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Equation of Time - does it correct for speed of light?



 
 
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  #1  
Old September 3rd 03, 06:24 AM
cgbusch
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Posts: n/a
Default Equation of Time - does it correct for speed of light?

Because of Earth's elliptical orbit, the planet varies its distance from the Sun.

(From http://science.msfc.nasa.gov/headlin...ast04jan_1.htm)
"perihelion both hemispheres were 147.5 million km from the Sun."
"152.6 million km in July, which astronomers call aphelion"
A difference of 5.1 million km.

the speed of light = 299 792 458 m / s

(5100000000 m)/(299792458 m/s)=17.01 seconds

How much variance would this introduce in the EoT? Would this
difference add up to an appreciable amount?
--
CB
  #2  
Old September 3rd 03, 12:33 PM
Jeff Root
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Default Equation of Time - does it correct for speed of light?

"cgbusch" asked:

Subject: Equation of Time - does it correct for speed of light?

Because of Earth's elliptical orbit, the planet varies its
distance from the Sun.

(From http://science.msfc.nasa.gov/headlin...ast04jan_1.htm)
"perihelion both hemispheres were 147.5 million km from the Sun."
"152.6 million km in July, which astronomers call aphelion"
A difference of 5.1 million km.

the speed of light = 299 792 458 m / s

(5100000000 m)/(299792458 m/s)=17.01 seconds

How much variance would this introduce in the EoT? Would this
difference add up to an appreciable amount?


You can answer those questions yourself, by answering these
questions:

How does the speed of light affect the time of noon? How would
the time of noon be affected if light were so fast that it went
from Sun to Earth in 1/100 of a second? How would the time of
noon be affected if light were so slow that it went from Sun to
Earth in 100 days?

-- Jeff, in Minneapolis

..
  #3  
Old September 3rd 03, 09:05 PM
George Dishman
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Posts: n/a
Default Equation of Time - does it correct for speed of light?


"cgbusch" wrote in message om...
Because of Earth's elliptical orbit, the planet varies its distance from the Sun.

(From http://science.msfc.nasa.gov/headlin...ast04jan_1.htm)
"perihelion both hemispheres were 147.5 million km from the Sun."
"152.6 million km in July, which astronomers call aphelion"
A difference of 5.1 million km.

the speed of light = 299 792 458 m / s

(5100000000 m)/(299792458 m/s)=17.01 seconds

How much variance would this introduce in the EoT? Would this
difference add up to an appreciable amount?


I make it +/- 23 milliseconds.

Paul Schlyter already answered this but maybe you missed it.
I don't know if you are familiar with stellar aberration, my
apologies if you already know this. If you point a telescope
at a star at some time of the year and again six months later,
you find you need to change the angle slightly. In the
heliocentric frame, the Earth is moving so you have to tilt
the telescope slightly to avoid the light hitting the sides
as in this diagram

http://physwww.mcmaster.ca/~kingb/2C...aberration.jpg

from these notes

http://physwww.mcmaster.ca/~kingb/2C...Lecture_3.html

It should be clear that the angle only depends on the speed
of the telescope relative to the star. For the same reason
it affects the angle of the shadow cast by the gnomon by the
same amount.

If you think of it from a geocentric perspective, the light we
see was emitted from the Sun roughly 500s earlier and the Sun
will have moved in that time. The error in position obviously
depends on the time taken and that depends on the distance,
but the angle by which the apparent location of the Sun is
displaced is independent of the distance since it depends on
the ratio of the error to the distance.

The speed of the Earth in orbit varies from 29.29km/s to
30.29km/s so by my calculations the aberration angle varies
from 20.15 to 20.84 arcseconds. The mean is 20.50 but remember
the EoT tells you the difference between true noon when the Sun
actually appears due south and noon based on mean time. If the
orbit of the Earth were circular, the constant 20.5 arcsec
offset would be incorporated in mean time so there would be no
contribution to the EoT. It is therefore only the variation we
need to consider. That is just +/-0.34 arc seconds and the Earth
rotates that much in 23 milliseconds.

If you compare the variation of 0.34 with the angular diameter
of the Sun of about 1900 arcsec, it means the error is 5000
times less than the width of the Sun's shadow from a fine wire
gnomon.

The rotation of the Earth subtracts 0.464km/s * cos(latitude)
from the orbital motion but again that is constant for any given
location so obviously doesn't affect the EoT.

