5. Time zones
Talking book
When it's 12 p.m. at the prime meridian (0° longitude), on the opposite side of the Earth at the 180th meridian (180° longitude), it's 12 a.m. The 180th meridian in the Pacific Ocean coincides with the International Date Line.
The Earth takes 24 hours to complete one rotation on its axis. Each of these hours is represented by a vertical strip called a time zone .
The extent in degrees of each time zone is determined in this way: The Earth's sphere has 360°. This is divided into the number of hours the Earth planet takes to complete one rotation (360° divided by 24 hours = 15°). So, each hour is equal to 15° of longitude.
The prime meridian or Greenwich meridian is the starting point for the time zones around the world. It is called GMT . If you travel east from this point you add an hour for every time zone you cross; but if you travel west, you subtract an hour for each time zone (or 15° of longitude).
Time zones are mainly used to establish the time difference between different regions and countries of the Earth.
Time zone map
Weblink 7: Time zone map
Video 6 : Time zones