Re: The Physics Behind 'Contractions'.

On Sun, 04 Jan 2009 20:41:33 +0100, "Paul B. Andersen"
<paul.b.andersen@xxxxxxxxxxxxxxx> wrote:

Dr. Henri Wilson wrote:
On Sat, 03 Jan 2009 21:11:55 +0100, "Paul B. Andersen"
<paul.b.andersen@xxxxxxxxxxxxxxx> wrote:

Not so. At 10 LYs the angle is about 0.3"
And at 100 LYs the angle is about 0.03".
Try to measure the offset of a circle with radius several
minutes of arc, where the offset is in the same order or less
than the resolution of the telescope!

The problem is the same no matter how parallax is measured.

And what's more, your method 'works' (not really) only for
stars close to the ecliptic pole, and you would use a year
to measure those few stars with a precision much less than
what could be done with the traditional method.

Well, six months should be enough.

For stars away from the ecliptic pole point the telescope at one that is very
distant and rotate the telescope around ONLY its barrel axis. In other words
the telescope remains orientated absolutely the same throughout the year but
the observer is upside down after six months. Aberration is then always in the
same direction for all the stars in the viewing area. The whole field also
remains the same except for individual parallax ellipses.

s
\ \
\ \
\ \
\ \
\ \
\ \
\ \
\ \
___.___orbit plane

Sorry, but the idea is ridiculous. :-)

You persistently say my ideas are ridiculous only to be proven wrong
eventually.

This is basically how parallax is measured.
Not at all. The traditional way to measure aberration is to
take pictures of an area of the sky at different times of
the year, and compare the relative distances between the stars.

That's exacty what I have proposed....but using an orbit in the ecliptic plane.
If the telescope also orbits the Earth a small diurnal aberration will be
observed. As I stated before, even this can be made to disappear if the
telescope is rotated 1+1/365.25 times per its Earth orbit

The limitation of this method is of course the resolution
of the telescope, and this problem is what must be addressed
if you are trying to find a better way to do it.

My way differs from the conventional way principally in that it gets rid of the
earth's axis tilt. Resolution problems are identical.

And since the tilt of the Earth axis is no problem, any of
the big telescopes can measure the parallaxes equally well.
But since the parallaxes are measured with much better precision
by the Hipparcos, what is you point?

The original point was to show why aberration did not refute BaTh. The later
point was to find an easy way to eliminate abberation....which I have done.

If the same vertically pointing telescope DOES NOT SPIN as it orbits, then the
whole fields DOES NOT rotate around the window either. Rather it 'wobbles' as a
whole due to aberration with each star moving in an additional small circle
(subtending 1AU/Dx) due entirely to parallax. CMIIW
You mean if the telescope doesn't rotate and it's axis always is
pointing in the same direction (like a gyroscope would do).
Yes.

Since the parallax always is 90 degrees out of phase with the aberration
(as you so correctly pointed out), all the stars are moving in circles
with radius _very_ slightly greater than 20.5".

Look at this figure :
p
<--|
|
|a
|
|
|
C

Spin it around C.
The star will appear to be at the arrowhead.
p = parallax << 1", a = aberration = 20.5"
If p is as big as 1" (bigger than any star), the radius = 20.52"

The difference in radius will be minute for any realistic value of p.
It isn't the difference in radius that matters. It is the movement of the
circle centre that indicates the relative distance of the various stars.
Think again, Henri.
There is no movement of the centres of the circles in this case.

You have to spin the telescope around once per year.

The situation is obviously much more complicated when the telescope is pointed
away from the ecliptic pole.
But what is your point with all this?
You cannot seriously propose that parallax could be measured this way?
How do you propose to measure it?
I would leave it to those who are competent to do it.

I know Hipparcos uses a very ingenious method
but I think it still boils down to assessing differences in relative star
positions over six months.
It boils down to measure the change in relative star positions
throughout the year _with an extremely high precision_!
The ingenious method used by Hipparcos could measure the distance
between bright stars to a precision of 1 mas . That's a precision
way beyond the resolution of the telescope.

The designers of Hipparcos addressed the real problem, they didn't
invent an incredible awkward way to measure what was measured before
with much less precision.

the main thing is to rotate the telescope around the right axis once per year
to minimize aberration..

And why do you think aberration is a problem?

Because YOU told me it was.



Henri Wilson. ASTC,BSc,DSc(T)

www.users.bigpond.com/hewn/index.htm.

......
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