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Time and timekeeping



 
 
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  #11  
Old October 31st 17, 01:51 AM posted to sci.astro.amateur
palsing[_2_]
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Default Time and timekeeping

On Monday, October 30, 2017 at 3:38:34 PM UTC-7, Gerald Kelleher wrote:

I am sure this entertains those who know no better but if things were normal we would be discussing the real variations which arise as a separate surface rotation throughout the planet's orbit.


You mean, that separate surface rotation that explains the 366th sidereal rotation every year? Unfortunately, you just do not understand it at all, it is just another thing you need to unlearn...
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  #12  
Old October 31st 17, 08:02 AM posted to sci.astro.amateur
Gerald Kelleher
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Default Time and timekeeping

On Tuesday, October 31, 2017 at 12:47:02 AM UTC, palsing wrote:
On Friday, October 27, 2017 at 6:56:03 AM UTC-7, Gerald Kelleher wrote:

So much for correcting a reckless conclusion which tried to subvert the principles of the Lat/Long system with the nonsensical Ra/Dec format...


Tell us, Gerald, what exactly is 'nonsensical' about the Ra/Dec format?


Both the RA/Dec and Lat/Long timekeeping systems are outriggers of the calendar format which renders the natural 365 1/4 rotations per orbital circuit into a more manageable format of 1461 rotations for 4 annual circuits. The 24 hour weekday and its rotation of February 29th corrects the annual 6 hours worth of orbital distance that is dropped every orbit calculated on a 365 day cycle so after 4 cycles that amounts to one day and one rotation ( 6 hours* 4).

The Lat/Long system came first and is inextricably linked with the Equation of Time. It came first because it not only creates the average 24 hour day but also assigns a rate of rotation as 15 degrees per hour or 4 minutes for each degree of rotation. The amazing trick of converting 'average' to 'constant' allows the Lat/Long system designed around the Earth's geographic rotational traits to work with timekeeping and the basis of everything including the GPS system.

RA/Dec is an extension of the 24 hour system however rotation is already taken up with the Lat/Long system and the fact that one rotation is anchored to the sunrise/noon/sunset/ midnight cycle and especially the noon observation. It is impossible to justify RA/Dec in dynamical terms because it loses cause and effect between the weekday and rotation and that, for any person, is unforgivable as a concept.











It is essential for locating objects in the night sky, and in that regard, it is an essential tool for astronomers, both amateur and professional. Virtually everyone understands this very well, except, obviously, yourself. It has little, if anything, to do with timekeeping on Earth, and in no way is it attempting to "subvert the principles of the Lat/Long system"... now THAT notion is truly nonsensical!

It will take you many years to unlearn what you think you know about astronomy, for right now it is essentially nothing at all...


  #13  
Old October 31st 17, 08:10 PM posted to sci.astro.amateur
palsing[_2_]
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Default Time and timekeeping

On Tuesday, October 31, 2017 at 12:02:46 AM UTC-7, Gerald Kelleher wrote:

RA/Dec is an extension of the 24 hour system...


This just wrong in many ways, the RA/DEC system that we use is based on an extension of the Earth's axis of rotation, hence the name equatorial coordinate system. If we extend the Earth's axis outward into space, its intersection with the celestial sphere defines the north and south celestial poles; equidistant between them, and lying directly over the Earth's equator, is the celestial equator... I invite you to read this...

http://sbo.colorado.edu/SBO_OLD_SITE...ordinates.html

.... although I already know that you are incapable of actually learning something and will only respond with some rude statement that makes no sense....

It is impossible to justify RA/Dec in dynamical terms because it loses cause and effect between the weekday and rotation...


Well, of course it does, since its purpose has nothing to do with the solar day, but rather with the sidereal day, 2 very different things...

  #14  
Old November 1st 17, 08:02 AM posted to sci.astro.amateur
Gerald Kelleher
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Default Time and timekeeping

On Tuesday, October 31, 2017 at 7:10:10 PM UTC, palsing wrote:
On Tuesday, October 31, 2017 at 12:02:46 AM UTC-7, Gerald Kelleher wrote:

RA/Dec is an extension of the 24 hour system...


This just wrong in many ways, the RA/DEC system that we use is based on an extension of the Earth's axis of rotation, hence the name equatorial coordinate system.


