Greenwich Mean Time (GMT) is a term originally referring to mean solar time at the Royal Observatory in Greenwich, London. It is commonly used in practice to refer to Coordinated Universal Time (UTC) when this is viewed as a time zone, especially by bodies connected with the United Kingdom, such as the BBC World Service, the Royal Navy, the Met Office and others, although strictly UTC is an atomic time scale which only approximates GMT with a tol...
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Greenwich Mean Time (GMT) is a term originally referring to mean solar time at the Royal Observatory in Greenwich, London. It is commonly used in practice to refer to Coordinated Universal Time (UTC) when this is viewed as a time zone, especially by bodies connected with the United Kingdom, such as the BBC World Service, the Royal Navy, the Met Office and others, although strictly UTC is an atomic time scale which only approximates GMT with a tolerance of 0.9 second. It is also used to refer to Universal Time (UT), which is a standard astronomical concept used in many technical fields and is referred to by the phrase Zulu time.
In the UK, GMT is the official time only during winter; during summer British Summer Time is used. GMT is substantially equivalent to Western European Time.
Noon Greenwich Mean Time is not necessarily the moment when the noon sun crosses the Greenwich meridian (and reaches its highest point in the sky in Greenwich) because of Earth's uneven speed in its...
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