Galaxy changes...

[kfsone]

I realize the answer is probably "No", but I wondered if anyone had put together sequences of visual images of any one particular galaxy over time? (Specifically images designed for comparison rather than mosaics of random snaps of the same target).

No, I'm not expecting to see starry pinwheels spinning madly like the CG animations of galaxy collisions etc, or even the entrancing whorlpools of scifi shows.

Rather quite the opposite (100 years of Andromeda: spot the pixel that changes due to a fly passing over the lens on Dec 15th 1999). But I was also rather curious, specifically, if we had any duration of such pictures taken from opposite sides of our solar orbit. I realize that's like taking pictures of a tin can a mile away from opposite sides of a human hair... And while we're more likely to see canals on mars than spicules on the surface of the sun... I was just curious whether such images would elicit anything in the human visual system - illusory or otherwise

- Oliver

[Chris Peterson]

I realize the answer is probably "No", but I wondered if anyone had put together sequences of visual images of any one particular galaxy over time? (Specifically images designed for comparison rather than mosaics of random snaps of the same target).

No, I'm not expecting to see starry pinwheels spinning madly like the CG animations of galaxy collisions etc, or even the entrancing whorlpools of scifi shows.

Rather quite the opposite (100 years of Andromeda: spot the pixel that changes due to a fly passing over the lens on Dec 15th 1999). But I was also rather curious, specifically, if we had any duration of such pictures taken from opposite sides of our solar orbit. I realize that's like taking pictures of a tin can a mile away from opposite sides of a human hair... And while we're more likely to see canals on mars than spicules on the surface of the sun... I was just curious whether such images would elicit anything in the human visual system - illusory or otherwise :)

We are too far from even the nearest galaxies to see any parallactic motion from our orbit around the Sun. And we haven't been observing long enough to see any proper motion of stars in other galaxies. If we're here in a few thousand years, we might be able to observe some structural changes in galaxies other than our own, however.

[kfsone]

Chris, in the original post I said: "Rather quite the opposite" Something that actually emphasized the scale by the very lack of change.

Imagine a HD Video with four panels... Starting with 2 panels. Left: 100 years of Andromeda. Right: 100 years of some earthbound town. After a while, it splits into four panels. Top left still andromeda, top right still the same town/street. Bottom left now X years of another astronomical target (a local nebulae perhaps) and on the right satellite pictures of earth...

In every image, change, except the "neighboring" galaxy...

On the other hand - the curiosity part at the end -- if nobody has compared any kind of extended period of such pictures, how can we be certain that no identifiable dynamic is going on? No, I don't actually imagine or expect there would be - but assumption isn't very scientific, is it

[Chris Peterson]

On the other hand - the curiosity part at the end -- if nobody has compared any kind of extended period of such pictures, how can we be certain that no identifiable dynamic is going on? No, I don't actually imagine or expect there would be - but assumption isn't very scientific, is it :)

Ah. Well, actually these kinds of comparisons are made. I was careful in my earlier comment to refer to stellar changes: we don't see stars changing positions, or arms rotating. But there are other elements that can show change- nebular regions or jets, for instance.