Timezones

[Gargamel]

A while back, we were playing an online trivia game at lunch at work one day. We did it in team style, so we were pushing 100%. But when we got the answer wrong, per the game, I would usually be the one arguing why we were right. And after a bit of research, I was usually proven right.

This one question still bugs me. "How many time zones are there?" . The answer the were looking for was "24". Which is blatantly wrong. After a bit of arguing, I started the research. Not even google knows this answer. There are so many conflicting answers, I came up with anywhere between 72 and 115.

Found this wonderful little video tonight about how a programmer deals with timezones. Even if you're not a coder, you'll still enjoy it.

[GoldenRivet]

overthinking the issue i would say

traditionally speaking there are 24 time zones, each one consisting of 15 degrees, with each 15 degree interval representing one hour

i had this discussion with a friend of mine when we were in Midland, Texas earlier this year. He had noted that it was 7:00 in the morning, yet there was still very little daylight comparable to what he was used to seeing at 7:00 in the morning where he lived in Biloxi, Mississippi despite both areas being located in the central time zone

I explained to him that because the earth is spherical and we are located at nearly the westernmost extreme of the central time zone it would be dimmer there, and brighter in Biloxi because the sun is several degrees higher in the sky in Biloxi, Mississippi than it would be in Midland, Texas. I further explained to him that, depending on your location on the earth with respect to latitude, you would actually have to adjust your clock every few miles that you travel east or west and because of this it is actually closer to 6:15 am than 7:00am even though the clocks are all set to 7:00 am

not to make my friend sound stupid, because he is actually very intelligent, but this just goes to show that very few people actually think about it really.

the whole argument about the time change from standard to daylight savings time is invalid in my opinion, because (1) not all areas participate in the concept (2) the time change concept is a construct of man not nature and (3) time has been proven to vary depending both on gravitational density and speed and our time zone concept corrects for neither a moving clock or the variability of gravity from one place to another on the surface of the earth.

[Jimbuna]

^ Great explanatory post John

[Eichhörnchen]

I don't grasp this stuff too well, but you may be interested to know that the Greenwich Meridian line passes through my road just a few hundred yards away.

I once took my nephew (from the US) to see the marker and postulated that if he were to lay his wedding-tackle on the road, across the line, then he could go home and brag about having one so long that it could cross two time-zones.

[GoldenRivet]

Originally Posted by Eichhörnchen

if he were to lay his wedding-tackle on the road, across the line, then he could go home and brag about having one so long that it could cross two time-zones.

well done

[Sailor Steve]

"...and suddenly you have sixty-one seconds in a minute!"


You could have millions of "Time Zones" if you wanted, because when the center of the sun is directly above your exact line of latitude it's only a second away from not being there. Time Zones were created by the railroads to make it easier to say exactly when a train would be arriving. Arbitrary changes such as Daylight Savings Time change the time within the zone, but the zone itself does not change. Even going from before the IDL to behind it, while it may change the day, does not change the zone itself.

Sorry, for all the hilarity in that video, and seeing how whacky some of the lines can be, there are still only 24 time zones.

[Aktungbby]

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.

I love it that GMT (Greenwich Mean Time) is now 'ZULU' time...Talk about Mean: "I say George ol" chap, what's the hour?" "Why Paddy, I thinks it's Zulu Time Ol chum!...and we're about outta that! "

[Von Due]

Well, Aktungbby, consider:

Whisky time
Golf time
Papa time
Tango time

They wouldn't make it much clearer although whisky time doesn't sound so bad, really.

Originally Posted by Sailor Steve

...
Sorry, for all the hilarity in that video, and seeing how whacky some of the lines can be, there are still only 24 time zones.

Yes, and no:

North Korea, Newfoundland, India, Iran, Afghanistan, Burma, Sri Lanka, the Marquesas, as well as parts of Australia use half-hour deviations from standard time, and some nations, such as Nepal, and some provinces, such as the Chatham Islands of New Zealand, use quarter-hour deviations.

https://en.wikipedia.org/wiki/Time_zone

Any division into zones is arbitrary, and there are as many or as few as people agree to use for a specific purpose. And just to add to the confusion, take a look at this clock on the The Exchange building, Bristol. Two minute hands!


(From Wikipedia: https://en.wikipedia.org/wiki/The_Exchange,_Bristol "the red minute hand shows Greenwich Mean Time and the black minute hand shows Bristol time")

[Gargamel]

Time Zones are a political concept, not a geophysical one. Yes, there are 24 nicely segmented sections around the globe that describe the solar clock. But why not 48, or 96? When you start talking about solar noon, when the sun is directly overhead, then it changes the whole ball game. Then there are an infinite number of timezones. So therefore, governments had to decide what zone(s) their country would lie in, and what those lines would be.

Take a very isolated island country. If they lie near the trailing edge of a geophysical zone, then this tiny island is almost an hour behind the real time. Places like this, where there are no other neighbors to affect their time zone decisions, will often set their noon to be based upon when the sun is directly overhead.

IIRC, Indiana and Arizona don't follow DST, so they in fact jump time zones each spring and summer. Which in essence creates their own time zones that don't shift.

There are countries that are due north/south of each other that are not in the same timezone. Some have elected, for one reason or another, to be offset 15 or 30 minutes. Some are a hour different.

And then again with DST, countries in the northern and southern hemispheres jump in different directions on the same day, again creating different time zones.

When you look down on the globe from space, you don't see the borders between countries. Those are artificial political creations. The same applies to time zones.

UTC is a wonderful creation that helps coordinate times across the globe, especially when communicating with travelers abroad. (IE, Ships at sea, which most of us are familiar with, else we probably wouldn't be on this site!). But that's only 24 of the many time zones out there. On your computer, go to the adjust date/time setting, and look at the possible time zones you can choose from. There are six time zones alone that claim to be at UTC+11.

[Platapus]

It would depend on what one considers Time Zones.

To the military, there are 25 time zones. Alpha-India and Kilo-Zulu

Juliet, Juliet, where for art thou Juliet?

Almost interesting trivial answer....

Well although it is not universally known or recognized, but Juliette is right here. Juliet or Juliette or "J" is a designation for local time. It is not used much for obvious reasons, but when operations were more localized, 1200J meant local noon.

(http://www.worldtimezone.com/faq.html)

[mapuc]

I know it is divided into 24 zones (360 degrees/15 degrees for each timezone) but when I take a look on my telepage and watch the timezone-time it goes from my time and goes +1(Helsinki), +2 (Moscow) and so on until +11(Sydney) and +12 then it turn into -12, -11

Markus

[Rockstar]

Id wager not one you sea pups have ever picked up a sextant have ya? Ever read the American Practical Navigator? Probably couldnt navigate your way out of a wet paper sack.

If you had ever navigated by the stars you would understand why there are 24 timezones how they came to be and why they are lettered. Long before the advent of Google Maps and daylight savings time. Time zones were developed out of necessity in order locate ones longitudinal position. It was the likes of such great seafaring men as ship captain, astromoner and mathematician Nathaniel Bowditch who divided the world into the time zones by which to navigate. Politicians and the military had nothing to do with it.



Nathaniel Bowditch. March 26, 1773 – March 16, 1838