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Xibalba
2012-Oct-07, 06:41 PM
Hi, I don't really know how to call this, but I want to know if it exists :

A clock that, instead of being based on the time zones, would be based on a 360° separation of the Earth. Like wherever you are on Earth, it is noon the moment the sun is at its zenith. Or, instead of having 24 separate time zones, it has 360 or more.

Does a clock, an app or a software like that exists?

Hornblower
2012-Oct-07, 06:48 PM
Hi, I don't really know how to call this, but I want to know if it exists :

A clock that, instead of being based on the time zones, would be based on a 360° separation of the Earth. Like wherever you are on Earth, it is noon the moment the sun is at its zenith. Or, instead of having 24 separate time zones, it has 360 or more.

Does a clock, an app or a software like that exists?Do you mean a clock that will automatically reset itself to local mean solar time if you move with it?

Xibalba
2012-Oct-07, 06:56 PM
Do you mean a clock that will automatically reset itself to local mean solar time if you move with it?

Yes, relying on the geographical coordinates.

Centaur
2012-Oct-07, 07:14 PM
Does a clock, an app or a software like that exists?

Yes, it's called a sundial and that "app" has existed for a very long time. ;)

Strange
2012-Oct-07, 07:15 PM
Hi, I don't really know how to call this

A sundial ?

grapes
2012-Oct-07, 07:24 PM
Like wherever you are on Earth, it is noon the moment the sun is at its zenith.

And remember, the sun is not usually at its highest at noon, local mean solar time!

Xibalba
2012-Oct-07, 08:14 PM
Yes, it's called a sundial and that "app" has existed for a very long time. ;)

It is close, but a sundial also starts and stops with the rise and set of the sun. That also means that near the poles, you whether have a very long time to check the clock, or no time at all, depending on the latitude and the time of the year.

What I'm looking for is a clock that takes the position of the sun, the position of the Earth (the center of the Earth, probalby) and your position compared to those. Then, independant of your latitude, but depending on your longitude coordinates, give you the exact time of your location depending on the sun.

Why?

Because there are time zones which make no sense, and when you live close to a frontier between two time zones, the sun for you might set at 8PM, but will set at 7PM for your western neighbour, and that makes no sense. With a "longitudinal clock" or something like this, such aberrations won't happen, except maybe a difference of a few hundredths of a second.

Xibalba
2012-Oct-07, 08:14 PM
And remember, the sun is not usually at its highest at noon, local mean solar time!

Isn't it always on its daily highest?

Centaur
2012-Oct-07, 08:42 PM
Isn't it always on its daily highest?

Of course the Sun is only at zenith when directly overhead. You seem to be referring to the time that the Sun transits your local meridian, which is local true noon. The daily separations for this event are not exactly 24 mean hours due to the equation of time factors. Culmination (highest altitude) occurs very close to the time of meridian transit, but not precisely due to the Sun’s continuous change in declination.

Any app that provides the solar hour angle is what you want. The hour angle can be expressed in hours or degrees. At local true noon the solar hour angle is 00:00 hr or 0°. Six true hours earlier it was -06:00 hr or -90°. Six true hours after true noon it will be +06:00 hr or +90°. At local true midnight the solar hour angle is ±12:00 hr or ±180°.

Xibalba
2012-Oct-07, 08:56 PM
Of course the Sun is only at zenith when directly overhead. You seem to be referring to the time that the Sun crosses your local meridian, which is local true noon. The daily separations for this event are not exactly 24 mean hours due to the equation of time factors. Culmination (highest altitude) occurs very close to the time of meridian passage, but not precisely due to the Sun’s continuous change in declination.

Any app that provides the solar hour angle is what you want. The hour angle can be expressed in hours or degrees. At local true noon the solar hour angle is 00:00 hr or 0°. Six true hours earlier it was -06:00 hr or -90°. Six true hours later it will be +06:00 hr or +90°. At local true midnight the solar hour angle is ±12:00 hr or ±180°.

Yes, that's what I'm seeking, and of course the length of a day wouldn't be exactly 24 hours, and would be slightly out of time, more every year, until every leap year. Surely this exists, but what must I look for?

Centaur
2012-Oct-07, 09:14 PM
Yes, that's what I'm seeking, and of course the length of a day wouldn't be exactly 24 hours, and would be slightly out of time, more every year, until every leap year. Surely this exists, but what must I look for?

It would not be more out of time each year, and leap years have nothing to do with this matter. The daily deviations are based on the equation of time, which is the sum of an annual cycle and a semiannual cycle: http://en.wikipedia.org/wiki/Equation_of_time

I assume that the solar hour angle is available as output with many apps, but I cannot name them. I can easily obtain the hour angle with my self-made software, but that is not publicly distributed.

