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Thread: astronomy and the clock time vs sun time

  1. #1 astronomy and the clock time vs sun time 
    Join Date
    Jun 2009
    in summer here in europe we are 1 hour offset from the natural sun clock

    in winter two hours

    suns never up at noon

    thats to save light energy

    then why we are not offset 1 hour in winter and ZERO in summer

    why ALWAYS offset with natures time?

    i undesrtand change hours to save light, but one thing is change time and another being permanently offset

    if nobody provides a rational answer to this ill have to think this:

    industrial revolution period:

    mean guy a: hey how could we make the workers go to work much earlier without the sindicates complaining?

    mean guy b: hey i have an idea lets make them go to work at 7 am before the sun rises and tell them its 9 am

    anybody else have another theory on why the mechanical clock is always offset with the natural clock?

    i feel cheated into going to work at 7 am sun time and deceived into thinking its 9 am

    then the historical custom of starting work at 9 am has been twisted into starting to work at 7 am

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  3. #2  
    Join Date
    Jun 2009
    well its astronomy

    i thought of posting it in pseudo but i think i make some sense here


    sorry didnt notice there was an astronomy section where they can know better

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  4. #3  
    Moderator Moderator Janus's Avatar
    Join Date
    Jun 2007
    How much standard time varies from solar time depends on a couple of factor.

    For one, the Solar day (the time it takes between overhead meridian crossings) varies over the course of a year, So even if you set your watch to solar noon on a given day, it will drift in and out of sync with the Sun over the course of the year.
    Clocks are set to follow Mean solar time (the average length of a solar day) starting at noon when the Sun crosses the Meridian on the Vernal eqiunox.

    For another, It depends upon your location within your time zone. Clocks in a time zone are set to the meridian of the time zone. since time zone are ~1000 miles wide, if you are on the edge of one, your clock will be off off from the Sun by ~30 min even on the day of the vernal equinox. The only way to change that would be to use smaller time zones, which would be even more inconvenient.

    Putting all together, even if you lived at the edge of a time zone, the maximum your clock could be off from solar time is ~45 min not including daylight savings offset. (and that would be only on one day of the year, for the rest of the year it would be less. ).

    No conspiracy, just the fact that it is not possible to make all clocks match the Sun at all times.

    If it really bothers you so much to get up early by the Sun, I suggest you find a job that allows you to come in later or move so that you are on the edge of a time zone where the clock lags behind the Sun.
    "Men are apt to mistake the strength of their feelings for the strength of their argument.
    The heated mind resents the chill touch & relentless scrutiny of logic"-W.E. Gladstone

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  5. #4  
    Moderator Moderator Dishmaster's Avatar
    Join Date
    Apr 2008
    Heidelberg, Germany
    Just to make it clear: Daylight saving time adds one hour to the difference between zonal time and mean solar time in summer, not in winter. Here in Germany, the zonal time only agrees with the mean solar time at a longitude of 15 deg east, i.e. approximately along the city of Görlitz, far in the east of Germany.

    The time zones are a convention, and the zero point is just as arbitrary. In the beginning the zero meridian went through Paris. Later, it was moved to Greenwich, the location of the Royal Observatory in the UK. Time zones were invented at the advent of fast public transport via trains. At that time, each city had its own local time, which lead to a mess for the time tables of the trains. Therefore, it was agreed to define time zones so that the same time is valid for a region that is covered by a typical train ride. (see: Clark Blaise: Time Lord)

    The variation of the true local solar time vs. the mean solar time is a result of several things, mainly the eccentric orbit of the Earth around the Sun. According to the Kepler laws, the Earth moves more slowly at apogee (summer northern hemisphere, not exactly identical with the solstice) than at perigee (northern winter, currently around 5th January). The revolution around the Sun adds one solar day per year to the daily rotation of the Earth, but not at a constant rate. This is also called the equation of time.

    All these effects produce the phenomenon of the Analemma.
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