The mean aberration angle means that the Sun appears to be due
south about 1.366 seconds before that alignment actually occurs,
reduced to 1.353s at my latitude of 51N by the Earth's rotation.
Compare that wit the 2 minutes plus it takes the Sun to cross
the meridian.

HTH
George


  #4  
Old September 4th 03, 01:49 PM
Jeff Root
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Posts: n/a
Default Equation of Time - does it correct for speed of light?

"cgbusch" replied to Jeff Root:

How much variance would this introduce in the EoT?
Would this difference add up to an appreciable amount?


You can answer those questions yourself, by answering these
questions:

How does the speed of light affect the time of noon?

That is my question!


You asked how *much* it would affect the time of noon.
I asked *how* it would affect the time of noon. My question
must be answered before it is possible to even try to answer
your question.

How would the time of noon be affected if light were so fast
that it went from Sun to Earth in 1/100 of a second? How would
the time of noon be affected if light were so slow that it went
from Sun to Earth in 100 days?

But it is not constant.


True, of course. I attempted to simplify my reply. The fact
of the variation is essential to your question but completely
irrelevant to my answer. I would have done better to make up
a different set of hypothetical values, such as:

How would the time of noon be affected if the speed of light
were 1 billion km/s? How would the time of noon be affected
if the speed of light were 10 km/s?

It varies up to 17.01 seconds, so the Earth has more time to
rotate. Effectively, the EoT takes variable solar days and makes
them uniform 24 hour days. Let's say on 1 "end" of Earth's orbit
the light got to Earth in 1/100 of a second and at the other "end",
it took 8,640,000 seconds.


Unless I just don't understand what you are saying, this
doesn't make much sense. I wonder if you misunderstood my
hypothetical scenarios? Given that the speed of light is
constant (in vacuum), you are apparently describing an
extremely elliptical orbit. I was setting up two separate
scenarios: One with a very high value of c; the other with
a very low value of c.

In the 1/100s case, the Earth would get to rotate 4.16e-5 degrees,
while at the larger distance, it would get to rotate 36000 degrees.

But I know it is not that simple.

As the Earth moves away from the Sun it takes longer for the light
to reach it and as the Earth moves towards the Sun it can take up
to 17 seconds less.


Those statements are correct in both your scenario and mine,
but they are *almost* irrelevent in both your scenario and mine.
George pointed out that the finite speed of light causes the
very tiny change in angle called the aberration of starlight.
With a sufficiently low value of c, the aberration would become
significant in the equation of time.

However, the Sun is continually lit, so this all could be moot.


That was my point.

I failed to think of the aberration of starlight because its
effect with the real value of c is so miniscule as to be totally
irrelevant. Aberration of sunlight cannot be measured because
the edge of the Sun is too fuzzy to measure its position with
the required precision. Only extremely careful measurements
of star positions with very good instruments over long time
intervals revealed the aberration.

(Although for an observer on Mars observing Earth (because of
Earth's distinctive features) it would have an effect on the
Martian spying on noon in Washington DC - although perhaps just
the light lag from Earth to Mars only...)


Yes, this is equivalent to how the speed of light was first
measured, by timing the eclipses of Jupiter's moons.

-- Jeff, in Minneapolis

..
  #5  
Old September 4th 03, 01:59 PM
Oriel36
external usenet poster
 
Posts: n/a
Default Equation of Time - does it correct for speed of light?

"George Dishman" wrote in message ...
"cgbusch" wrote in message om...
Because of Earth's elliptical orbit, the planet varies its distance from the Sun.

(From http://science.msfc.nasa.gov/headlin...ast04jan_1.htm)
"perihelion both hemispheres were 147.5 million km from the Sun."
"152.6 million km in July, which astronomers call aphelion"
A difference of 5.1 million km.

the speed of light = 299 792 458 m / s

(5100000000 m)/(299792458 m/s)=17.01 seconds

How much variance would this introduce in the EoT? Would this
difference add up to an appreciable amount?


I make it +/- 23 milliseconds.

Paul Schlyter already answered this but maybe you missed it.
I don't know if you are familiar with stellar aberration, my
apologies if you already know this. If you point a telescope
at a star at some time of the year and again six months later,
you find you need to change the angle slightly.