Centaur
2012-Oct-07, 09:53 PM
The solar hour angle is your local sidereal time minus the Sun’s right ascension. True local time (sundial time, not mean time) differs from the solar hour angle by twelve hours. True local time is also your local standard (not daylight savings) time, plus four minutes multiplied by the number of degrees you are east of the central meridian of your time zone, plus the equation of time.

grapes
2012-Oct-07, 11:58 PM
Why?

Because there are time zones which make no sense, and when you live close to a frontier between two time zones, the sun for you might set at 8PM, but will set at 7PM for your western neighbour, and that makes no sense. With a "longitudinal clock" or something like this, such aberrations won't happen, except maybe a difference of a few hundredths of a second.
Chicago and Mobile would both be on the "88 degrees west" clock, but the sun set tonight in Chicago at 6:21pm, while it set in Mobile at 6:30pm. That's mostly because of their 11 degree difference in latitude.

Xibalba
2012-Oct-08, 12:15 AM
Chicago and Mobile would both be on the "88 degrees west" clock, but the sun set tonight in Chicago at 6:21pm, while it set in Mobile at 6:30pm. That's mostly because of their 11 degree difference in latitude.

Yes, but the sun will also rise sooner at Chicago than at Mobile, by about 9 minutes I guess... And yes, that is because of the latitude. However, I don't want a latitude-longitude clock that will display 6 AM when the sun rises, and 6 PM when the sun sets, meaning the hours will pass much faster during the winter days and slower in the winter nights, and vice-versa for summer.

But man, 11 degrees of difference? That's pretty big. It's not like it was your neighbour.

Centaur
2012-Oct-08, 01:00 AM
Yes, but the sun will also rise sooner at Chicago than at Mobile, by about 9 minutes I guess...


Actually, tomorrow the Sun will rise 5 minutes later for Chicago than Mobile. But as you note, that is moot regarding your concern. I already showed you two ways of calculating what you want. And as I suggested, I imagine there are apps that calculate at least the solar hour angle for you, but I can't name any.

Hornblower
2012-Oct-08, 01:31 AM
With today's ultraminature electronic gadgetry, it should be technically straightforward to build a GPS-based position finder that would automatically reset a clock to keep local mean solar time as the clock is moved. It might even be possible to build it into a wristwatch. Whether or not there might be a market for it, one can only guess.

About 20 years ago I heard of a gizmo some entrepeneur was advertising as a placebo for jet lag. It was a programmable watch with inputs for the departure and arrival times and longitudes. If set properly it would keep a pretty good approximation of local solar time throughout a long flight. The advertising claim was that it would prevent or at least diminish the symptoms of jet lag by eliminating obvious time changes during the journey. It seemed like a dubious claim to me, and I never heard anything more about it.

grapes
2012-Oct-08, 02:16 AM
Yes, but the sun will also rise sooner at Chicago than at Mobile, by about 9 minutes I guess...
No, apparently it rises *later* by four minutes.

I was using the website www.timeanddate.com


But man, 11 degrees of difference? That's pretty big. It's not like it was your neighbour.
I see now, you're only concerned about confusion between close neighbors. Still, the confusion mostly exists at the boundaries--a one degree-wide time zone is four minutes wide, so there'd be a difference of four minutes (not hundredths of a second) between neighbors, and there would be fifteen times as many borders. Mean local time is certainly a handy concept, for those who understand the concept, but it would be difficult to implement across all human activity.

Xibalba
2012-Oct-08, 02:44 AM
No, apparently it rises *later* by four minutes.

I was using the website www.timeanddate.com

I see now, you're only concerned about confusion between close neighbors. Still, the confusion mostly exists at the boundaries--a one degree-wide time zone is four minutes wide, so there'd be a difference of four minutes (not hundredths of a second) between neighbors, and there would be fifteen times as many borders. Mean local time is certainly a handy concept, for those who understand the concept, but it would be difficult to implement across all human activity.

I was wrong about the sun setting, it was only a guess. But this does not change the fact that I don't care about the sunrise/set time lag between two different cities, in fact, my post is not about this difference, but about getting the real time depending on the sun's, Earth's and one's position on it.

Imagine it's like making a new time zone map, and instead of separating it into 24 hours (I know there are more time zones than that, but you see where I'm going), we would separate the world into 360 degrees, or even more, separating it by seconds or hundredths of seconds.

Xibalba
2012-Oct-08, 02:46 AM
No, apparently it rises *later* by four minutes.

