a matter of truth

[ValiantSL]

English is not my native tongue. I apologize for flaws.

Suppose we look at a galaxy, far away, sideways, as a partly flat disk.
Suppose that gallaxy spans about a 100.000 lightyears.

The light of the furthest stars will travel about 100.000 years before it joins the light of the nearest (to us) stars in the galaxy. After that they travel both across space to our eyes.
That means that we do not see( in photographs) reality. The galaxy has turned at the far site for a hundred thousand years before the furthest light of the galaxy meets our eye (and the photograph). So we see the nearest edge 100.000 years before the farthest edge.

We see the (beautiful) photographs.
Is the above mentioned true,than we know that they do not represent reality.

The question is: Is it possible, that the galaxy turned in such a way that the filaments,usually seen in photographs, are influanced by that timespan of 100.000 years.
I am aware: it's complicated.

I hope this is sufficiently clear.
Can I get an answer via email?:

Simon Lamens,
Park vossendijk 36,
3192 XL Hoogvliet,
The Netherlands.
Tel: 010=4381861.
email: s.lamens@upcmail.nl

[Chris Peterson]

The question is: Is it possible, that the galaxy turned in such a way that the filaments,usually seen in photographs, are influanced by that timespan of 100.000 years.

What you are describing is related to the phenomenon known as aberration of light. In the case of galaxies, the typical distance variation along our line of sight is measured in tens of thousands of light years, and the typical rotation times of galaxy components is tens to hundreds of millions of years. So the actual distortion introduce by the aberration of light is quite small, and doesn't really show up as any sort of structure we can see.

[rstevenson]

It is with considerable trepidation that I dare to correct you Chris, but since my correction is based on what I think the OP was asking rather than any issue of astronomy, I will step forth.

I think the OP was asking about Light-time correction. The only reason I know anything about it is that I read the Aberration article at Wikipedia that you linked to, and the one I'm linking to is mentioned there.

If I'm reading that article correctly, it would seem the Light-time_correction effect on our view of a galaxy would be essentially nil. Certainly not enough to cause the appearance of spirals, as I think the OP was wondering.

Rob

[Chris Peterson]

I think the OP was asking about Light-time correction. The only reason I know anything about it is that I read the Aberration article at Wikipedia that you linked to, and the one I'm linking to is mentioned there.

That might be a better term, although I'd be inclined to qualify it the same way I did aberration of light, which is to say that the phenomenon described by the OP is related to light-time correction. What we're seeing depends on a comparison of the effects of transverse motion of two sources at different distances.

If I'm reading that article correctly, it would seem the Light-time_correction effect on our view of a galaxy would be essentially nil. Certainly not enough to cause the appearance of spirals, as I think the OP was wondering.

I don't know about "essentially nil", but certainly the effect is a small one. I'm not sure what structure the OP was referring to, but neither the spirals nor any other observable structure is created by any kind of light travel time effects. This is fairly obvious when you consider the fact that we see the same sorts of structure in nearly edge-on galaxies that we see in face-on examples. The latter obviously are not subject to any light travel time effects.

[neufer]

I think the OP was asking about Light-time correction. The only reason I know anything about it is that I read the Aberration article at Wikipedia that you linked to, and the one I'm linking to is mentioned there.

That might be a better term, although I'd be inclined to qualify it the same way I did aberration of light, which is to say that the phenomenon described by the OP is related to light-time correction. What we're seeing depends on a comparison of the effects of transverse motion of two sources at different distances.

Exactly, and the aberration of light has nothing whatsoever to do with either the motion or the distance of the source.

To say that the two "are related" is misleading, IMO.

<<The aberration of light (also referred to as astronomical aberration or stellar aberration) is an astronomical phenomenon which produces an apparent motion of celestial objects about their real locations. It was discovered and later explained by the third Astronomer Royal, James Bradley, in 1725, who attributed it to the finite speed of light and the motion of Earth in its orbit around the Sun. At the instant of any observation of an object, the 0apparent position of the object is displaced from its true position by an amount which depends solely upon the transverse component of the velocity of the observer, with respect to the vector of the incoming beam of light (i.e., the line actually taken by the light on its path to the observer). The result is a tilting of the direction of the incoming light which is independent of the distance between object and observer. Aberration should be distinguished from light-time correction, which is due to the motion of the observed object, like a planet, through space during the time taken by its light to reach an observer on Earth. Light-time correction depends upon the velocity and distance of the emitting object during the time it takes for its light to travel to Earth. Light-time correction does not depend on the motion of the Earth—it only depends on Earth's position at the instant when the light is observed. Aberration is usually larger than a planet's light-time correction except when the planet is near quadrature (90° from the Sun), where aberration drops to zero because then the Earth is directly approaching or receding from the planet. At opposition to or conjunction with the Sun, aberration is 20.5" while light-time correction varies from 4" for Mercury to 0.37" for Neptune (the Sun's light-time correction is less than 0.03").>>

[neufer]

The question is: Is it possible, that the galaxy turned in such a way that the filaments,usually seen in photographs, are influanced by that timespan of 100.000 years.

The light-time correction distortions (while quite small) are morphological similar to Dali Clock distortions
where the more distant hour hand is delayed to the left while the nearer minute hand is advanced to the left:



The vector of the bending distortion is proportional to R x L where:
R is the galaxy position vector (vis-a-vis the observer) and
L is the angular velocity vector of the spiral arm or bar feature.