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Have you ever thought about how it is day in India and night in the United States? It's because of time zones. You might have heard of EST, IST and many others but how many time zones are there all over the world? Let’s find out!
How Many Time Zones Are There in the World?
The answer is that there are 24 time zones. This number is derived from the fact that the Earth is a sphere and it takes 24 hours to complete one rotation. Further, a full circle is 360 degrees and if you divide 360 by 25 you will get 15 degrees. So, a change in the time zone starts every 15 degrees.
Simple, right? But there's a catch. Well, there actually aren't 24 time zones in the world. The world has around 38 to 40 time zones.
Why? This is because many countries have shifted their time zones for a variety of political, economic or other purposes. Some locations also use a half hour or even a quarter hour (15 minutes) from UTC (Coordinated Universal Time).
For example, India has I.S.T. (Indian Standard Time) which is UTC+5:30. So India has a 30 minute difference in comparison to most countries. Nepal goes even further (UTC+5:45).
What Is UTC?
UTC is Universal Time Coordinated commonly known as Coordinated Universal Time. It's the "international master clock". Every country’s time is related and measured by UTC.
The National Oceanic and Atmospheric Administration mentions: “UTC literally stands for Universal Time Coordinated (though it is typically referred to as Coordinated Universal Time) and is the standard time common to every place in the world. It is also known as Greenwich Mean Time (GMT) and Zulu (Z). UTC is defined as the time at longitude 0 degrees, the prime meridian. This is the longitudinal line that separates the Eastern and Western Hemispheres, and happens to pass through the Greenwich Observatory outside of London, England. All of our forecast products and the computer models that provide us guidance are based on this universal time zone.”
For example, it's UTC-5 in the winter (Eastern Standard Time) in New York, US. Whereas India is UTC+5:30.
What is The International Date Line?
The International Date Line is at 180 degrees, and it is on the opposite side of the earth from the Prime Meridian (0 degrees). For example If you travel East you will lose a day. But if you are travelling to the West, you move forward a day. That is why a flight sometimes makes you feel that you lost a day.
Why are Time Zones Important in Daily Life?
Time zones affect everything from business meetings to air travel, to sporting leagues to the release of entertainment. If you are in Mumbai and watching a live NBA game from the USA, it is something that is happening 11.5 hours prior to your time.
There are 24 time zones as per the textbooks, but politically there are 38-40 time zones, because of the division of the world by national boundaries and the odd adjustments. Not everything is neatly divided.
So next time you use a clock for an international meeting or phone call, you will be able to do tricky maths!
