Why is it Greenwich mean time?
In the days when navigators were just starting to use chronometers to pinpoint there position it was vital that they used a standard time (it still is, by the way). Because England was the primary naval power in the world the time that was chosen as the standard was the time at the prime meridian (0°E, 0°W), which runs through Greenwich, London. The reason for the prime meridian running through London was the same – England was the most influential country in the world when it was defined. GMT is also called UT, UTC and Zulu Time. Here is the the Greenwich Mean Time website. http://wwp.greenwichmeantime.
