What Is GMT?

Question

I got no idea what it is.

Answer 1

GMT is Greenwich Mean Time. It's an old time system, that used to be very close to mean solar time on the prime meridian at Greenwich, England.

GMT had "rubber seconds" -- to make the clock match solar time, they stretched the seconds a little bit ("frequency offset"). Also they would sometimes put in time bumps of 1/10 of a second. This got a bit confusing to users around the world, so in 1972 they switched to UTC = Coordinated Universal Time.

Every second in UTC is the same duration, and every day has the same number of seconds -- except for "leap seconds". These are put in every few years, to keep the UTC time close to the solar time.

Even though modern clocks are based on UTC, the old name GMT is still used, even when people really mean UTC.

Answer 2

It's Greenwich Mean Time. The Prime Meridian passes through Greenwich,UK so it's the time difference from the time in your time zone to Greenwich's time. It's represented with a plus for more and a minus sign for less. So let's just say as an example that you live in Furnace Creek,CA,USA and the time in Furnace Creek is 11:29:00 PT and the time in Greenwich is 4:29:00 GT so the GMT for Furnace Creek,USA at that time will be -5:29:00. Another example would be let's say you live in Sydney,NSW,Australia and the time is 6:31:00 am Sydney Time and in Greenwich the time is 8:31:00 pm so the GMT for Sydney is +10:31:00

Answer 3

Governments have set up all sorts of time zones...GMT..is just one of them. It is a way to know whatever time zone you are in to know what time it is somewhere else in the world. There is also a time the military uses no matter where they are located in the world so they can coordinate things at the same time without having to add or subtract hours and it is also the official time in the United states. GMT which is "World Time" is now known as coordinated universal time or UTC. Short for universal time. GMT was originated in Greenwich England for the Royal Navy......I could go on and on. It is basically a standard time Gage for governments to use.

Answer 4

courtesy of wikipedia.org

Greenwich Mean Time (GMT) 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 (UT), which is the astronomical concept that directly replaced the original GMT.

Answer 5

Greenwich Mean Time (GMT) 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).

Answer 6

Greenwich Mean Time, Zero degrees Easting's (longitude). It's a hypothetical line that runs from the north pole to the south,via Greenwich, London.

Answer 7

Greenwich mean time---the basis from which all clocks are set. Greenwich is on the prime meridian, everything--longitudes and also clocks, use that meridian as the starting point. maps are made and we are all east or west of it (unless you happen to live on the line itself--very few do), and time is "before" or "after" the clocks set at Greenwich.

Answer 8

Greenwich Mean Time

Answer 9

Just for FYI, military communications use GMT in their messages, called Zulu time.

Answer 10

it is the line around the earth for which the worlds time is based...ie if you are in the East you are -GMT and in the west +GMT...