Why UTC is not a time zone

1
I'm often confused by the time-zones used in Astrodata-bank, which refers to British births in daylight saving time as GDT, rather than BST (British Summer time). I'm not sure what GDT stands for, but guess it's "Greenwich Daylight Time". The time zone for Ed Milliband is described as "MET h1e (is standard time)" - ?
I've also seen software give the time zone for British births that don't fall in periods of daylight saving as UTC, so this caught my eye today from Timeanddate.com:
http://www.timeanddate.com/time/gmt-utc-time.html
The Difference Between GMT and UTC

Greenwich Mean Time (GMT) is often interchanged or confused with Coordinated Universal Time (UTC). But GMT is a time zone and UTC is a time standard.
Although GMT and UTC practically share the same current time, there is a basic difference between the two:

?GMT is a time zone officially used in some European and African countries. The time can be displayed using both the 24-hour format (0 - 24) or the 12-hour format (1 - 12 am/pm).

?UTC is not a time zone, but a time standard that is the basis for civil time and time zones worldwide. This means that no country or territory officially use UTC as a local time.
So now you know.

4
Tom wrote:Thanks for that Deb. I've always wondered. Now can someone tell me why airline pilots refer to GMT as "Zulu Time?"
Blame the French.

The new Time standard is - UTC which is not the same as GMT- there can be a difference of 500 millisecs and this is important for- GPS/internet traffic.

The UTC then got referred by US Military and others as Z time and then called a Zulu time.(Zero degree longitude meridian time)

PD

(Papa Delta to Tango)

http://www.navy.mil/navydata/questions/zulutime.html
Prior to 1972, this time was called Greenwich Mean Time (GMT) but is now referred to as Coordinated Universal Time or Universal Time Coordinated (UTC). It is a coordinated time scale, maintained by the Bureau International des Poids et Mesures (BIPM). It is also known a "Z time" or "Zulu Time".

5
Yes I remember finding this out when I visited the Greenwich museum many years ago. Strictly speaking GMT no longer exists as the world default time since all International time zones are based on an atomic clock in Paris which establishes Universal Time from which all time zones are derived.

The French always resented the idea of International time being derived from Greenwich and delayed implementing times derived from it for decades after the rest of Europe. I guess having UT based from Paris is the final revenge!

http://en.wikipedia.org/wiki/Coordinated_Universal_Time

http://www.timeanddate.com/time/aboututc.html

http://en.wikipedia.org/wiki/Greenwich_Mean_Time

Mark
As thou conversest with the heavens, so instruct and inform thy minde according to the image of Divinity William Lilly

6
The French always resented the idea of International time being derived from Greenwich
The deal at the time was that the French adopted Greenwich as the meridian of reference and in return the English would adopt the metric system, never to keep their promise; or so are we told at school in the French-speaking part of Belgium.
I guess having UT based from Paris is the final revenge!
So Mark, I feel like you're right!

7
and in return the English would adopt the metric system, never to keep their promise
Well we did, but we never should have, dreadful system that it is. The traditional imperial system is loaded with astrological (and other) symbolic significance - for some details of which see Robin Heath's The Moon and Ancient Calendars - http://www.skyscript.co.uk/moonheath.html
So curious is this accurate connection between units of length and the astronomy of the sun and moon that I suggest, from the evidence presented here, that the origin of these units dates from at least four millenia ago in neolithic Europe. The earliest accurate observational astronomy presently known to us was based on the inch and the foot, whilst the Megalithic yard itself 'stored' the astronomical constants needed to marry the sun and moon into a useable calendar.
So, pah - we kept our promise, though we got sold short :)

8
Well we did
You're right. I was conforted in what I learned by my Taylor of Old Bond Street aftershave displaying proudly its weight in fluid ounces?actually I just discovered that all of my cosmetics offer both measures; be they French or English.
The traditional (?) system is loaded with (?) significance
Your sentence shortened (hopefully without too much of its meaning along), I agree with you to some point about it. I measure (in appropriate context) with my hands, from span to finger, and palm to phalanx in between. Or forearm with or without the hand when in need of a bigger scale. I think this participates in maintaining a worldview in which man is placed at the centre of what he experiences?being more than the observer of some objective measure. Just like astrologers see a solar return in a birthday.

Putting some soothing balm: most people still have Greenwich in mind.

9
Cedric wrote:
The deal at the time was that the French adopted Greenwich as the meridian of reference and in return the English would adopt the metric system, never to keep their promise; or so are we told at school in the French-speaking part of Belgium.
Sounds a little like a francocentric spin on the facts to me. Exactly, when are where was this ''deal'' agreed? Certainly not at the International Meridian Conference held in Washington D.C. in 1884.

The 7 resolutions of the 1884 Conference (see Link below) discuss a common meridian for transport and navigation but I dont see any reference to an agreement on a common measurement of distance.

http://www.thegreenwichmeridian.org/tgm ... article=10

It seems highly implausible to me that the two greatest powers in the late nineteenth century: The British Empire and the USA would voluntarily agree to abandon their adopted measurement systems for a European promoted one.

Britain only finally agreed to adopt the Metric system for weights and measures after joining the Common Market (EU of today) in 1973. But it took decades for this to take practical effect.

Even now we still calculate distances in miles and inches and people tend to describe their height in feet and inches.

Mark
As thou conversest with the heavens, so instruct and inform thy minde according to the image of Divinity William Lilly

10
My wife flies in a corporate jet all over the world. Her itineraries routinely refer to "Zulu Time." It's an American thing. I found this online:

"Zulu" time is that which you might know as "GMT" (Greenwich Mean Time). Our natural concept of time is linked to the rotation of the earth and we define the length of the day as the 24 hours it takes the earth to spin once on its axis.
As time pieces became more accurate and communication became global, there needed to be a point from which all other world times were based. Since Great Britain was the world's foremost maritime power when the concept of latitude and longitude came to be, the starting point for designating longitude was the "prime meridian" which is zero degrees and runs through the Royal Greenwich Observatory, in Greenwich, England, southeast of central London. As a result, when the concept of time zones was introduced, the "starting" point for calculating the different time zones was/is at the Royal Greenwich Observatory. When it is noon at the observatory, it is five hours earlier (under Standard Time) in Washington, D.C.; six hours earlier in Chicago; seven hours earlier in Denver; and, eight hours earlier in Los Angeles.
Unfortunately the Earth does not rotate at exactly a constant rate. Due to various scientific reasons and increased accuracy in measuring the earth's rotation, a new timescale, called Coordinated Universal Time (UTC), has been adopted and replaces the term GMT.
The Navy, as well as civil aviation, uses the letter "Z" (phonetically "Zulu") to refer to the time at the prime meridian. The U.S. time zones are Eastern ["R", "Romeo]; Central ["S", "Sierra"]; Mountain ["T", "Tango"]; Pacific ["U", "Uniform"]; Alaska ["V", "Victor"], and Hawaii ["W", "Whiskey"].
The Department of the Navy serves as the country's official timekeeper, with the Master Clock facility at the U.S. Naval Observatory, Washington, D.C. The correct time, at the time when you accessed this page, was: