How Many Time Zones Does The World Have?
By: Shahzad Bashir
What are Different Time Zones? | How is Time Calculated Worldwide?
We know that the clocks in America, China, and Bangladesh show totally different times. Based on the distance and location, countries follow different time zones, some countries have only a few minutes offset, and some are a day apart. Even the countries that are so big follow 11 different time zones, and others use just one. It depends on the geographical area a country is covering, and countries also have offshore territories. In 1878, Sir Sandford Fleming introduced the idea of time zones, and it was first used by America’s railroads in 1883.
There are 24 time zones worldwide, as each time zone has a one-hour difference. Days are split into seconds and calculated to evaluate the exact time of a particular place. Based on the Earth’s rotation, astrologers observe celestial bodies crossing the meridian to measure the time. According to some astrologers, the observance of stars crossing the meridian would tell a more accurate time than the observance of sun positions. To order the date and time globally, we follow Co-ordinated Universal Time (UTC).
If it is the first time you have ever come across the concept of time zones, it might take you some time to understand how it is measured and why the world has different time zones ranging from UTC-12 to UTC+12. This article discusses different time zones, and how to calculate time zones.
What is Co-ordinated Universal Time (UTC)?
UTC is a variant of Greenwich mean time at zero-degree longitude. It compensates for the slowing rotation of Earth by adding leap seconds to days regularly. With Greenwich meridian, UTC uses negative and positive to show time zone offsets from UTC. For instance, the easternmost time zone is 12 hours behind UTC, and the westernmost time zone is 12 hours above UTC, so it uses UTC-12 and UTC+12 tags accordingly.
Things You Need to Know About Time Zones
Why is the Time Zone 15-degree longitude?
It is something related to the rotation of Earth. Every 60 minutes, our planet Earth moves 15 degrees on its axis. To complete its full rotation of 360 degrees, it took 24 hours. Based on these numbers, there are a total of 24 sections of time zones, and every time zone is 15-degree longitude.
24 Time Zones
Based on 15-degree longitudinal time zone calculations, every time zone is 1 hour apart, so there should be 24 time zones worldwide. Now, there are 3 more time zones added to the list by International Date Line (IDL). There are some time zones only 30 to 45 minutes apart; it has further increased the number of time zones.
Daylight Saving Time
Daylight Saving Time or DST is a practice of setting the time one-hour forwards in summers and moving it back in winters. The reason why we use DST is to get some extra hours of daylight.
The time and name of time zones changes during Daylight Saving Time. With the time zone name, “Daylight Saving Time” or “Summer” are also included. In this case, there is a 1-hour extension in the local time. For instance, the United States uses Pacific daylight time during daylight saving time period with UTC-7. However, throughout the year the USA uses pacific standard time with an offset of UTC-8.
Time Zone Borders
One hour time difference indicates solar meantime, and it is 15 longitudinal degrees wide. When you see your time zone map, there are white and gray stripes on them representing time zone borders. The aim of the time zone borders map is to match with international and internal time borders, but your local time is not always a 15-degree longitudinal time zone. There are some countries large in size but still follow one time zone for social, commercial, and legal purposes; for instance, there is a one-time zone in
China and India.
Based on their large area, they could have multiple time zones like Russia and Canada, but they prefer following one time zone. So, there is no such hard rule for any country; it is their choice whether they want to follow one time zone or choose multiple times for different cities.
It Is Not Local Time
Time zone and local time are two different terms, mostly confused as synonyms. For example, two cities might have different time zones but still have the same local time. So, during DST, clocks at California and Arizona show the same time, but you can’t say California and Arizona have the same time zone; it would be more accurate to say, California and Arizona have the same local time.
One thing to note here is that Arizona has no DST, so its standard time remains the same throughout the year, which is UTC-7. On the flip side, California local time keeps changing in summers and fall. During DST, there is a UTC offset of UTC-7; however, the standard time of California is UTC-8.
