The Earth spins on an imaginary pole called its “axis.” Every 24 hours, the Earth makes a complete rotation — or one full turn — on its axis. We call each full turn a day.

Imagine shining a flashlight at a globe. Only part of the globe would receive light, while the opposite side of the globe would be dark. As the Earth rotates, different parts of the Earth receive sunlight or darkness, giving us day and night.

As your location on the Earth rotates into sunlight, you see the sun rise. When your location rotates out of sunlight, you see the sun set.

If we had one single time zone for Earth, noon would be the middle of the day in some places, but it would be morning, evening and the middle of the night in others. Since different parts of the Earth enter and exit daylight at different times, we need different time zones.

In the late 1800s, a group of scientists figured out a way to divide the world into different time zones. In order to build the time zone map, they studied Earth’s movements.

As the Earth rotates on its axis, it moves about 15 degrees every 60 minutes. After 24 hours, it has completed a full circle rotation of 360 degrees.

The scientists used this information to divide the planet into 24 sections or time zones. Each time zone is 15 degrees of longitude wide.

Distance between the zones is greatest at the equator and shrinks to zero at the poles, due to the curvature of the Earth. Since the equator is approximately 24,902 miles long, the distance between time zones at the equator is approximately 1038 miles.

The imaginary dividing lines begin at Greenwich, a suburb of London. The primary dividing line of longitude is called the “prime meridian.” Longitude is the angular distance between a point on any meridian and the prime meridian at Greenwich.

The time at Greenwich is called “Greenwich Mean Time” (GMT). As you move west from Greenwich, every 15-degree section or time zone is an hour earlier than GMT, while each time zone to the east is an hour later.

Having different time zones means that no matter where you live on the planet, your noon is the middle of the day when the sun is highest, while midnight is the middle of the night. Let’s take a closer look at how this works.

Let’s say you live in Charlotte, North Carolina, and you have a cousin who lives in Madrid, Spain. Charlotte is five time zones to the west of Greenwich, which is written as GMT -5. Madrid is 1 section east of Greenwich (GMT +1). This means Charlotte and Madrid are six time zones apart.

When your cousin is eating lunch at noon Madrid time, you are probably just getting out of bed to get ready for school. This is because at 12:00 P.M. in Madrid, it’s only 6:00 A.M. in Charlotte. On the other hand, if you wanted to chat with your cousin online after dinner at 6:00 P.M., it would already be midnight in Madrid!


22 Join the Discussion

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  1. Wow I must’ve moved 2 time zones because I used to live in Colorado and now I live in South Carolina so it was 10:00 for me when it was 12:00 and already time to eat lunch!!!

    • You’re right, Ameroxs! We learned that Colorado is two hours behind South Carolina in time. Sometimes it’s written this way: Colorado (UTC-7) and South Carolina (UTC-5). When you were eating lunch at noon in South Carolina, your friends in Colorado were probably finishing breakfast at 10:00 a.m. ! :)

    • That’s great new, Whitefox66! We are glad you’ve been WONDERing with us– it’s fun to learn something new every day! :)

  2. Hi my name is Siddaarth and I am from Mrs. Caplin’s class. This miraculous wonder had a very nice topic to it, because I learned a bunch of brand-spankin’ new facts. Some of the facts I learned were that when the Earth moves on its axis, it moves about 15 degrees every 60 minutes. Or, the Equator is about 24,902 miles long. Were the time zones just the different areas were light was shining and did not shine on? Using my PC (personal connection) I remember when I went on a trip to California to visit my uncle, I had to adjust my watch to a different time zone because, the place were I live has a different time zone. Using my BK (background knowledge) in my school when we did social studies, there was a paper that I had to read that was about time zones. I predict the next wonder will be about weird traders, because boots are more expensive than sandals.

    • Hey Siddman! Welcome back to Wonderopolis! We think you did a great job using your personal connection and relating it to this Wonder. The reason you had to change the time on your watch was because of the time zone difference from Ohio to California! Thanks for sharing your comment, and your guess for the next Wonder! :)

    • HOORAY, we’re glad this Wonder helped you understand time zones, Tan Zheng Hau! Thanks for WONDERing with us– we can’t wait to see you again! :)

    • Thanks so much, Blue, 123abc, and Bluecupquake11! We are so glad you enjoyed this Wonder- we’re glad you visited Wonderopolis today! We Wonder what time zone you live in? :)

  3. Thanks for your information and analysis it gives enough understanding of the earth time zone at least to better my knowledge. I will appreciate more of these information.

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Have you ever wondered…

  • Why do we have different time zones?
  • How long does it take the Earth to make one full rotation on its axis?
  • What is the prime meridian?

Wonder Gallery

Wonder #121- Time Zone Static ImageVimeo Video

Try It Out

Ready, set, glow! Let’s find out who’s sleeping when you’re having lunch. Grab a globe and a desk lamp, and let’s get glowing.

Set the globe on a flat surface directly across from the desk lamp. The lamp will represent the sun. Turn down all the other lights in the room.

Begin by locating Greenwich on the globe. Aim the light directly at Greenwich. This represents noon, the brightest time of day.

The opposite side of the globe is farthest from the sun, which also makes it the darkest. This represents midnight.

Now find your hometown on the globe. Rotate the globe so your hometown is pointed directly at the sun.

Look at the opposite side of the globe. When it’s noon at your location, where is it the middle of the night?


Still Wondering

Want to learn more about those imaginary lines on maps? Visit National Geographic Xpeditions for a fun and informative Introduction to Latitude and Longitude!


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