Re: We do not know the distance of stars

coaster wrote:
Marc wrote:

coaster wrote:

mccoy@xxxxxxxxxx wrote:

......... SNiP


JM,

All you have done here is to fabricate a rule to support a fallacious
argument. There is no such rule that states "less than 1 degree" is
invalid or inaccurate when mapping stars. Astronomers are not trying
to measure the star to within a few millimeters... a few million
kilometers will do.

Modern digital instruments connected to today's optical telescopes can
measure stellar parallax down to 0.02 arc seconds with an error of +/-
.001 arc seconds. An arc second is 1/3600th of a degree. If you do
the math that's good enough to measure stellar distances up to 25
parsecs or about 75 light years away. To date more than one hundred
thousand stars have been mapped in this way.

The whopper of all parallax measurements came last year when a team of
astronomers working with a radio telescope measured the distance from
the Earth to the edge of the outer spiral arm of the galaxy. Measuring
the distance to stars beyond about 75 light years within our own galaxy
is very difficult because they are too far away for optical parallax to
be effective and redshift only works with very distant objects such as
other galaxies. But these guys found a novel way to take advantage of
the special effects of radiotelescopy to perform parallax measurements
on groups of stars more than ten thousand light years away. The very
edge of our galaxy!

http://www.space.com/scienceastronomy/051208_spiral_arm.html


Somehow I get the feeling you are not going to hear back
from him about this within this thread.

Funny, isn't it? (I gave you five stars anyway.)

(signed) marc


Apparently he has stopped posting entirely to this thread. That's
fairly typical, I guess. McCoy failed to respond to similar replies
below. It's difficult for him to argue when sophistry isn't an option.

From McDoofus? What makes you think that sophistry isn't an option?
Outright lying, or plugging his ears and screaming "CAN'T HEAR YOU!" are
by no means beyond his repertoire.

-- Kizhe




.

Relevant Pages

  • Daily # 3986
    ... principal axes and one intermediate axis of each galaxy. ... occur- the first comparative study of globular clusters and their ... recently failed to detect the signature of RGB stars. ... direct determination of the distance to 1 Mpc accuracy using Cepheids. ...
    (sci.astro.hubble)
  • Re: How did we realise we were part of the Milky Way Galaxy?
    ... realised that the Earth was part of the Milky Way Galaxy. ... similar stellar clouds were hypothesized to be, again, composed of stars ... allowed measurements of distances to stars on the galactic scale and beyond. ... One set of measurements plotted the direction and distance of the globular ...
    (sci.astro)
  • Re: We do not know the distance of stars
    ... Marc wrote: ... thousand stars have been mapped in this way. ... the distance to stars beyond about 75 light years within our own galaxy ... the special effects of radiotelescopy to perform parallax measurements ...
    (talk.origins)
  • Re: We do not know the distance of stars
    ... thousand stars have been mapped in this way. ... the Earth to the edge of the outer spiral arm of the galaxy. ... the distance to stars beyond about 75 light years within our own galaxy ... the special effects of radiotelescopy to perform parallax measurements ...
    (talk.origins)
  • Re: Talking about distance
    ... Galaxy left it 2.5 million years ago" followed by "so it might no longer ... there really isn't for closer galaxies either but it just seems a much ... Now if you look at objects within our own galaxy such as stars, nebulae, ... depending on distance from us. ...
    (sci.astro.amateur)