Geocentric

In the
heliocentric frame, the Earth is moving so you have to tilt
the telescope slightly to avoid the light hitting the sides
as in this diagram


Still geocentric.
http://physwww.mcmaster.ca/~kingb/2C...aberration.jpg

from these notes

http://physwww.mcmaster.ca/~kingb/2C...Lecture_3.html


Roemer was Danish,he does'nt even get the first sentence right,Roemer
did'nt determine the speed of Light,Roemer determined the Equation of
Light.

http://dibinst.mit.edu/BURNDY/Online...mer/index.html


It should be clear that the angle only depends on the speed
of the telescope relative to the star. For the same reason
it affects the angle of the shadow cast by the gnomon by the
same amount.


"Speed of telescope" means nothing unless the poster is a monkey,next
sentence makes less sense.


If you think of it from a geocentric perspective, the light we
see was emitted from the Sun roughly 500s earlier and the Sun
will have moved in that time.


Geocentric perspective/relative space


The error in position obviously
depends on the time taken and that depends on the distance,


There are no errors in relative motion.


but the angle by which the apparent location of the Sun is
displaced is independent of the distance since it depends on
the ratio of the error to the distance.


"Ratio of error" has no meaning in the English language or any other.






The speed of the Earth in orbit varies from 29.29km/s to
30.29km/s so by my calculations the aberration angle varies
from 20.15 to 20.84 arcseconds. The mean is 20.50 but remember
the EoT tells you the difference between true noon when the Sun
actually appears due south and noon based on mean time.


The EoT is the mathematical computation which reduces the inequality
of daily longitudinal alignments to a constant alignment based on a 24
hour day/clock rather than a natural day which generates inequal
alignments.The old chestnut to "remember" is actually a pathetic
attempt to ask you to forget that relativists,the whole damn lot of
them did'nt know that Newton was expressing the difference between
absolute time and relative time as the EoT. Removing absolute time was
removing one half of the Equation of Time,mean time specifically.



If the
orbit of the Earth were circular, the constant 20.5 arcsec
offset would be incorporated in mean time so there would be no
contribution to the EoT.


If the Earth's orbit were circular there would be no EoT,there would
only be the slight variation the poster brings up.


It is therefore only the variation we
need to consider. That is just +/-0.34 arc seconds and the Earth
rotates that much in 23 milliseconds.

If you compare the variation of 0.34 with the angular diameter
of the Sun of about 1900 arcsec, it means the error is 5000
times less than the width of the Sun's shadow from a fine wire
gnomon.

The rotation of the Earth subtracts 0.464km/s * cos(latitude)
from the orbital motion but again that is constant for any given
location so obviously doesn't affect the EoT.

The mean aberration angle means that the Sun appears to be due
south about 1.366 seconds before that alignment actually occurs,
reduced to 1.353s at my latitude of 51N by the Earth's rotation.


Funny,funny,funny,along any line of longitude from North to South pole
it will be noon,noon means longitudinal alignment be you at 30
degrees,50 degrees,80 degrees along that longitudinal line.


Compare that wit the 2 minutes plus it takes the Sun to cross
the meridian.

HTH
George


You insulted the guy even if he does'nt know it.
  #6  
Old September 5th 03, 12:11 AM
Oriel36
external usenet poster
 
Posts: n/a
Default Equation of Time - does it correct for speed of light?

"George Dishman" wrote in message ...
"Oriel36" wrote in message om...
"George Dishman" wrote in message ...
"cgbusch" wrote in message om...

How much variance would this introduce in the EoT? Would this
difference add up to an appreciable amount?

I make it +/- 23 milliseconds.


snip: no content

Gerald, you haven't attempted to show an error in my calculation, nor
have you offered a derivation of your own. Since you won't be able to
do that without first learning how to apply Kepler's Laws to the Earth,
I suggest you instead reply to the outstanding thread with the somewhat
misleading subject "sundial & Earth's tilt questions".

You said I couldn't depict the EoT on the figures so I have done that.
If you now understand what they are showing, I will put back Figure 2
and you can comment on the point of the thread.

http://www.dishman.me.uk/George/SolarDay/index.htm

In case you have trouble finding the article, here is the recent content:

Dishman" wrote in message ...
"Oriel36" wrote in message om...

...
Noon is the alignment of a longitude meridian with the Sun and at any
given location on the planet from pole to pole this alignment takes
place.


Fine, and if you look at figures 1 and 3, you will see that the
blue line representing the Greenwich Meridian is pointing at the
Sun. This is (natural) noon on these days.

