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Re: Directional Flow

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Posted by Paul Rest/">Paul Rest on January 2, 1999 00:23:37 UTC

I didn't see that photograph, but I can tell you a thing or two about spiral galaxies. There is no law in the universe that says sprial galaxies must spin a certain way, therefore they go any way they want, which is probably dependent on the way in which they form. However, I can see you are suffering under the common misconception about spiral galaxies that they act like whirlpools, they do not. All a spiral galaxy is is a disk a material, stars, gas, dust, whatever. The spiral shape comes from the fact that there are "density waves" traveling through the galaxy's disk spurring star formation. Since the stuff that is orbiting a galaxy's center near the center is traveling at the same speed as the stuff near the edge of the galaxy, it completes its orbit faster. The end result of of this is these "density waves" of star formation get stretched and pulled out into those beautiful spiral arms we see. Hope this helps.


: In the latest pictures from HST of NGC 7742 it appears that this 'system' is spinning in a counter-clock wise direction. Is this most probably due to the position of NGC 7742 in relation to HST, or can it be attributed to gravitational pull? The same pull that makes water going down a drain flow counter-clock wise in the northern hemisphere and clock wise in the southern hemisphere. (Assuming that is what makes that occur on earth)

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