Greenwich Time
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World Time and ClocksWorld Time and Clocks - Clocks are found all over the world and all tell you the same thing wherever you live. We've gathered information about world time and clocks. Things like daylight savings time, world time zones, atomic clocks & more.

The Greenwich Time is measured from the Greenwich Meridian Line at the Royal Observatory in Greenwich. It is the place from where all time zones are measured.

Greenwich Time (GMT)

Gmt (Click to enlarge)
GMT - The Prime Meridian Line

Greenwich Mean Time is a term originally referring to mean solar time at the Royal Observatory, Greenwich in England. It is now often used to refer to Coordinated Universal Time (UTC) when this is viewed as a time zone, although strictly UTC is an atomic time scale which only approximates GMT in the old sense. It is also used to refer to Universal Time, which is the astronomical concept that directly replaced the original GMT.

Historically the Greenwich Time has been used with two different conventions for numbering hours. The old astronomical convention (before 1925) was to refer to noon as zero hours, whereas the civil and more modern convention is to refer to midnight as zero hours. The more specific terms UT and UTC do not share this ambiguity, always referring to midnight as zero hours. Wikipedia

Greenwich, England has been the home of Greenwich Mean Time (GMT) since 1884. GMT is measured from the Greenwich Meridian Line at the Royal Observatory in Greenwich. It is the place from where all time zones are measured. World Time Zones

The most relevant links we could find, placed here free

Greenwich2000 - Check the current Greenwich Time.

World Time Zones - The current time anywhere in the world.

Wikipedia - Information about the Coordinated Universal Time (UTC).

About - "Understanding and Reading UTC or GMT Time", an article about GMT and differences with UTC.

Royal Observatory Greenwich - Site of the Royal Observatory in Greenwich, UK. Check highlights, history and more information.

Greenwich time (Click to enlarge)
Greenwich time

Greenwich Mean Time (GMT) began in the 19th century for use in British maritime navigation. Greenwich, England was established as the Prime Meridian with a longitude of zero.

While the UTC time was based on GMT time, there are two main differences between the two. UTC time is based on midnight while GMT is based on noon. Another difference between UTC and GMT time is that GMT is based on Earth's rotation and celestial measurements, UTC is a based on cesium-beam atomic clocks.

Greenwich Time (GMT) is also known as Zulu Time

The royal observatory (Click to enlarge)
The Royal Observatory

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