May 23, 2021 1:02 PM
Have you ever noticed while watching television that when a commercial promotes a new episode, they mention different time zones? That's because Earth is divided into 24 different regions that each have a different time. These regions are separated by longitude lines that are roughly 15 degrees apart. So depending on which way you travel, time moves forward or back an hour for each 15 degrees of longitude that you go through.
We have time zones because it wouldn't make sense for it to be the same time everywhere in the world at once. If that was the case, noon might be in the sunniest part of the day for some people but at bedtime or early in the morning for others. Since the sun strikes different parts of the planet at different times, it makes sense to have time zones so that the sun always sets when your clock says it's nighttime and rises when your clock says it's morning.
Time zones are generally separated by longitude lines every 15 degrees. However, it isn't a perfect fit; sometimes, the borders of time zones are moved to align with international boundaries instead of rigidly adhering to the longitude rule. It would be confusing for everybody if the next town over was in a completely different time zone, especially in a small country!
There are 24 time zones around the world because there are 24 hours in a day. There are 360 degrees of longitude around the globe. Dividing 360 by 24 gives you 15 degrees of longitude, which is why time zones are roughly 15 degrees wide.
In the 1700s, an English clock-maker named John Harrison figured out that you could use a clock with to calculate a ship's longitude at sea. He invented a device called a marine chronometer, which could be used to calculate the difference between the observed local time and the time at Greenwich, England (Greenwich Mean Time). This could then be used to determine the ship's longitude. His work connecting time with longitude led to great improvements in marine navigation and safety.
However, many cities around the world still based their clocks based on when the sun rose and set until the American railroads became a commonly used mode of transportation. Train travel could be challenging and even dangerous because every station set its own time; it was difficult to set train schedules and keep multiple trains running over the same tracks safely without consistent clocks. This led to the U.S. adopting four standard time zones in 1883. In the years that followed, the prime meridian was designated as the line of longitude running through Greenwich, England, and global time zones would be calculated from there.
Discover Time Zones: This activity asks you to determine the time zones of several different observing sites on a map.
Understanding Time Zones: In this activity, you can create your own time zone model and determine the time in different spots all around the world.
All About the Time Zones Activity Sheet: Find the missing words to complete the sentences about time zones and find hidden words in the word search.
Geography and Time Zones: BrainPop can help you learn more about time zones with an educational video and a quiz to test what you learned.
Why Do We Have Different Time Zones? Have you ever wondered why we have different time zones? Wonderopolis gives a detailed answer about what time zones are and why they exist in the first place.
Understanding Time Zones: Read about what time zones are in an article compiled from research that kids just like you have done on their own and in school!
Understanding Time Zones Lesson: This video gives an overview of how time zones work. Watch and learn, then take the quiz to see how much you remember.
What Are Time Zones? Learn about the science behind how the sun moves and how we created time zones.
World Time Zones: This page has an interactive world time zones map as well as information about why time zones work and why the sun rises and sets at different times.
Academic Kids Encyclopedia: Time Zones: This encyclopedia entry gives a brief overview of time zones.
Time Zones: Watch a video from the BBC that examines the geography of time zones.
Time Zones Puzzle: Match the clock to the correct time zone in this game.
Exploring Time Zones: This document has a bunch of fun activities that can help to teach you all about time zones.
Latitute, Longitude, and Time Zones: This page includes games and activities to help you learn more about latitude, longitude, and time zones.
Time Zones: Their Invention and Implementation: Find out more about how timekeeping has evolved over the years and how time zones were created.
Create Your Own World Clock: Here's a fun craft that lets you create your own world clock with just cardboard, art supplies, and scissors.
Weird Science: The Prime Meridian and Time Zones: This page covers the science of the prime meridian and the creation of the different time zones.
Geography Basics: Latitude and longitude are used in the study of geography, to create maps, and to help outline the boundaries of time zones.