by Nitpicker » Thu Nov 27, 2014 4:41 am
I'm assuming the analogy was pertaining to how dark nebulae form into filaments, and not just what the filaments look like (because we have photos of the filaments).
So, assuming the dark nebulae are originally sheet or shell-like, we see them most vividly when the sheets are edge-on to us (for the same reason that the spherical shell that is the Bubble Nebula, looks brighter around the perimeter of its apparent circle, than in its middle). Gravity ends up deforming the sheets in interesting ways, but we still only see the dark nebula where its essentially 2-D sheet structure is thick enough in our line of sight. This is where the cinnamon formation analogy falls down, in my opinion, because we shouldn't be able to see the cinnamon from the top, but only from edge-on, and the surface of the oatmeal remains undeformed until you start eating it. (I didn't mean for this analysis to go quite as far as it has, but that is how I've been looking at it.)
I'm assuming the analogy was pertaining to how dark nebulae form into filaments, and not just what the filaments look like (because we have photos of the filaments).
So, assuming the dark nebulae are originally sheet or shell-like, we see them most vividly when the sheets are edge-on to us (for the same reason that the spherical shell that is the Bubble Nebula, looks brighter around the perimeter of its apparent circle, than in its middle). Gravity ends up deforming the sheets in interesting ways, but we still only see the dark nebula where its essentially 2-D sheet structure is thick enough in our line of sight. This is where the cinnamon formation analogy falls down, in my opinion, because we shouldn't be able to see the cinnamon from the top, but only from edge-on, and the surface of the oatmeal remains undeformed until you start eating it. (I didn't mean for this analysis to go quite as far as it has, but that is how I've been looking at it.)