I watched a wonderful animation on youtube recently: http://www.djsadhu.com/the-helical-model-vortex-solar-system-animation/ Which, except for the fact that Sol also bounces up and down in a sinusoidal path with respect to the plane of the Milky Way, I considered to be quite accurate. I never doubted any of this. It's just the way celestial mechanics works as observed by someone following a parallel trajectory with respect to Sol from some point outside of our solar system. There is another video of the motion of our galaxy by the same computer artist which I have not yet watched. And then I read this: http://www.slate.com/blogs/bad_astr...ing_sun_s_motion_through_galaxy_is_wrong.html which completely confuses the issue of what is "reality". "Reality", as far as any of us is concerned, always requires two observers, at a minimum, to make sense of events at any level. Or to put it another way, without at least two observers, no single event can be decided in terms of whether it ever happened. Have I missed something here? What really is the point of refuting a given view of anything? There are even die-hard Ptolemists who believe we should keep teaching about "epicycles" of the planets further from the Sun than Earth in astronomy. It's like we never really left those dark ages, and I couldn't have framed the idea better than these two articles have already done. Which one do you think is closer to reality?