My Science School

               In 1884 an international conference decided that the 0 degree line of longitude, or meridian, would run through the Royal Observatory in Greenwich, England. As you move to the east from the Greenwich Meridian, the time is one hour ahead of Greenwich Mean Time for each degree you move. If you move to the west, time is one hour behind for each degree. Midday is the point where the Sun is highest in the sky, whichever time zone you are in.

               The amount of daylight varies with the seasons, so daylight - saving time or summer time, was introduced to make maximum use of daylight hours. In the northern hemisphere, clocks are reset one hour ahead in spring and one hour back in autumn. (In the southern hemisphere the seasons are reversed.

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