky, known as a solar day, is 24 hours. However, the time it takes Earth to complete one full rotation on its axis with respect to distant stars is actually 23 hours 56 minutes 4.091 seconds, known as a sidereal … day.Why is a day not 12 hours? ›
Refraction: Light Lingers
Another reason for why the day is longer than 12 hours on an equinox is because the Earth's atmosphere refracts sunlight. This refraction, or bending of the light, causes the Sun's upper edge to be visible from Earth several minutes before the edge actually reaches the horizon.
But the reason you won't fall off the Earth is because of the force of gravity. This pulls us towards the middle of the Earth, and keeps our feet firmly on the ground. Read more: Curious Kids: how does gravity pull things down to Earth? This is why we call the ground “below us” and the sky “above us”.Are there technically 23 hours in a day? ›
The sidereal day happens each time Earth completes a 360-degree rotation. That takes 23 hours and 56 minutes. The solar day — the one humans count in the calendar — happens when Earth spins just a little further, and the sun is at the same point in the sky as it was 24 hours ago.Why 365 days in a year? ›
The Short Answer: It takes approximately 365.25 days for Earth to orbit the Sun — a solar year. We usually round the days in a calendar year to 365. To make up for the missing partial day, we add one day to our calendar approximately every four years.Are days longer than nights? ›
The longest day is longer than the longest night, and the shortest day is longer than the shortest night, for the reason that sunrise occurs when the upper edge of the disk of the Sun appears on the horizon, and sunset is at the moment when the upper edge disappears below the horizon.Who invented 60 minutes in an hour? ›
Who decided on these time divisions? THE DIVISION of the hour into 60 minutes and of the minute into 60 seconds comes from the Babylonians who used a sexagesimal (counting in 60s) system for mathematics and astronomy. They derived their number system from the Sumerians who were using it as early as 3500 BC.Who invented 12-hour time? ›
In Mesopotamia the year was divided into 12 based on lunar patterns, which coincided with the 12 zodiac signs, which may have prompted the emergence of the 12-hour clock introduced by the Babylonians.Who invented military time? ›
This method of time-keeping can be traced back to the Navy during World War I as all allied armies began using it starting with the United Kingdom. To this day, the Department of the Navy maintains the United States official time, with the Master Clock facility at the U.S. Naval Observatory in Washington, D.C.