Studyfin
✨ Sign up free
Hey there! Have you ever wondered why it is breakfast time for you, but bedtime for a friend across the world? Let's explore how our spinning Earth creates different time zones!
The Earth is a giant sphere that rotates, or spins, on its axis. As it spins, the Sun can only light up one half of the planet at a time. When your side of Earth faces the Sun, you experience daytime, while the other side is in darkness.
Because one full spin of the Earth traces a complete circle, we divide that turn into 360 degrees. It takes 24 hours for the Earth to make one full spin. If we divide 360 degrees by 24 hours, we find that the Earth rotates exactly 15 degrees every hour. This is why each time zone is about 15 degrees wide!
We start counting time zones from a starting line called the Prime Meridian in Greenwich, England. If you travel east from this line, you go forward in time and add hours. If you travel west, you go backward in time and subtract hours.
Your cousin lives in London, England, which is on the Prime Meridian (0°). You live in New York, which is 5 time zones to the west. If it is 6:00 PM in London, what time is it in New York?
- Identify your starting point and starting time. London is at the Prime Meridian, and the time there is 6:00 PM.
- Determine the direction of travel. New York is located to the west of London.
- Recall the direction rule: traveling west means we must subtract hours.
- Count backward by the number of time zones. Since New York is 5 zones west, subtract 5 hours from 6:00 PM.
- Calculate: 6:00 PM minus 5 hours equals 1:00 PM. So, it is 1:00 PM in New York!