I want to build a model of how the ecliptic interacts with the horizon. The horizon appears to be a flat circle, so I thought I'd use a CD sized shape for that. What shape would I use for the ecliptic, and how large relative to the CD? I would like it to be as close as possible to the my horizon at all times of the day. I'm at 45 degrees lat. I tried with a circular ecliptic just a little larger that the horizon, but when I rotated the part that repented the ecliptic, it seem to hit the horizontal piece (the CD I'm using as the horizon). I thought this might be a geometry question of some type.