Astronomical coordinates

JRS: In article , dated Thu,
12 Jan 2006 23:30:50 local, seen in news:sci.astro, Jonathan Silverlight
posted :
In message , Dr John Stockton
writes

Since the Astronomical Unit is defined as the *mean* distance between
earth and sun,
...

A bit of rummaging around on the Web shows that the definition is a lot
more complex than that. This seems typical
" the radius of an unperturbed circular orbit a massless body would
revolve about the sun in 2*(pi)/k days (i.e., 365.2568983.... days),
where k is defined as the Gaussian constant exactly equal to
0.01720209895." http://neo.jpl.nasa.gov/glossary/au.html

That's not even grammatical, at least in our language.

Diverted to a group more suited to rational discussion, and accompanied
by a suggestion for ST that FAQ W.18 might possibly be modified to give
or point to the current authoritative international standard definitions
(if there be such).

Does/should the Light Year depend on the Tropical Year or the
SI/Gregorian one?

Is the AU *defined* as 149 597 870 660 000 metres, with "mean
separation" being merely icing on the cake - or /vice versa/? In other
words, can new radar work change that number, or is it now as fixed as
299 792 458 m/s is?

--
© John Stockton, Surrey, UK. Turnpike v4.00 MIME. ©
Web URL:http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms & links;
Astro stuff via astron-1.htm, gravity0.htm ; quotings.htm, pascal.htm, etc.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.

http://neo.jpl.nasa.gov/glossary/au.html

At least some guys stand a chance of breaking out of that audacious
maneuver of Newton in converting Flamsteed's 1461 day
calendrical/celestial sphere average for axial rotation to a
geocentric/heliocentric orbital equivalency,this one -

"That the fixed stars being at rest, the periodic times of the five
primary planets, and (whether of the sun about the earth, or) of the
earth about the sun, are in the sesquiplicate proportion of their mean
distances from the sun." Newton

http://members.tripod.com/~gravitee/phaenomena.htm

Even I was impressed,at least for a while,at the way Newton converted
the distance along the circumference of an orbit to stretching of
orbital distances based on the sidereal average.You get the right
answer working off mean Sun/Earth distances however you cannot fit the
..986 degree orbital displacement into an elliptical framework at retain
Keplerian motion.

Do you not think that the Earth travelling faster at the aphelion is
pretty ugly even if you seemingly get the correct answer for stretching
and diminishing orbital distances .It was not a bad attempt and to be
fair,he was consistent in his misconduct or misjudgement.

People are too impressed with mindnumbing significant digits and leave
the celestial images,motions and orientations too soon.They can make
more informed judgements on what exactly went wrong and where with
just a little more attension to the details of the origins of
Copernican heliocentricity before making the leap to Keplerian
refinements.

In message , Dr John Stockton
writes
JRS: In article , dated Thu,
12 Jan 2006 23:30:50 local, seen in news:sci.astro, Jonathan Silverlight
posted :
In message , Dr John Stockton
writes

Since the Astronomical Unit is defined as the *mean* distance between
earth and sun,
...

A bit of rummaging around on the Web shows that the definition is a lot
more complex than that. This seems typical
" the radius of an unperturbed circular orbit a massless body would
revolve about the sun in 2*(pi)/k days (i.e., 365.2568983.... days),
where k is defined as the Gaussian constant exactly equal to
0.01720209895." http://neo.jpl.nasa.gov/glossary/au.html

That's not even grammatical, at least in our language.

Well, "our language" is NASAspeak there :-)

Diverted to a group more suited to rational discussion, and accompanied
by a suggestion for ST that FAQ W.18 might possibly be modified to give
or point to the current authoritative international standard definitions
(if there be such).

Does/should the Light Year depend on the Tropical Year or the
SI/Gregorian one?

Is the AU *defined* as 149 597 870 660 000 metres, with "mean
separation" being merely icing on the cake - or /vice versa/? In other
words, can new radar work change that number, or is it now as fixed as
299 792 458 m/s is?

This site seems to have the answers to your questions
http://www.vt-2004.org/Background/Infol2/EIS-G3.html
The AU is derived and its value may change.
The year is the Julian year.

At the accuracy that most distances measured in light years are known. I'm
surprised that it matters which 'year' is used. I'd also be surprised if a
light year is not a defined distance rather than calculated from c. and and
an earth year, and therefore subject to revision at each redefinition of
those units. 'Light years', though a perfectly good unit, are a basically
amateur unit, anyway. Professionals tend to use parsecs (Another geocentric
unit!)

