sundials

Hi all

If you are interested by constructing your own sundial, you may be
interested by the web site www.shadowspro.com

It provides a freeware program to calculate plane sundials (any orientation
and inclination), analemmatic sundials and cylindrical sundals. They can be
built for any place in the world, including the southern hemisphere.
Sundials are printed full scale with all data needed to create a real
sundial. It is really simple to use.

In addition, you can simulate the shadow path on your sundial for a given
instant or in an animation. An astronomical ephemeris is also provided.

This program is provided in 8 languages, English, French, German, Italian,
Spanish, Portuguese, Dutch, Hungarian and comes with an extensive HTML
online help.

Come and visit the web site to see screen captures and view the list of
functions; and download the program.

Thanks
FB

"F B" wrote in message ...
Hi all

If you are interested by constructing your own sundial, you may be
interested by the web site www.shadowspro.com

It provides a freeware program to calculate plane sundials (any orientation
and inclination), analemmatic sundials and cylindrical sundals. They can be
built for any place in the world, including the southern hemisphere.
Sundials are printed full scale with all data needed to create a real
sundial. It is really simple to use.

In addition, you can simulate the shadow path on your sundial for a given
instant or in an animation. An astronomical ephemeris is also provided.

This program is provided in 8 languages, English, French, German, Italian,
Spanish, Portuguese, Dutch, Hungarian and comes with an extensive HTML
online help.

Come and visit the web site to see screen captures and view the list of
functions; and download the program.

Thanks
FB


Perhaps you can explain to participants here that it is necessary to
define the 24 hour day first via the axial rotation of the Earth and
this preceded the determination of the sidereal day by Flamsteed and
Huygens.You cannot figure out the sidereal value without first
defining a 24 hour clock day and somehow in the beginning of the 21 st
century,men have got lost as to what the Equation of Time does in
bridging the gap between the natural unequal day and the 24 hour clock
day.

You will find nobody here with the exception of myself who will agree
with you,those who maintain the axial rotation of the Earth through
360 degrees is 23 hours 56 min 04 sec insist that axial rotation is
determined by stellar circumpolar motion rather than the Sun based
reference of sundials,the EoT how the 24 hour clock emerges from the
difference between natural noon and clock noon or the difference
between the natural unequal day and the constant 24 hour clock day by
means of axial rotation.

"The earth makes a complete turn on its axis in 24 hours; it turns
therefore 360° in 24 hours or 15° each hour. If you were to stand on
one of the poles with a flat circular disk divided into sectors of
15°, you would be able to read the hour using the shadow of a vertical
rod placed through the centre of the disk. If you aligned the first
sector with the shadow cast by the Sun at its highest point overhead
at noon --the meridian--, then the shadow would cross the next sector
an hour later, and so on. The sector lines are thus hour lines."

Oriel36 wrote:

You will find nobody here with the exception of myself who will agree
with you,those who maintain the axial rotation of the Earth through
360 degrees is 23 hours 56 min 04 sec insist that axial rotation is
determined by stellar circumpolar motion rather than the Sun based
reference of sundials,the EoT how the 24 hour clock emerges from the
difference between natural noon and clock noon or the difference
between the natural unequal day and the constant 24 hour clock day by
means of axial rotation.

I wouldn't say "nobody". It's been a while since I worked with
time, but if I recall correctly, I believe that you are right
that the 24 hour day is solar based. The reasons, as you point
out are historical. I believe that originally time references
were set by a shaft in Greenwich used to measure noon. (sun position)
Today, of course, time standards are atomic based, but are still
corrected (leap seconds) for astronomical variations. Therefore
stellar circumpolar motion "time" is a variation of the solar
day rather than the other way around. Human inertia is a powerful
force.

bjacoby

--
Due to SPAM innundation above address is turned off!

wrote in message ...
Oriel36 wrote:

You will find nobody here with the exception of myself who will agree
with you,those who maintain the axial rotation of the Earth through
360 degrees is 23 hours 56 min 04 sec insist that axial rotation is
determined by stellar circumpolar motion rather than the Sun based
reference of sundials,the EoT how the 24 hour clock emerges from the
difference between natural noon and clock noon or the difference
between the natural unequal day and the constant 24 hour clock day by
means of axial rotation.