As the Earth axially rotates to face the Sun and repeats the
alignment you find that the second drawing in your website does not
reflect the inequality but sundials do.


a) The second drawing does not depict noon in any way. This is
_intentional_.

b) The series of drawing is _not_ intended to depict the inequality
of natural days. I have told you that several times yet you still
make the same error. If anything illustrates incompetence it is
your inability to take onboard what I have said repeatedly.

Your diagrams and especially the third diagram leaves no room to put
the Equation of Time correction ...


Looking first at figure 1, on Nov. 3 2003, the EoT has a value
of 16m 26s and the Sun is ahead of mean time. The figure shows
the meridian aligned with the Sun so that is natural noon. If
the Sun is ahead of mean time, it is not yet noon by GMT so we
have to subtract the 16m 26s. That means a clock on the wall
of the Greenwich Observatory would show 11:43:34 when the Sun
was due south on the 3rd.

Do you agree so far?

Now looking at figure 3, note that the EoT correction is also
16m 26s on the 4th Nov 2003. The same calculation applies so
the clock on the wall would show 11:43:34 when the Sun was due
south on the 4th as well. That means that from figure 1 to
figure 3 is a change of exactly 24 hours.

If you follow that and agree I haven't made any mistakes in the
calculations, I will next talk about figure 2.


George


George

If you ever decide to put a figure 3 in your graphics,be sure to show
the alignments without applying the Equation of Time and then you will
know why Newton (and you) is correct and why Mach was an idiot
followed by the spacetime guy.

If you have'nt figured out that absolute time is one half of the Eot
correction here it is.



"Absolute time, in astronomy, is distinguished from relative, by the
equation or correlation of the vulgar time. For the natural days are
truly unequal, though they are commonly considered as equal and used
for a measure of time; astronomers correct this inequality for their
more accurate deducing of the celestial motions. It may be, that there
is no such thing as an equable motion, whereby time may be accurately
measured. All motions may be accelerated and retarded, but the true,
or equable, progress of absolute time is liable to no change. The
duration or perseverance of the existence of things remains the same,
whether the motions are swift or slow, or none at all: and therefore,
it ought to be distinguished from what are only sensible measures
thereof; and out of which we collect it, by means of the astronomical
equation.... Absolute, true, and mathematical time, of itself, and
from its own nature flows equably without regard to anything external,
and by another name is called duration: relative, apparent, and common
time, is some sensible and external (whether accurate or unequable)
measure of duration by the means of motion, which is commonly used
instead of true time; such as an hour, a day, a month, a year."
  #7  
Old September 5th 03, 07:50 AM
Paul Schlyter
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Posts: n/a
Default Equation of Time - does it correct for speed of light?

In article ,
George Dishman wrote:

"Jeff Root" wrote in message m...
"cgbusch" replied to Jeff Root:

It varies up to 17.01 seconds, so the Earth has more time to
rotate. Effectively, the EoT takes variable solar days and makes
them uniform 24 hour days. Let's say on 1 "end" of Earth's orbit
the light got to Earth in 1/100 of a second and at the other "end",
it took 8,640,000 seconds.


Unless I just don't understand what you are saying, this
doesn't make much sense. I wonder if you misunderstood my
hypothetical scenarios? Given that the speed of light is
constant (in vacuum), you are apparently describing an
extremely elliptical orbit.


It is just the difference between the time of flight at
perihelion and aphelion, 490s compared to 508s but that
is so small the orbit is close to circular.


THe difference in light time doesn't matter to the apparent
position! Why? Well, suppose the distance doubles -- then
the light time delay doubles too, and the object is able to
move twice as far during the light time delay. But since
the distance has doubled, this corresponds to the same
change in _apparent_ distance during the light time delay.
Therefore the light time delay doesn't matter.

What matters is the velocity of the moving object, relative
to the observer: the faster the object moves, the greater
the apparent change in position during the light time delay,
and this apparent change in position will be v/c radians,
where v is the speed of the object relative to the observer,
and c is the speed of light.

--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://www.stjarnhimlen.se/
http://home.tiscali.se/pausch/
  #8  
Old September 5th 03, 03:20 PM
George Dishman
external usenet poster
 
Posts: n/a
Default Equation of Time - does it correct for speed of light?


