DICTIONARY DEFINITION OF GREENWICH MEAN TIME
pictured above: the royal observatory in greenwichgreenwich mean time in space |
What is Greenwich Mean Time?
Since 1884 Greenwich, London England has been the home of Greenwich Mean Time, or GMT. Greenwich Mean Time has other names such as Greenwich Meridian Time because it is measured from the Greenwich Meridian Line at the Royal Observatory in Greenwich. Greenwich is the place from where all time zones are measured. The Greenwich Meridian marks the starting point of every time zone in the world. Greenwich Mean Time (or Meridian) is the mean (average) time that the Earth takes to rotate from noon-to-noon. GMT is World Time and the basis of every world time zone which sets the time of day and is at the centre of the time zone map. GMT sets current time or official time around the globe. Most time changes are measured by GMT. Although GMT has been replaced by atomic time it is still widely considered as the correct time for every international time zone in the world.
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Greenwich Mean Time is international time, the basis of the world time clock. GMT marks precision time and military time, defines date and time and the exact time. The atomic time clock is adjusted by leap seconds to remain synchronised with GMT. Greenwich Mean Time is used in the International Space Station.