Time zones across the world

Time zones are set up across the world to avoid confusion in timing. The whole world is divided into 24 time zones. Within each zone the time is the same, and the difference between one zone and the next is exactly one hour. Greenwich (London), England, was selected as the starting point. Thus, when it is noon in Greenwich, the time in the next zone eastward is 1 P.M. the time in the next zone westward is 11 A.M. in new York, five zones west of Greenwich, the time is 7 A.M. the united states is divided into four zones based on the 75th, 90th, 105th, and 120th meridians.

The times in these zones are called eastern, central, mountain, and Pacific Standard Time. On the opposite side of the world from Greenwich is another dividing line, the International Date Line. This line is approximately the 180th meridian. When it is noon at Greenwich it is midnight at the International Date Line. Crossing the line, a person gains or loses a day, depending on weather he is moving east or west.