The Waterfall Nebula

Pretty, isn't it? Click for larger version. I found it on the Astronomy Pic of the Day site, which is run by NASA. Alas, it's not big enough to use as a desktop photo.

No one knows why the nebula assumed this shape. No known theory explains it. But that just makes it more beautiful, no?

Photo credit: Z. Levay (STScI/AURA/NASA), T.A. Rector (U. Alaska Anchorage) & H. Schweiker (NOAO/AURA/NSF), KPNO, NOAO