Star distances (triangulation method etc.)

[Siggy_G]

I'm wondering if anyone can elaborate on the current methods for measuring distances for stars and galaxes. I understand it's partially the triangulation or parallax method, where the change in star position is detected in comparative images, usually with halfyearly recordings.

But it is also said that this only works for nearby stars (some lightyears away). I'm kind of surprised it even works there, because the angle is extremely tiny - i.e. the smalles cathesus being 16 light minuttes and the other sides a few light years. Not that tiny or gigantic numbers are any mathematical problem, but it demands extreme accuracy from the instruments - plus relative motions could be argued.

Then what about the distant stars? Only redshift method?

Which leads me to another major question. When they claim that red shift is proportional with the star distance, how accurately and true is that? It can't be validated for the distant stars, if only red shift is used as distance detection method.

Determining star luminocity or size seems unclear to me as well, because we have different star types/sizes, different radiation strength, different distances etc.

[earls]

http://www.straightdope.com/columns/rea ... ial-bodies

Basically, if you screw up any of those steps, then all your distances are going to be whack... Which they are.

http://en.wikipedia.org/wiki/Redshift

EU is very big on "intrinsic" redshift. Some discount redshift of the moving celestial bodies completely. I personally believe that is as big of a mistake as mainstream not accepting sources of intrinsic redshift.

The Electric Sky details the objections... Certainly you've read the book?

More can be found on http://thunderbolts.info/tpod/00subjectx.htm#Redshift and http://www.holoscience.com/news.php

[Siggy_G]

Alright, thanks for the reply and links. They explained some of it, although I'm still not convinced about the apparent brightness versus "actual" brightness i.e. to which extend this can be determined for sure (what type of star is observed).

As for red shift, yes, I agree with the objections and have read the "Universe Electric" e-book plus seen the "Cosmological Quest" documentaries. I was just wondering what the current methods are, and how mainstream cosmologists justify using red shift as a distance indicator. Even triangulation / parallax method seems questionable, but I haven't seen source images that indicates its accuracy.

[earls]

I dunno.

Don't get me wrong, I agree with you, it's just that "it is what it is."

To anyone with half a brain, it should be obvious that although certain methods will accurately dictate the distance for certain objects, because of the umpteen variables you can't just take a large generalized survey and then extrapolate the distance of all objects based on a astronomically small set of data.

While I'm sure they quantify distances via other methods, it appears to me on the surface that they have deduced a "redshift equation" which is the very first thing applied to object and usually the distance measurement published along the lines of "object X discovered in 2001 is at location Y with the redshift of Z so object A that we just found has the redshift of B and the distance of C."

Justifying redshift for them is easy: "Einstein!" The speed of light is constant through a vacuum, space is a vacuum, light is waves, waves shift via the Doppler effect which indicates distance!

Triangulation/Parallax I'm less familiar with, but that uses the brightness? The "standard candle"... Even mainstream will tell you it's not so "standard" anymore.

I'm sure they're open to suggestions as they have many "mysteries" to be solved because of many "bizarre" distance measurements.

This is about the extent of my knowledge, this particular facet hasn't really captured my attention as I take the "expansion" of the Universe at face value. Distance to nearby stars doesn't much matter to me if we have yet to mastered gravity and propulsion...

[james weninger]

All three ways to measure distance are greatly flawed.
Halton Arp's book, "Seeing Red" is the best source for showing what is wrong with the redshift method. If,as he shows,we can have a highly redshifted object in front of a low redshift object ,or two objects of highly different redshift visibly connected, then using redshift to measure distance is clearly flawed.
As far as the paralax method: Not only does it require extreme acuracy and only work for nearby stars,but it assumes the solar system is relatively stable in space. If the solar system is spiralling through space due to E-M fields(for example), then measurements will be off for that reason too.
Finally, can we trust the measurement of distance by brightness of a star? Remember, we calculated size/brightness in the first place by assuming we knew how far away stars were in the first place.
Short answer: We have no definite way of knowing how far away any star really is.

[nick c]

[url2=http://hyperphysics.phy-astr.gsu.edu/Hb ... ce.html#c1]Tools used for measuring distances in astronomy[/url2].

[james weninger]

[url2=http://hyperphysics.phy-astr.gsu.edu/Hb ... ce.html#c1]Tools used for measuring distances in astronomy[/url2].

With this list of 8 ways to measure distance,you may be inclined to have more faith in astronomer's measurements of distances in space.
However,notice the first measurement,parallax, is inaccurate at best. The last measurement,redshift,can be totally wrong. And all the others are just variations of the distance/brightness idea. They are good for comparing relative distances of similar objects,but not absolute distances. And how do we calibrate this distance/brightness scale? You guessed it, by measuring the distance to one of the objects with redshift or paralax measurements.

[james weninger]

I don't mean to beat this point into the ground,but look at the parallax distance to the Pleiades measured from Earth (440 light years),compared to the Hipparcos measurement (387 ly). Quite a difference. So much for trusting parallax.

When astronomers get redshift distances that are clearly wrong,are they not free to explain away that redshift difference by giving the object an arbitrary radial velocity.

When luminosity/distance measurements are not working,can't astronomers postulate an amount of interstellar dust to cause the required reduction in luninosity?

I know I am ranting,but this is why it is important to me: Our solar system is curving about the Pleiades. The parallax distance measurements to the Pleiades are therefore to high.
(if our solar system is curving through space due to E-M,parallax distances towards our center of curvature will be measured high) The Hipparcos platform was fixed to distant stars,not our sun. Therefore the distance measurements by Hipparcos will be more accurate. This is not what astronomers are saying. It's the Hipparcos measurements they question.