"Paul Schlyter" wrote in message ...
In article ,
George Dishman wrote:

"Jeff Root" wrote in message m...
"cgbusch" replied to Jeff Root:

It varies up to 17.01 seconds, so the Earth has more time to
rotate. Effectively, the EoT takes variable solar days and makes
them uniform 24 hour days. Let's say on 1 "end" of Earth's orbit
the light got to Earth in 1/100 of a second and at the other "end",
it took 8,640,000 seconds.

Unless I just don't understand what you are saying, this
doesn't make much sense. I wonder if you misunderstood my
hypothetical scenarios? Given that the speed of light is
constant (in vacuum), you are apparently describing an
extremely elliptical orbit.


It is just the difference between the time of flight at
perihelion and aphelion, 490s compared to 508s but that
is so small the orbit is close to circular.


THe difference in light time doesn't matter to the apparent
position!


I know, I said so in
and

The above comment was purely about the eccentricity of the
Earth's orbit.

Why? Well, suppose the distance doubles -- then
the light time delay doubles too, and the object is able to
move twice as far during the light time delay. But since
the distance has doubled, this corresponds to the same
change in _apparent_ distance during the light time delay.
Therefore the light time delay doesn't matter.

What matters is the velocity of the moving object, relative
to the observer: the faster the object moves, the greater
the apparent change in position during the light time delay,
and this apparent change in position will be v/c radians,
where v is the speed of the object relative to the observer,
and c is the speed of light.


It is easiest to see in heliocentric inertial coordinates.
What matters is the direction from which the light arrives.
The light that hits the sundial at noon was emitted a little
over 8 minutes earlier but since the Sun is unmoving it
still comes from the same direction regardless of when it
was emitted.

I think cgbusch is visualising the situation in geocentric
co-rotating coordinates and the explanation is less obvious
then. I'm sure you will know it Paul but it might be
instructive for some other posters to consider it. ;-)

best regards
George


  #9  
Old September 5th 03, 11:32 PM
George Dishman
external usenet poster
 
Posts: n/a
Default Equation of Time - does it correct for speed of light?


"Oriel36" wrote in message
om...
"George Dishman" wrote in message

...
"Oriel36" wrote in message

om...
"George Dishman" wrote in message

...
"Oriel36" wrote in message

om...
"George Dishman" wrote in message

...

You said I couldn't depict the EoT on the figures so I have done

that.
If you now understand what they are showing, I will put back Figure

2
and you can comment on the point of the thread.

http://www.dishman.me.uk/George/SolarDay/index.htm

In case you have trouble finding the article, here is the recent

content:

Dishman" wrote in message

...
"Oriel36" wrote in message

om...
...
Noon is the alignment of a longitude meridian with the Sun and

at any
given location on the planet from pole to pole this alignment

takes
place.

Fine, and if you look at figures 1 and 3, you will see that the
blue line representing the Greenwich Meridian is pointing at the
Sun. This is (natural) noon on these days.

As the Earth axially rotates to face the Sun and repeats the
alignment you find that the second drawing in your website does

not
reflect the inequality but sundials do.

a) The second drawing does not depict noon in any way. This is
_intentional_.

b) The series of drawing is _not_ intended to depict the

inequality
of natural days. I have told you that several times yet you

still
make the same error. If anything illustrates incompetence it is
your inability to take onboard what I have said repeatedly.

Your diagrams and especially the third diagram leaves no room to

put
the Equation of Time correction ...


Looking first at figure 1, on Nov. 3 2003, the EoT has a value
of 16m 26s and the Sun is ahead of mean time. The figure shows
the meridian aligned with the Sun so that is natural noon. If
the Sun is ahead of mean time, it is not yet noon by GMT so we
have to subtract the 16m 26s. That means a clock on the wall
of the Greenwich Observatory would show 11:43:34 when the Sun
was due south on the 3rd.

Do you agree so far?

Now looking at figure 3, note that the EoT correction is also
16m 26s on the 4th Nov 2003. The same calculation applies so
the clock on the wall would show 11:43:34 when the Sun was due
south on the 4th as well. That means that from figure 1 to
figure 3 is a change of exactly 24 hours.

If you follow that and agree I haven't made any mistakes in the
calculations, I will next talk about figure 2.

George

George

If you ever decide to put a figure 3 in your graphics,


Gerald, if you ever decide to read the page, you will find
figure 3 is already there (it is figure 2 that is omitted
as stated above).

be sure to show
the alignments without applying the Equation of Time


Gerald, if you ever decide to read the page, you will find
that is what was already done (as stated above).

