I was curious so i fiddled in the sky lab - you can move the rainbow with the sun control and change the colors that way also. and you can make the rainbow bigger or smaller with the skylab rainbow control and just animate in the skylab direct adding a keyfranme for the sun motion, halo and sun colors. (or just choose all in the sun keyframe option)Let me know if you need setting as reference

this animation is very cheesy but it was just to show movement

roch222