I am afraid not Paul for the reason presented many times, the Lat/Long system required the construction of a meridian line to accurately determine the moment when the observer and his location were midpoint to the circle of illumination at noon. All observers along that meridian,irrespective of season or hemisphere, experience noon at the same time so the application of the Equation of Time rendered natural noon into 24 hour clock noon . If the observer was on a ship at sea he could then determine his location to any other meridian and any location on the planet as time difference equates to geographic separation.

The RA/Dec framework is homocentric as two sticks positioned in any direction will give you the same result so don't fool yourself into equating celestial sphere rotation with daily rotation,at least not directly.



If we extend the Earth's axis outward into space, its intersection with the celestial sphere defines the north and south celestial poles; equidistant between them, and lying directly over the Earth's equator, is the celestial equator... I invite you to read this...

http://sbo.colorado.edu/SBO_OLD_SITE...ordinates.html


Celestial sphere ideology is always the same, it assigns relevance to circumpolar motion and models the motions of the Earth on the assertions even though they defy experience. They don't even do this anymore as they conjured up a new proposal that the Earth turned 360 degrees in 24 hours but back in the year 1820 as the website Martin Brown referenced. When you begin with an error, it follows you through the centuries and in this case it was a failure to recognize with some conditions -

One 24 hour weekday equates to one 360 degree rotation
One year does not equate to one orbital period

A year can have 365 days/rotations in it or 366 days/rotations in it because the timekeeping term 'year' is drawn from the calendar framework. There is no external observation for 365 1/4 days/rotations per orbital circuit as the default or parent observation was always 1461 days/rotations to 4 orbital circuits.



... although I already know that you are incapable of actually learning something and will only respond with some rude statement that makes no sense....


Stop with the slogans and stock phrases, this is not sci.relativity.




It is impossible to justify RA/Dec in dynamical terms because it loses cause and effect between the weekday and rotation...


Well, of course it does, since its purpose has nothing to do with the solar day, but rather with the sidereal day, 2 very different things...


Ultimately you are being left behind by the new crowd who really are looking for ways to cut the ties between the 24 hour weekday and daily rotation through the hallucination of 'leap seconds'. The Precession of the Equinox is a further refinement of the original references which created the calendar framework based on the first seasonal appearance of a star from behind the glare of the central Sun.



  #15  
Old November 1st 17, 08:31 AM posted to sci.astro.amateur
palsing[_2_]
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Default Time and timekeeping

Sorry, Gerald, you are simply delusional about this. You really don't have a clue...
  #16  
Old November 1st 17, 09:14 AM posted to sci.astro.amateur
Gerald Kelleher
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Default Time and timekeeping

On Wednesday, November 1, 2017 at 7:31:11 AM UTC, palsing wrote:
Sorry, Gerald, you are simply delusional about this. You really don't have a clue...


You will probably have to accept that you are among the last to propose the 'solar vs sidereal' fiction as the people you look to for certainties have tried to change their story to 'leaps seconds' and an assertion that the Earth has been slowing down since the time of the dinosaurs to a idealized rotation once in 24 hours in the year 1820. The new proposal is a train to nowhere even if it buries humanity further into a clockwork framework with no reference to the motions of the planet whatsoever although it is designed for technological convenience.

I suppose there is always a rogue's satisfaction in perpetrating a scam at the expense of others but perhaps this particular one has gone on long enough. The greater satisfaction is in working with contemporary imaging and data and stacking these up to historical perceptions which have to be modified or adjusted to create genuine narratives of celestial structures, planetary motions, cause and effects between the Earth's motions and terrestrial sciences - things like that.








  #17  
Old November 1st 17, 12:06 PM posted to sci.astro.amateur
Martin Brown[_3_]
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Default Time and timekeeping

On 01/11/2017 07:02, Gerald Kelleher wrote:
On Tuesday, October 31, 2017 at 7:10:10 PM UTC, palsing wrote:
On Tuesday, October 31, 2017 at 12:02:46 AM UTC-7, Gerald Kelleher
wrote:

RA/Dec is an extension of the 24 hour system...


This just wrong in many ways, the RA/DEC system that we use is
based on an extension of the Earth's axis of rotation, hence the
name equatorial coordinate system.


I am afraid not Paul for the reason presented many times, the
Lat/Long system required the construction of a meridian line to
accurately determine the moment when the observer and his location
were midpoint to the circle of illumination at noon. All observers
along that meridian,irrespective of season or hemisphere, experience
noon at the same time so the application of the Equation of Time
rendered natural noon into 24 hour clock noon . If the observer was
on a ship at sea he could then determine his location to any other
meridian and any location on the planet as time difference equates to
geographic separation.