I suggest you try looking at the page _before_ criticising
it to avoid further embarrassment.

Now try to understand, the two diagrams on the page should
_not_ be contentious. The aim is to lay down something
simple we can agree before adding in the bit that will
probably cause a disagreement. Please look again and see
if I have addressed your concerns, then we can actually
start to have a conversation. Remember these are _not_
intended to be an explanation of the EoT, the purpose is
quite different as you will see when we can move on.


All you have to do is show the Earth's alignment with the Sun(Noon) in
terms of absolute time as distinct from showing it with the EoT
applied and then you overturn a century's worth of ignorance.I do not
particularily like the way Newton phrased the EoT but it is easy to
understand where he is coming from.

The matter can be expressed,in fact it begs expression in basic
English but your diagrams will suffice when you include the Earth's
alignment with the Sun in terms of a 24 hour clock,call it mean
time,absolute time,clock time or whatever,the definition given by
Newton will make sense and more importantly it cannot be tampered
with.


Gerald, I still get the impression you haven't
looked at the figures since I updated them. You are
still asking me to do something that is already done.

http://www.dishman.me.uk/George/SolarDay/index.htm

Figure 3 shows an alignment _exactly_ 24 hours after
that in figure 1. Both alignments are _precisely_ the
natural noon for that day. To achieve that, I had to
use one of four particular days in the year but we
can use the fact that the rotation of the Earth is
constant to apply any conclusion to other days via
the EoT since it deals with the variation of the
natural day.

So have you any complaints about those figures or can
you agree that:

a) Figure 1 shows the noon alignment on the 3rd Nov.

b) Figure 3 shows the noon alignment on the 4th Nov.

c) The Sun appears due south at 11:43:34 on both days.

d) The figures are separated by exactly 24 hours.

If you disagree, please say specifically what you think
the error is. If not, please say you agree and we can
move on.

George


  #10  
Old September 6th 03, 02:32 AM
Oriel36
external usenet poster
 
Posts: n/a
Default Equation of Time - does it correct for speed of light?

"George Dishman" wrote in message ...
"Oriel36" wrote in message
om...
"George Dishman" wrote in message

...
"Oriel36" wrote in message

om...
"George Dishman" wrote in message

...
"Oriel36" wrote in message

om...
"George Dishman" wrote in message

...

You said I couldn't depict the EoT on the figures so I have done

that.
If you now understand what they are showing, I will put back Figure

2
and you can comment on the point of the thread.

http://www.dishman.me.uk/George/SolarDay/index.htm

In case you have trouble finding the article, here is the recent

content:

Dishman" wrote in message

...
"Oriel36" wrote in message

om...
...
Noon is the alignment of a longitude meridian with the Sun and

at any
given location on the planet from pole to pole this alignment

takes
place.

Fine, and if you look at figures 1 and 3, you will see that the
blue line representing the Greenwich Meridian is pointing at the
Sun. This is (natural) noon on these days.

As the Earth axially rotates to face the Sun and repeats the
alignment you find that the second drawing in your website does

not
reflect the inequality but sundials do.

a) The second drawing does not depict noon in any way. This is
_intentional_.

b) The series of drawing is _not_ intended to depict the

inequality
of natural days. I have told you that several times yet you

still
make the same error. If anything illustrates incompetence it is
your inability to take onboard what I have said repeatedly.

Your diagrams and especially the third diagram leaves no room to

put
the Equation of Time correction ...


Looking first at figure 1, on Nov. 3 2003, the EoT has a value
of 16m 26s and the Sun is ahead of mean time. The figure shows
the meridian aligned with the Sun so that is natural noon. If
the Sun is ahead of mean time, it is not yet noon by GMT so we
have to subtract the 16m 26s. That means a clock on the wall
of the Greenwich Observatory would show 11:43:34 when the Sun
was due south on the 3rd.

Do you agree so far?

Now looking at figure 3, note that the EoT correction is also
16m 26s on the 4th Nov 2003. The same calculation applies so
the clock on the wall would show 11:43:34 when the Sun was due
south on the 4th as well. That means that from figure 1 to
figure 3 is a change of exactly 24 hours.

If you follow that and agree I haven't made any mistakes in the
calculations, I will next talk about figure 2.

