14 Little-Known Facts About Time Zones

Are you curious about time? Why are there so many different time zones around the world? Let’s explore this together!

1. GMT and UTC

GMT stands for Greenwich Mean Time, which refers to the average time at Greenwich. This was the first standardized method of international timekeeping. It is measured at the Royal Observatory in Greenwich, England, which is conventionally located on the Prime Meridian (0 degrees longitude) at latitude 51°28’38″N.

GMT is the first standardized method of international timekeeping.

GMT is calculated from noon one day to noon the next day. Since 1925, this unit has been replaced by UTC (Coordinated Universal Time). A day is now calculated from midnight of the previous day to midnight of the following day. UTC is based on atomic frequency standards and becomes more precise when measured using solar energy from a point on the Earth’s surface.

Due to the Earth’s rotation on its axis at a variable speed, leap seconds are added to UTC to maintain accuracy, keeping it within 0.9 seconds. Therefore, it is possible to see T23:59:60 (sometimes with a 60th second instead of 59). On January 1, 1972, UTC officially became the international standard time, although GMT is still widely used.

2. Boundaries of Time Zones

The difference is most evident in the vast countries of China and India.

The boundaries of time zones show considerable variation. This is because time zone boundaries must align with national borders. This discrepancy is most evident in the vast countries of China and India, where both nations use a single time zone throughout their territories.

3. Horizontal Time Zones

In one place in Australia, the time difference was adjusted by an additional 30 minutes due to business competition.

Time zones are divided along vertical lines and longitude, based on the movement of the Sun from east to west, but not everywhere adheres to this natural rule. In a commercial area in Adelaide, Australia, the local time zone is normally one hour behind Sydney, but due to business competition, an additional 30-minute adjustment was made.

4. A World Without Time Zones

Before the introduction of clocks, people calculated time based on sunrise and sunset.

Before the GMT standard was established, time was calculated by observing the sky or the ground. More sophisticated methods included observing the Sun at its zenith (noon) or using shadows (the shadow of an object changes with the movement of the Sun).

With the advent of clocks, people began to calculate time based on sunrise and sunset, leading to differences in time across regions. This was not a significant issue due to limited travel between territories. As communication and transportation improved, the need for standardized timekeeping became apparent.

5. The Sun at Zenith

The time of the Sun at its zenith is mostly accurate in other countries, except for China.

The time of the Sun at its zenith is generally accurate in most countries, except for China. This is because the country’s vast border spans up to 240 kilometers, yet it operates on a single time zone. As a result, the solar noon in the far west occurs at 3 PM, while in the far east, it is at noon.

China previously had five time zones, including: Kunlun (in Xinjiang-Tibet), Gansu, Sichuan, Zhongyuan, and Changpai. However, the country later adopted a single time zone for unification, causing difficulties for its citizens. For instance, people in Xinjiang work four hours later than in other regions because the Sun rises there at 10 AM.

6. A Common Time Zone for the World

In any country, 9 AM must be daytime, and 10 PM must be nighttime; this cannot change.

Wouldn’t it be easier and simpler to have a common time zone, just as we have common currencies and languages? And when traveling from one country to another, there would be no need to reset your clock. However, the reasons for the need for multiple time zones include: the Earth rotates 15 degrees each hour, and a full day is 360 degrees. Areas ahead of the previous time zone by one hour (except Japan) indicate the exact moment the Sun is at its highest. In any country, 9 AM must be daytime, and 10 PM must be nighttime; this cannot change. The only exception is in Northern Europe, where there are six months of day and six months of night.

7. The Smallest Time Zone

A small island in the Baltic Sea is divided into two time zones according to national boundaries.

A tiny island in the Baltic Sea is very small, with a distance of 80-300 meters between its farthest points. This island is owned by both Sweden and Finland, each controlling half, resulting in its time zone being split into two along national boundaries. This location is significant for both countries in calculating and formatting their time zones.

8. Neighboring Countries with a 24-Hour Time Difference

This is the story of American Samoa and the Line Islands; these two places are only 2000 km apart yet have a full 24-hour time difference.

9. France Has Up to 12 Different Time Zones

In practice, France primarily uses UTC +1 and shifts to UTC +2 during summer, but at almost any time, the entire country and its overseas territories span 12 different time zones.

Time zones in France.

Looking at the map of France, you will see that its provinces and overseas territories are all regions managed by France but located outside the geographical boundaries of Europe. Although these territories are far away, they still fall under French administration.

These territories are scattered across the globe, from some islands in the Atlantic and Indian Oceans, French Guiana on the South American mainland, to some small territories in Africa. And of course, they are at different longitudes. This leads to the diversity of France’s time zones. This is why France can have up to 12 different time zones, more than any other country in the world.

10. President Putin Eliminates Some Time Zones

Although Russia spans 11 time zones on the map, the actual number is only 9. At 2 AM on March 28, 2010, most of Russia moved its clocks forward by one hour, but regions like Udmurt, Samara Oblast, Kamchatka, and Chukotka remained unchanged by government decision. This move aimed to streamline business relations with Moscow and enhance domestic unity. That year, Crimea skipped two hours on March 30 to synchronize with Moscow.

11. India Only Has One Time Zone

Despite its vast size, India firmly uses only one time zone across the entire country. In the past, Indian cities had their own time zones, but during the colonial period, a unified time zone known as Madras Time was adopted to streamline the railway network.

12. Hawaii Does Not Observe Daylight Saving Time for Simplicity

In winter, Alaska shares the same time as Hawaii, even though the weather in the two places is completely opposite. Some regions of the United States, such as the Virgin Islands, Puerto Rico, Guam, and American Samoa, also do not observe daylight saving time.

14. Some Countries Do Not Use Whole Hour Time Zones

The time in Iran is GMT+03:30 and GMT+04:30 during the summer. Afghanistan operates on GMT+04:30, Sri Lanka on GMT+05:30, and Canada on GMT-03:30 and GMT-04:30 in the summer. Some areas even have a 15-minute difference, such as Western Australia at GMT+08:45, Nepal at GMT+12:45, and Chatham Islands in New Zealand at GMT+05:45.

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