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Daylight Saving Time



 
 
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  #11  
Old November 4th 17, 02:33 PM posted to sci.astro.amateur
Gerald Kelleher
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Default Daylight Saving Time

On Saturday, November 4, 2017 at 11:52:00 AM UTC, Mike Collins wrote:
Gerald Kelleher wrote:
It seems that playing fast and loose with the English language or even
torturing it comes at a price as followers of the early 20th century
theorists have lost the capacity to put the back and forth motions of the
planets and satellites around the parent Sun or parent planet using the
normal language of motion to the left or to the right.

The rule of thumb is that a planet or a satellite, as we see it from
Earth, moves from left to right in front of the parent object and from
right to left as it travels behind it. This restores context after to
losing it to RA/Dec modelling.


Except in the Southern Hemisphere. Herodotus knew this and described it in
his account of the voyages of Phoenicians



Very simple rule to understand and use the analogy to support it.

Jupiter's satellites move from their widest point to the right of the planet as they pass in front of their parent and move from right to left as they moves behind the planet -

https://www.youtube.com/watch?v=zqZEgoJasPQ&t=21s

With notable exceptions, the inner planets process the same motions as they move from left to right in front of the Sun and from right to left as they turn in behind the Sun -

http://www.popastro.com/images/plane...ary%202012.jpg

I would love to show time lapse but only sequential imaging exists presently.


The Sun is stationary and central however the language of left/right can be used to describe the motions of the other planets and satellites or even the proof of the Earth's orbital motion where a star transitions from an evening to a morning appearance, not that the Earth moves parallel to the orbital plane but the Earth does. This alone accounts for the direct/retrograde motion of the faster moving Venus and Mercury and joins the separate perspective of direct/retrogrades of the slower moving planets seen from Earth.

  #12  
Old November 4th 17, 03:20 PM posted to sci.astro.amateur
Chris L Peterson
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Default Daylight Saving Time

On Fri, 3 Nov 2017 22:40:37 -0700 (PDT), RichA
wrote:

Daylight saving is garbage and should be done away with. It's not 1880 and we aren't all frigging farmers.


Farmers don't care what the clock says. They operate on solar time.
Daylight saving time was about saving energy for city dwellers. Maybe
it does, maybe it doesn't; I've seen different analyses. But they all
conclude that any actual savings is small indeed, and most recent
studies show that the disruption the change causes (in both
directions) is economically harmful as well as hard on human health.
It's a stupid thing to maintain.
  #13  
Old November 5th 17, 10:52 AM posted to sci.astro.amateur
Gerald Kelleher
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Posts: 1,551
Default Daylight Saving Time

The initial application of DST has a jarring effect on the rhythms of the body in the same way jet lag has so, in terms of chronobiology, it is worthwhile studying the motions of the Earth via astronomy or using the body clocks to put the motions of the Earth in order.

The reason the 24 hour day and rotation of the leap correction doesn't register is that our bodies are tuned to the daily cycle. Each year there is an approximate loss of 6 hours in orbital distance between the timekeeping format of 365 days/rotations and the true proportion of 365 1/4 rotations per orbital circuit. After four cycles of 365 days, we catch up with the true framework by applying a 24 hour cycle which the body clock is accustomed to so we don't feel the leap day correction.

There is no exact fit between the proportions of rotations for 4 orbital circuits and timekeeping and it is the discrepancy that surfaces as the Precession of the Equinoxes insofar as the original references for the timekeeping framework is based on a first annual appearance of a star.

  #14  
Old November 7th 17, 01:47 PM posted to sci.astro.amateur
Martin Brown[_3_]
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Default Daylight Saving Time

On 04/11/2017 14:20, Chris L Peterson wrote:
On Fri, 3 Nov 2017 22:40:37 -0700 (PDT), RichA
wrote:

Daylight saving is garbage and should be done away with. It's not 1880 and we aren't all frigging farmers.


Farmers don't care what the clock says. They operate on solar time.


Indeed and these days the big combines even in the UK have powerful
lights so that they can operate 24/7 or until the dew becomes a problem.

Daylight saving time was about saving energy for city dwellers. Maybe
it does, maybe it doesn't; I've seen different analyses. But they all
conclude that any actual savings is small indeed, and most recent
studies show that the disruption the change causes (in both
directions) is economically harmful as well as hard on human health.
It's a stupid thing to maintain.


I think it does make a useful difference at higher latitudes like the UK
where long light summer nights are helpful in getting things done after
work. UK at latitude 50+ has winter daylight ~8h and in summer ~17h the
extra light in the evening is useful to most people.

At low latitudes the seasonal variation in daylength is less pronounced.

--
Regards,
Martin Brown
 




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