George

George

If you ever decide to put a figure 3 in your graphics,

Gerald, if you ever decide to read the page, you will find
figure 3 is already there (it is figure 2 that is omitted
as stated above).

be sure to show
the alignments without applying the Equation of Time

Gerald, if you ever decide to read the page, you will find
that is what was already done (as stated above).

I suggest you try looking at the page _before_ criticising
it to avoid further embarrassment.

Now try to understand, the two diagrams on the page should
_not_ be contentious. The aim is to lay down something
simple we can agree before adding in the bit that will
probably cause a disagreement. Please look again and see
if I have addressed your concerns, then we can actually
start to have a conversation. Remember these are _not_
intended to be an explanation of the EoT, the purpose is
quite different as you will see when we can move on.


All you have to do is show the Earth's alignment with the Sun(Noon) in
terms of absolute time as distinct from showing it with the EoT
applied and then you overturn a century's worth of ignorance.I do not
particularily like the way Newton phrased the EoT but it is easy to
understand where he is coming from.

The matter can be expressed,in fact it begs expression in basic
English but your diagrams will suffice when you include the Earth's
alignment with the Sun in terms of a 24 hour clock,call it mean
time,absolute time,clock time or whatever,the definition given by
Newton will make sense and more importantly it cannot be tampered
with.


Gerald, I still get the impression you haven't
looked at the figures since I updated them. You are
still asking me to do something that is already done.

http://www.dishman.me.uk/George/SolarDay/index.htm

Figure 3 shows an alignment _exactly_ 24 hours after
that in figure 1. Both alignments are _precisely_ the
natural noon for that day. To achieve that, I had to
use one of four particular days in the year but we
can use the fact that the rotation of the Earth is
constant to apply any conclusion to other days via
the EoT since it deals with the variation of the
natural day.

So have you any complaints about those figures or can
you agree that:

a) Figure 1 shows the noon alignment on the 3rd Nov.

b) Figure 3 shows the noon alignment on the 4th Nov.

c) The Sun appears due south at 11:43:34 on both days.

d) The figures are separated by exactly 24 hours.

If you disagree, please say specifically what you think
the error is. If not, please say you agree and we can
move on.

George


George

I am flying out tommorrow and I will take the oppurtunity to thank you
and especially in having to unearth a history that you will never see
discussed.As much of this history is based on your great maritime
nation of Britain I have to admire how they worked the sidereal method
in with the EoT so that if noon or the alignment of the Earth with the
Sun was lost for that day,they had a fallback.

Now all that appears certain is that your early 20th century mentors
had'nt the foggiest notion of the EoT and this is what Newton was
presenting in terms of the difference between absolute time and
relative time,they can be forgiven for they simply did'nt know but you
do now,to defend these spacetime concepts which never made sense
anyway you become a traitor so instead of applying your obvious
intelligence and the genuine groundwork you've done towards
rectifying things you find yourself in the same position as
Einstein,knowing that his isolation of the Mercury does'nt work but
unable to undo the damage.

Until last week I did'nt know exactly whether the mariners corrected
the clock to noon or applied the correction at noon because the
procedure is lost to history but then you see these practical men
adopting the best possible methods of the EoT and the sidereal methods
and by this means you can develop a great love and admiration for
human endeavor.You will of course snip what you need to but that is
fine,you have to live with the destruction of part of your heritage
both as a national and more importantly scientifically.

"The log was kept in ship's time, that is, the local apparent time,
adjusted at intervals to the change of longitude: and by old practice
an adjustment was made at noon, when the officer taking the latitude
sight called "Twelve o'clock, Sir," and the Captain said "Make it so,"
(though the actual observations for local time were necessarily made
morning and afternoon). If it were necessary to establish the accurate
time of an event we should have to enquire more particularly whether
the time of the nautical day was on that ship carried on from the noon
on which it began, or adjusted to the noon on which it ended, or
perhaps altered during the night from one to the other, as is more or
less the present practice in merchant ships, though H.M. Navy keeps
Standard Time. In default of better information we may without serious
error (in days of sail) take the recorded hour as in the apparent time
of the meridian of longitude mentioned in the account, and for form's
sake apply the equation of time to reduce to civil time of the
meridian"

There is not one single thread in any of the sci.forums that is more
important than this one,that you choose to remain and turf it out is a
credit to you,that you choose to direct the original poster towards
relativity ruins what you could have done or still can do.
 




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