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 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.
Activity 27
Look at the map and the time zones.
Activity 28
Look at the world time zone map and decide:Which autonomous community in Spain is in a different time zone than the rest. What time is it in that autonomous community when it's 12 p.m. on the mainland?
Activity 29
Why do the majority of nations in the European Union have the same official time while the countries might be in different time zones?
