Re: McCoy does not know the distance of stars

mccoy@xxxxxxxxxx wrote:
"The foregoing illustrates that the surveyor should either avoid using
weak angles in distance computations, or if weak angles must be used,
they should be measure more precisely than would normally be required.

We've been through this before. The above statement is the key. If
you are using "weak angles", you need to be very precise and very
accurate.

Fortunately, we have the ability to measure weak angles very precisely
and very accurately. Therefore the above criteria is met and nearby
star distances can be determined to an acceptable degree of accuracy.

For example, the stated accuracy of the Hipparcos satellite is on the
order of 1 milli-arc-second (1/1000th of an arc second). The base
distance is 93 million miles (Earth's orbital radius) times 2 (300
billion meters). If we use that satellite to measure the distance to a
star that's 1000 light-years away (about 9.5 quintillion meters), we
get an angle of about 3.25 milli-arc-seconds on each side. That gives
us a reasonable ability to determine that said star is in the vicinity
of 1000 light years away (determining error bars is a little
complicated for this case but it might be on the order of a hundred
light years or so).

Measuring distances to stars beyond the order of 10,000 light years or
so requires different techniques. Last time you made this ridiculous
claim, someone posted this web-site providing 26 such approaches.

http://www.astro.ucla.edu/~wright/distance.htm

Now don't make any more claims that we can't determine star distances
until you understand each and every technique proposed there and can
explain, in a mathematically rigorous way, why each of them is totally
inaccurate.

Lee Jay

.

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