Until there was a reliable means to keep accurate mechanical time on
board ships observations of the sun were useless for determining
longitude. There were quirky ways promoted by the then Astronomer Royal
Neville Maskelyne that involved mutual events of Jupiters satellites or
the lunar distance method which he published in 1763. They were quite
difficult methods to use in practice though on a rolling ship.

https://en.wikipedia.org/wiki/Lunar_...ce_(navigation)

Even as late as the 1900's good marine chronometers for ocean going
navigation cost a significantly large sum of money. They have held their
value quite well too:

http://www.onlinegalleries.com/art-a...%20chronometer

direction will give you the same result so don't fool yourself into
equating celestial sphere rotation with daily rotation,at least not
directly.


Celestial sphere rotation of the fixed stars *is* a pure rotation.
(if you ignore nutation and precession)

The stars return to the same place in the sky as regular as clockwork.

It is the elliptical orbital motion of the Earth around the sun that
makes the solar motion across the sky vary in speed. And the moons
orbital motion around the Earth even more complicated. Something known
to the Babylonians and everyone educated since apart from you.

--
Regards,
Martin Brown
  #18  
Old November 1st 17, 01:40 PM posted to sci.astro.amateur
Gerald Kelleher
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Default Time and timekeeping

On Wednesday, November 1, 2017 at 11:06:47 AM UTC, Martin Brown wrote:



It is the elliptical orbital motion of the Earth around the sun that
makes the solar motion across the sky vary in speed.


Regards,
Martin Brown


This is the statement with the greatest impact in dynamical terms so no offence that I concentrate on this first. The variations in the natural noon cycle greater and lesser than the average 24 hour weekday also shares the same mechanism as seasonal changes.

The principles are based on variable orbital speed which in turn affects the surface rotation as a function of the orbital motion of the Earth. The Equation of Time which registers the natural inequality with each passage of a meridian to noon or midway either side of the circle of illumination (sunrise/sunset) is a global timekeeping correction so no hemispherical declination is involved as the application of the noon correction is common to along locations along a specific meridian line.

The only way to extract the inequality is to isolate the Polar day/night cycles at the poles and construct the Polar day/night cycle in isolation from the daily cycle. The Polar day/night cycle mirrors the daily cycle in terms of sunrise /sunset at the Equinoxes and noon/midnight at the Solstices. Currently the South pole is heading towards noon while the North pole is heading towards Polar midnight.

When the rotation responsible for the Polar day/night cycle is combined with daily rotation at our latitudes, the combination of these rotations create both the natural noon variations and the seasons. It is really lovely weather at the South Pole presently with the acknowledgment that the Sun will remain constantly in view until next March 21st as a means to isolate the polar cycle and the rotation behind it and also why the Equation of Time is necessary to isolate the average 24 hour day which in turn creates constant rotation as a neat trick -

https://www.usap.gov/videoclipsandmaps/spwebcam.cfm

There is no advantage in ignoring the Polar day/night cycle and the uneven rotation parallel to the orbital plane behind it.





  #19  
Old November 1st 17, 02:45 PM posted to sci.astro.amateur
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Default Time and timekeeping

On Wednesday, November 1, 2017 at 12:40:35 PM UTC, Gerald Kelleher wrote:
When the rotation responsible for the Polar day/night cycle is combined with daily rotation at our latitudes, the combination of these rotations create both the natural noon variations and the seasons.


This is wrong: the equation of time is not one sinusoid added to correct the time, it is two - one for the angle of the Earth's tilt (which is the one you say is responsible for polar day-night) and another one for the earth's elliptical orbit.
  #20  
Old November 1st 17, 03:14 PM posted to sci.astro.amateur
Chris L Peterson
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Default Time and timekeeping

On Wed, 1 Nov 2017 11:06:44 +0000, Martin Brown
wrote:

Until there was a reliable means to keep accurate mechanical time on
board ships observations of the sun were useless for determining
longitude...


It is interesting to read about the methods used by Lewis and Clark in
their journey across North America at the beginning of the 19th
century. The did have a chronometer, but had to reset it from time to
time. They did this using complex astronomical observations- the
distance between the Sun and Moon, or the positions of Jupiter's
moons.
 




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