I was using the website www.timeanddate.com

I see now, you're only concerned about confusion between close neighbors. Still, the confusion mostly exists at the boundaries--a one degree-wide time zone is four minutes wide, so there'd be a difference of four minutes (not hundredths of a second) between neighbors, and there would be fifteen times as many borders. Mean local time is certainly a handy concept, for those who understand the concept, but it would be difficult to implement across all human activity.

I was wrong about the sun setting, it was only a guess. But this does not change the fact that I don't care about the sunrise/set time lag between two different cities, in fact, my post is not about this difference, but about getting the real time depending on the sun's, Earth's and one's position on it.

Imagine it's like making a new time zone map, and instead of separating it into 24 hours (I know there are more time zones than that, but you see where I'm going), we would separate the world into 360 degrees, or even more, separating it by seconds or hundredths of seconds.

grapes
2012-Oct-08, 03:04 AM
Imagine it's like making a new time zone map, and instead of separating it into 24 hours (I know there are more time zones than that, but you see where I'm going), we would separate the world into 360 degrees, or even more, separating it by seconds or hundredths of seconds.Those are arcseconds? Or even hundredths of arcseconds?

Xibalba
2012-Oct-08, 03:23 AM
Those are arcseconds? Or even hundredths of arcseconds?

I couldn't tell you with certainty, but I guess I am talking about the same minutes and seconds (or hundredths of seconds) the GPS will tell you when it gives you coordinates. I GUESS it is arcseconds, since it's on a sphere.

grapes
2012-Oct-08, 04:29 AM
I couldn't tell you with certainty, but I guess I am talking about the same minutes and seconds (or hundredths of seconds) the GPS will tell you when it gives you coordinates. I GUESS it is arcseconds, since it's on a sphere.
That's what I thought, seconds (and hundredths) of latitude and longitude.

A second of latitude (or longitude) is less than 31.4 meters, and a hundredth of that is less than the distance from your left hand to your right hand when your arms are hanging down at your sides.

Centaur
2012-Oct-08, 05:13 AM
Imagine it's like making a new time zone map, and instead of separating it into 24 hours (I know there are more time zones than that, but you see where I'm going), we would separate the world into 360 degrees, or even more, separating it by seconds or hundredths of seconds.

Well you’ve described the system in use prior to 1883. Each town was its own time zone with clocks calibrated to local true noon. That was great until the inventions of the telegraph and railroad. It’s impractical in the modern world with instant communication and speedy transportation. It was the railroads that first began using standard times zones in 1883 to avoid the confusion created by having to adjust watches and schedules for each station.

An international conference in 1884 agreed to use the mean solar time at the meridian of Greenwich as be the standard upon which all other time zones would be based. Of course most zones differed from Greenwich by an integer number of hours. In a few cases there was an additional half hour. By 1895 almost all US states adhered to standard zones. It was made federal law in 1918.

You’re desired clock could be built, but I doubt that there is enough interest to make it economically viable. In my case I’d prefer going in the opposite direction: Place the whole world on Universal (Greenwich) Time to eliminate still remaining confusion. That's what's done in air traffic control where the slightest confusion regarding time could lead to tragedy.

Xibalba
2012-Oct-08, 01:42 PM
That's what I thought, seconds (and hundredths) of latitude and longitude.

A second of latitude (or longitude) is less than 31.4 meters, and a hundredth of that is less than the distance from your left hand to your right hand when your arms are hanging down at your sides.

Thanks, I did not know how many meters was a longitudinal degree. Hundredths of degrees won't be necessary then :)


Well you’ve described the system in use prior to 1883. Each town was its own time zone with clocks calibrated to local true noon. That was great until the inventions of the telegraph and railroad. It’s impractical in the modern world with instant communication and speedy transportation. It was the railroads that first began using standard times zones in 1883 to avoid the confusion created by having to adjust watches and schedules for each station.

An international conference in 1884 agreed to use the mean solar time at the meridian of Greenwich as be the standard upon which all other time zones would be based. Of course most zones differed from Greenwich by an integer number of hours. In a few cases there was an additional half hour. By 1895 almost all US states adhered to standard zones. It was made federal law in 1918.

You’re desired clock could be built, but I doubt that there is enough interest to make it economically viable. In my case I’d prefer going in the opposite direction: Place the whole world on Universal (Greenwich) Time to eliminate still remaining confusion. That's what's done in air traffic control where the slightest confusion regarding time could lead to tragedy.

Thanks for the answer. I also think we should all concentrate our efforts to all live in the same time zone. But this kind of clock might be useful for certain occasions, and under certain perspectives. For example, during a long flight you usually get jet lag, but with this app or software you can keep track of the local true time and, for example, sleep in the correct hours of the local time. When you arrive at destination, you have the local time.