[Heftruck]

http://img18.imageshack.us/img18/263/sunsizediagram.png

An image can say more than a thousand words.

Sol as seen from Neptune appears as nothing more than a very bright star among a great lot of other stars.

Would it be absurd to think that other stars could be a whole lot more closer to us than presently assumed? Could the distance to the nearest neighboring stars be of magnitude of five to ten times the distance from Sol to Neptune (or less) instead of many lightyears?

What is the reason for the claim of distances so gigantic that they have to be measured in lightyears?

[nick c]

Tools used for measuring distances in astronomy.

As I have stated on another thread where this subject came up, I do not necessarily endorse the accuracy of all or any of these methods, but am merely putting it out there as the standard techniques used by astronomers. Most here are familiar with the problems associated with the assumption of the red shift as a measurement tool.
It seems to me that there can be no argument that great distances are involved. Logically, it can be calculated at how far the sun would have to be removed to have it's apparent luminosity reduced to that of a star. No doubt, most stars visible in our night skies have a much brighter [url2=http://www.astronomynotes.com/starprop/s4.htm]absolute magnitude [/url2] than the Sun. Whether a star is 50 light years away or 30 light years away, is certainly relevant, but either figure is an incomprehensible, to the human mind, distance. Furthermore, galactic distances are orders of magnitude of even greater mind boggling distances. These can be estimated by measuring the luminosity of globular clusters that surround most galaxies, and are themselves composed of many thousands of stars. So, while we should take the distances mainstream tells us with a grain of salt, rest assured that these are objects are very very very...far away.

nick c

[Lloyd]

* James W said the 2 different measurements for the Pleiades are 440 ly and 387 ly. That's a difference of 14%. If the latter measurement is more accurate and if most measurements are done by the first method, then multiplying by 88% will give a better answer. Since we're not building galaxy-wide structures yet, it seems that such estimates should be close enough for now.
* It seems like Arp's reckoning was that the known universe is likely about 10% the size that redshift calculations indicate. Since the most distant quasar is said to be 13 billion ly, I think, it's probably close to 1 billion ly.
* I think the average distance between adjacent galaxies is 2 million ly, while the average large diameter is a little over .1 million ly. So about 20 galaxies could fit between each pair. I don't know what the average velocity of the galaxies is, but cars on the road are supposed to stay several carlengths apart for safety. I hope 20 galaxy-lengths is enough for galaxies. If one of them puts on the brakes suddenly, there could be a 50 galaxy pile-up.
* I disagree with Nick [was it?] about those distances being unimaginable. It seems pretty easy to imagine them according to ratios.
* For example: Earth is about 107.5 Sun diameters from the Sun. The Sun is 109.5 Earth diameters in diameter.
* Neptune is 30 A.U. from the Sun, 30 times Earth's distance. The nearest star is about 8,300 Sun-Neptune distances from the Sun.
* Out here in the Milky Way boondocks, our star neighbors are pretty far apart, but in the big city of the galactic nucleus, they're a lot closer together.
* I don't have time to finish.

[rcglinsk]

A lot of EU/PC folks like Arp's tired mass theory of redshift, but I prefer explanations along the line of the following:

http://arxiv.org/PS_cache/astro-ph/pdf/ ... 1420v3.pdf

A new interaction, plasma redshift, is derived, which is important only when photons penetrate
a hot, sparse electron plasma. The derivation of plasma redshift is based entirely on
conventional axioms of physics, without any new assumptions. The calculations are only more
exact than those usually found in the literature. When photons penetrate a cold and dense electron
plasma, they lose energy through ionization and excitation, through Compton scattering on
the individual electrons, and through Raman scattering on the plasma frequency. But when the
plasma is very hot and has low density, such as in the solar corona, the photons lose energy also
in plasma redshift, which is an interaction with the electron plasma. The energy loss of a photon
per electron in the plasma redshift is about equal to the product of the photon’s energy and one
half of the Compton cross-section per electron. This energy loss (plasma redshift of the photons)
consists of very small quanta, which are absorbed by the plasma and cause a significant heating.
In quiescent solar corona, this heating starts in the transition zone to the solar corona and is
a major fraction of the coronal heating. Plasma redshift contributes also to the heating of the
interstellar plasma, the galactic corona, and the intergalactic plasma. Plasma redshift explains
the solar redshifts, the redshifts of the galactic corona, the cosmological redshifts, the cosmic
microwave background, and the X-ray background. The plasma redshift explains the observed
magnitude-redshift relation for supernovae SNe Ia without the big bang, dark matter, or dark
energy. There is no cosmic time dilation. The universe is not expanding. The plasma redshift,
when compared with experiments, shows that the photons’ classical gravitational redshifts are
reversed as the photons move from the Sun to the Earth. This is a quantum mechanical effect.
As seen from the Earth, a repulsion force acts on the photons. This means that there is no
need for Einstein’s Lambda term. The universe is quasi-static, infinite, everlasting and can
renew itself forever. All these findings thus lead to fundamental changes in the theory of general
relativity and in our cosmological perspective.

[moses]

So light can be curved by electrical means. And the parallax measurements
are based on light travelling in straight lines. Thus even the closest stars
may be at a dramaticallty different distance if the light from such a star
curves when travelling to the Solar System.
Mo