Ever since mankind began to measure time, it has had to face a daunting challenge: how to synchronize time across the entire world?
The answer to this question lies in a simple but brilliant idea: the division of the Earth into 24 time zones.
Each time zone represents an area where the time is the same throughout the year.
But why 24? Why not 12, 36 or even 100? To understand this decision, we must delve into the depths of history, science and geography.
The rotation of the Earth: a natural clock
To understand this concept, we must first understand how the Earth rotates on itself.
Our planet makes a complete rotation on its axis in 24 hours. This is why a day consists of 24 hours. If we imagine the Earth as a perfect sphere, the imaginary line that divides the Earth into two hemispheres, called the equator, is about 40,000 kilometers long.
If we divide this distance by the number of hours in a day, we get a distance of approximately 1667 kilometers. It is therefore the width of a time zone.
But beware, it’s not that simple. Due to the elliptical shape of the Earth and its tilt on its axis, the width of time zones actually varies. Nevertheless, this approximation allows us to understand why we have 24 time zones.
The role of science in the standardization of time
Another essential element in this story is the influence of science on the determination of time zones.
- Navigation: In the age of great discoveries, navigators needed an accurate method to determine their longitude at sea. That’s why they started using time to solve this problem. By knowing the exact time at a fixed location (for example, Greenwich in England) and comparing that time to local time, they could determine their east-west position. This is called the longitude method.
- Astronomy: Astronomers have also contributed to the definition of time zones. By observing the movement of the stars, they were able to determine the time with incredible precision, which helped synchronize clocks around the world.
- Technology: With the advent of railways and telegraphs in the 19th century, the need for standardized time became apparent. Time zones were therefore created to facilitate communication and transportation.
The political and social challenges of implementing time zones
Creating time zones was not an easy task.
She had to face many political and social challenges.
- The choice of the meridian of reference: The first difficulty was to choose a reference point from which the time zones would be defined. In 1884, during the international meridian conference, the meridian of Greenwich, England, was chosen. This was prompted by the fact that most of the world’s shipping already used Greenwich as a reference.
- National and regional borders: The second difficulty was to match time zones to national and regional borders. For political and practical reasons, it was decided not to strictly respect the geographical limits of the time zones. This is why some countries, such as China and India, have only one time zone, despite their large size.
- Adaptation of the populations: Finally, the adaptation of the populations to this new organization of time was also a challenge. It took time for people to understand and accept the idea of time zones. Also, some places have chosen not to follow time zone rules exactly, such as Iceland which uses Greenwich Mean Time all year round, despite its geographic location.
Exceptions and peculiarities of time zones
Finally, it is important to mention that the time zone system is not perfect and has many exceptions and peculiarities.
As mentioned earlier, some countries have chosen to have a single time zone, despite their large size. This is the case for China, which uses Beijing time nationwide, and India, which uses India Standard Time.
Additionally, some countries have time zones that do not correspond to a full hour from Greenwich Mean Time. For example, India is at GMT+5:30, Nepal is at GMT+5:45, and Lord Howe Island in Australia is at GMT+10:30.
There are also countries that change their time zone depending on the season, to take advantage of daylight, as is the case in many European and North American countries with the daylight saving time system.
Finally, there are extreme cases, such as Antarctica, where there is no official time zone. Research stations generally use the time of the country of origin of the current mission.
The division of the world into 24 time zones is the result of a long process that involved science, politics and society. Although not perfect, this system synchronizes time across the world and facilitates communication and travel.
It’s a fascinating example of how humanity has used its knowledge and ingenuity to solve a complex problem.
I am a student and I am part of the editorial staff of joehovasmf.com. I have the chance to enjoy writing, however, I also like to discuss all subjects and especially anything related to Science.