Roger

Proffessional bluffers !, at the level of Newton's
geocentric/heliocentric orbital equivalency (quasi-geocentricity) which
generates the mean Sun/Earth distances and subsequently the AU,the
details of Newton's misjudgements can be handled comfotably in respect
to Keplerian motion.Converting an axial rotational coordinate of .986
deg/3 min 56 sec to an orbital displacement is breathtaking in its
audacity however tranfering the differential from mean distances
through the center of a planet's orbit to mean Sun/Earth distances and
then on to orbital stretching is truly a remarkable exercise* .It
effectively wipes out the principles of Copernican heliocentricity and
its later Keplerian/Roemerian refinements.

If anyone can condone the Newtonian manner in which observed planetary
motions are resolved they can believe in anything they want hence the
contemporary undisciplined help-yourself-to-a-theory
opinions.Professional ditherers relying on definitions is hardly
astronomy,at least the amateurs will show you pretty pictures and has
some benefits. !.






"PHENOMENON V.
Then the primary planets, by radii drawn to the earth, describe areas
no wise proportional to the times; but that the areas which they
describe by radii drawn to the sun are proportional to the times of
description.

For to the earth they appear sometimes direct, sometimes stationary,
nay, and sometimes retrograde. But from the sun they are always seen
direct, and to proceed with a motion nearly uniform, that is to say, a
little swifter in the perihelion and a little slower in the aphelion
distances, so as to maintain an equality in the description of the
areas. This a noted proposition among astronomers, and particularly
demonstrable in Jupiter, from the eclipses of his satellites; by the
help of which eclipses, as we have said, the heliocentric longitudes of
that planet, and its distances from the sun, are determined."

http://members.tripod.com/~gravitee/phaenomena.htm

You talk rubbish and you can't spell. Go back to school......

oriel36 wrote:
Proffessional bluffers !, at the level of Newton's
geocentric/heliocentric orbital equivalency (quasi-geocentricity) which
generates the mean Sun/Earth distances and subsequently the AU,the
details of Newton's misjudgements can be handled comfotably in respect
to Keplerian motion.Converting an axial rotational coordinate of .986
deg/3 min 56 sec to an orbital displacement is breathtaking in its
audacity however tranfering the differential from mean distances
through the center of a planet's orbit to mean Sun/Earth distances and
then on to orbital stretching is truly a remarkable exercise* .It
effectively wipes out the principles of Copernican heliocentricity and
its later Keplerian/Roemerian refinements.

If anyone can condone the Newtonian manner in which observed planetary
motions are resolved they can believe in anything they want hence the
contemporary undisciplined help-yourself-to-a-theory
opinions.Professional ditherers relying on definitions is hardly
astronomy,at least the amateurs will show you pretty pictures and has
some benefits. !.






"PHENOMENON V.
Then the primary planets, by radii drawn to the earth, describe areas
no wise proportional to the times; but that the areas which they
describe by radii drawn to the sun are proportional to the times of
description.

For to the earth they appear sometimes direct, sometimes stationary,
nay, and sometimes retrograde. But from the sun they are always seen
direct, and to proceed with a motion nearly uniform, that is to say, a
little swifter in the perihelion and a little slower in the aphelion
distances, so as to maintain an equality in the description of the
areas. This a noted proposition among astronomers, and particularly
demonstrable in Jupiter, from the eclipses of his satellites; by the
help of which eclipses, as we have said, the heliocentric longitudes of
that planet, and its distances from the sun, are determined."

http://members.tripod.com/~gravitee/phaenomena.htm

In message , L
writes
You talk rubbish and you can't spell. Go back to school......

Please don't respond to GK. It's a piece of Artificial Stupidity that
only posts the same old script because someone takes the bait.

It is too difficult to tell whether your justifications are inhuman or
subhuman,the idea that the Earth has a variable axial tilt to the
Sun/orbital plane would be a joke if it were not that it is the
majority view -

http://www.diduknow.info/sun/images/high_low_sun.gif

http://imagine.gsfc.nasa.gov/docs/as...s/980116c.html

You poor creatures, following after Flamsteed and Newton, mistake the
changing daylight/darkness asymmetry for the Total length of a day
represented by the Equation of Time.

http://www.pfm.howard.edu/astronomy/...S/AACHCIR0.JPG

I assure you that while parts of Newton's ballistic agenda can be
salvaged absolutely nothing remains of the astronomical format built
around the sidereal justification .At least Newton was consistent in
his misjudgements or misconduct and especially in the way he shifted
an axial cordinate to an orbital coordinate to generate his mean
Sun/Earth distances.He got his correct answer for Keplerian elliptical
geometry alright but you can't fit a .986 degree orbital displacement
in an elliptical framework and get Keplerian motion.

Squirm all you will,you live with an error so basic that it would be a
joke in the era of Galileo and Kepler.