Horse Head Neb

[kev 102 42]

how come it dosent change shape if its gas and dust...........kev

[Psychobilly]

I guess it probably does over a longer period of time...I guess we are not around long enought to notice the differences... but other younger objects like M1 show changes that are visible between images a few decades apart...

[Parallax]

The way I usually explain this is :-

Look at the smoke from, say, a bonfire - the "shapes" change quite rapidly.

Now scale it up and look at a cloud - the "shapes" don't appear to be changing but obviously they are. The clouds are huge in comparison to the smoke and also further away.

Now scale it up even more to a nebula - these are ~1500 LY away and millions of miles across.

You get the idea.

Steve

[kev 102 42]

Cheers Chaps............kev