How does UTC Define Time Zone?
The time of every region globally is calculated based on its distance from Greenwich, London, UK. Greenwich is a reference point of UTC with a one-hour extension for every 15-degree distance. To split all regions of the Earth into 24 time zones, we divide longitude by 15 degrees to calculate the exact time zone in hours. For instance:
At 75º west longitude, we calculate the time zone by dividing 75 degrees by 15 degrees. There will be 5 hours offset from UTC, that is UTC-5.
At 150º east longitude, we calculate the time zone by dividing 150 degrees by 15 degrees. It will be 10 hours ahead of UTC, that is UTC+10.
Using this formula for time calculation, you can find out the time for any region from the globe. One thing you have to consider is, some regions have different local times and time zones, so time zones would not always tell you the standard time a country or city is following.
What is Jet Lag?
It is a psychological state mostly faced by people traveling long distances through airlines. Especially, when they travel through different time zones, they start feeling down because of an instant change in their body’s internal clock. They feel that it is either too early or too late. Jet lag also happens because long-distance travel can disturb the natural sleep rhythm and cause short-lived sleep issues. This condition can last up to hours, days, and sometimes takes weeks to start feeling normal about your time.
Countries With Highest Number of Time Zones:
Following are the top 5 countries with the most number of time zones.
This country has the most scattered territories, and as a result, there are 12 different time zones. These time zones range from UTC-10 to UTC+12. French Polynesia is an overseas collectivity of France, and this region is also the main reason for the high number of time zones. The time zones of France are as follows: UTC-10, UTC-9:30, UTC-9, UTC-4, UTC-3, UTC+1, UTC+3, UTC+5, UTC+11, and UTC+12.
There are 11 time zones in the United States of America, out of which 6 time zones are over the mainland. This country’s time zones range from UTC-12 to UTC+12. Out of these time zones, two time zones (UTC-12 and UTC+12) are not official yet. The time zones followed by the USA are UTC-12, UTC-11, UTC-10, UTC-9, UTC-8, UTC-7, UTC-6, UTC-5, UTC-4, UTC+11, and UTC+12.
It is one of the biggest countries in the world, having 11 different time zones. Russia is the only country where all time zones are on the mainland. This is the country with the most consecutive time zones ranging from UTC-2 to UTC-12. The time zones of Russia are UTC-2, UTC-3, UTC-4, UTC-5, UTC-6, UTC-7, UTC-8, UTC-9, UTC-10, UTC-11, and UTC-12.
The United Kingdom’s mainland is not very large; it is just a small island-like country in the north of the Atlantic Ocean. If you have studied history, we would know that the British had created colonies globally. This is the main reason why this country has several time zones spread throughout the world. From their Indian ocean territory to Pacific Ocean Pitcairn islands, there are 9 different time zones, which are: UTC-8, UTC-5, UTC-4, UTC-3, UTC-2, UTC (GMT), UTC+1, UTC+2, and UTC+6.
It is the 6th largest country in the world with 8 time zones. The overall landmass of Australia and the islands that come under its territories cover the whole south continent of Oceania. The time zones of Australia are UTC+5, UTC+6:30, UTC+7, UTC+8, UTC+9:30, UTC+10, UTC+10:30, and UTC+11.
The above-mentioned countries have the highest number of time zones around the world. The main reason why a country has more than a one-time zone is its geographical area. If the country is too big or has national territories outside the mainland, it would increase the chances of a country having various time zones. Although, a country is not always obliged to follow multiple time zones. China and India are examples of countries with large geographical areas, but still, they follow one standard time throughout the country.
Reading this article, now you have understood what time zones are and how they differ throughout the world. The idea of a time zone is not older than a century or so, and it has proved quite useful for international businesses, politics, economies, etc. It seems almost impossible now to function without time.
Next time, whether you are planning a tour to a far-off place, or want to grow your business to a foreign country, the time zone is something you should consider.