I wouldn't say "nobody". It's been a while since I worked with
time, but if I recall correctly, I believe that you are right
that the 24 hour day is solar based. The reasons, as you point
out are historical. I believe that originally time references
were set by a shaft in Greenwich used to measure noon. (sun position)
Today, of course, time standards are atomic based, but are still
corrected (leap seconds) for astronomical variations. Therefore
stellar circumpolar motion "time" is a variation of the solar
day rather than the other way around. Human inertia is a powerful
force.

bjacoby

The overall importance of the 24 hour/360 degree equivalency for axial
rotation and the Equation of Time computation by which this
equivalency is maintained really shows up in discriminating the
rotation of the local Milky Way stars and subsequently the changing
orientation of the remaining galaxies to foreground rotation.

By adopting the sidereal 'fixed stars' value for the rotation of the
Earth through 360 degrees,it creates a stellar circumpolar framework
and this makes it impossible to gauge the true nature of the changing
orientation of the remaining galaxies to local Milky Way reference
stars in their rotation around the galactic center.

Take the supernova in M81 for instance.

http://www.ast.cam.ac.uk/~ipswich/Ob...Ursa_Major.jpg

You may note that Polaris is at the top of the image,if those who are
so eager to retain stellar circumpolar motion for the axial rotation
of the Earth would wish to consider that using the difference between
observed supernova occurence and actual supernova occurance millions
of years ago the observed position of M81 to the local stars would
have changed.To note in which direction the orientation has changed it
is necessary to employ consideration of stellar rotation around the
Milky Way center and this means dropping the undisciplined 'every
valid point is the center' no boundary condition.

You will note that collection of supernova data as representative of
their parent galaxies are collected and treated on a celestial sphere
basis with no attempt made to condition the observances with the
effects of finite light distance and the difference between observed
position now and when the supernova actually occured in terms of their
position to local reference stars.

http://cfa-www.harvard.edu/cfa/ps/lists/Supernovae.html

There is no doubt that the subject material appears to be far removed
from Sundials and the EoT but it becomes rapidly complex when you
consider that the 3 known motions of the Earth,axial rotation,orbital
motion around the Sun and the Earth's motion around the galactic axis
is shortcircuited by contemporary views which maintain that the 'true'
rotation of the Earth is directly linked to stellar circumpolar
motion.In this respect,it is not a matter of proof or disproof but the
appeal and challenge of using the dormant foreground rotation to gauge
the actual structure and motion of galaxies to each other and to Milky
Way rotation.

In article ,
Oriel36 wrote:
By adopting the sidereal 'fixed stars' value for the rotation of the
Earth through 360 degrees,it creates a stellar circumpolar framework
and this makes it impossible to gauge the true nature of the changing
orientation of the remaining galaxies to local Milky Way reference
stars in their rotation around the galactic center.

You are aware, are you not, that astronomers use an inertial reference
frame based on the optical and radio postions of distance quasars, to
prevent just such errors?

And if you aren't aware of that, why haven't you paid attention when I
have told you this at least four times over the past year?

(Greg Hennessy) wrote in message ...
In article ,
Oriel36 wrote:
By adopting the sidereal 'fixed stars' value for the rotation of the
Earth through 360 degrees,it creates a stellar circumpolar framework
and this makes it impossible to gauge the true nature of the changing
orientation of the remaining galaxies to local Milky Way reference
stars in their rotation around the galactic center.

You are aware, are you not, that astronomers use an inertial reference
frame based on the optical and radio postions of distance quasars, to
prevent just such errors?


There is no constant displacement of .986 degrees for the orbital
motion of the Earth but this is what is used to justify the sidereal
value and axial rotation.

http://astrosun.tn.cornell.edu/cours...dereal_day.gif

The originator of this thread may be kind enough to explain to you
that Kepler's second law prohibits a constant positional orbital
displacement for each axial rotation of the Earth and apart from
cataloguing the position of celestial objects, directly linking the
Earth's rotation to stellar circumpolar motion is entirely idiotic.




And if you aren't aware of that, why haven't you paid attention when I
have told you this at least four times over the past year?

Never heard of you.

You are aware, are you not, that astronomers use an inertial reference
frame based on the optical and radio postions of distance quasars, to
prevent just such errors?


