numbernu...@gmail.com writes:
>"Parallax is not "Parallaxwhat you think it is, and only works for fairly
close
>stars"--pnal.
>______________________________________________________
>Your statement is patently incorrect since the stellar universe is
>stationary.
Why would you claim that? All stars including the sun are moving relative
to each other as they have their own paths through the galaxy and orbit
its center.
Many stars are so far from us that they appear "fixed". Others are closer
and we can detect them moving relative to the distant stars. Look up
proper motion. We can also detect redshift or blueshift in their
spectral lines. There is one star (forget its name) that is dozens of
light years away but heading almost straight toward us, in many thousands
of years it will pass as close as a light year away from us.
>In addition, the proper motion is cause by the earth's yearly and daily
> motions
Congratulations. You just discovered Parallax. If we plot the position
of a close star against the distant stars over the period of a year,
it will appear to move in a tiny ellipse. This is caused by the earth's
orbital motion, not any motion of the star (however its proper motion
has to be dealt with separately). The size of the ellipse tells
us how close the star is, the further away it is the smaller the ellipse
until you consider the distant stars whose ellipse is too small to
measure.