Re: We do not know the distance of stars


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

.

Relevant Pages

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  • Re: We do not know the distance of stars
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    (talk.origins)
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