There is no constant displacement of .986 degrees for the orbital
motion of the Earth but this is what is used to justify the sidereal
value and axial rotation.

You are aware, are you not, that your reply has nothing to do with my
question? How about you answer my question?

And no one claims there is a "constant" displacement. There is an
average displacement though.

In article ,
(Oriel36) writes:

Perhaps you can explain to participants here that it is necessary to
define the 24 hour day first via the axial rotation of the Earth and
this preceded the determination of the sidereal day by Flamsteed and
Huygens.You cannot figure out the sidereal value without first
defining a 24 hour clock day and somehow in the beginning of the 21 st
century,men have got lost as to what the Equation of Time does in
bridging the gap between the natural unequal day and the 24 hour clock
day.

Make Simple Sun Dial:
http://members.aol.com/RichClark7/read/sundial.htm


The Mote around the Beam?
http://members.aol.com/RichClark7/read/mote.htm

Getting the Right Interpretation
http://members.aol.com/AVBibleTAB/av/interpre.htm

(Greg Hennessy) wrote in message ...
You are aware, are you not, that astronomers use an inertial reference
frame based on the optical and radio postions of distance quasars, to
prevent just such errors?


There is no constant displacement of .986 degrees for the orbital
motion of the Earth but this is what is used to justify the sidereal
value and axial rotation.

You are aware, are you not, that your reply has nothing to do with my
question? How about you answer my question?


Awareness is the faculty of recognising basic principles,in this case
the definition and distinction of the 24 hour day from the natural
unequal day using the Equation of Time and the Sun as a reference to
facilitate the seamless transition from one 24 hour day to the next
via axial rotation and the 24 hour/360 degree equivalency.

Adopt the sidereal view for the axial rotation of the Earth through
360 degrees and you are incorrect,you may not be aware of it but then
again the state of things is that dismal that half the references
relating to the development of clocks recogise the 24 hour/360 degree
equivalency while relativists only recognise the sidereal value.

It's all to do with how Newton defined the 24 hour clock day via the
EoT,ol boy.

"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." Principia



And no one claims there is a "constant" displacement. There is an
average displacement though.

Let's see you justify the sidereal value for the rotation of the Earth
through 360 degrees in astronomical terms.

http://astrosun2.astro.cornell.edu/a...dereal_day.gif

Naughty boys !,you should have listened to Newton when he told you
that there is no equable motion corresponding to axial rotation
through 360 degrees.

lexity (Richard Clark) wrote in message ...
In article ,
(Oriel36) writes:

Perhaps you can explain to participants here that it is necessary to
define the 24 hour day first via the axial rotation of the Earth and
this preceded the determination of the sidereal day by Flamsteed and
Huygens.You cannot figure out the sidereal value without first
defining a 24 hour clock day and somehow in the beginning of the 21 st
century,men have got lost as to what the Equation of Time does in
bridging the gap between the natural unequal day and the 24 hour clock
day.

Make Simple Sun Dial:
http://members.aol.com/RichClark7/read/sundial.htm


The Mote around the Beam?
http://members.aol.com/RichClark7/read/mote.htm

Getting the Right Interpretation
http://members.aol.com/AVBibleTAB/av/interpre.htm


As a Christian, there is nowhere nature is not and many here often
speak of "nature does'nt care" without realising that it is similar to
those who speak of God as though external to humanity.The fundamental
tenet of my Christian faith is the appreceation of God made man,not as
a choice foisted by accidents of birth,culture or geography but by
experience and in truth there is less need to preach out of what
amounts to common appreceation than any rules,laws and suchlike.So
often the 'laws of physics' and the 'laws of God' appeal to those who
find security in these things and I find no objection to them but
ultimately those who profess the importance of laws become
hypocrites,insincere and all those things which supplant the
connection between the infinite and the definite,the true aim to which
the study of nature or belief tends.

If nature is magnificant then it is also pitiless for again,there is
nowhere nature is not.Insofar as feebleminded men have adhered to a
particular set of physical 'laws' which are incorrect at a very basic
level they can neither speak of its magnificense nor how low it makes
them appear,all they can do is congratulate themselves.

When men begin to appreceate rather than teach then there is true
belief and true science.