Earth and Sun
What a beautiful, well designed and informative explanation of the complex earth / sun relationship.  Well done!<p>One thing I would love to see is the path of the sun across the sky for different times of year, and different locations on earth.<p>Here in Seattle, the difference is fairly dramatic between winter and summer, and I've come to realize that the sun is never directly overhead, not even in summer.  It would be interesting to see the difference between polar regions vs in the tropics also.