Lots of learning was involved before I got this far:
- evaluating and deciding on a flash 3D engine (Away3d)
- efficiently implementing and caching filters for large images
- perspective projections. Note for next time: you do _not_ see half the sphere after projecting it to 2D but significantly less
- The day/night line is calculated and updated in realtime (let the program run for a while to see it). Some funky math and astronomy was required to get this just right
- Quaternions. For smoothly rotating the camera around the globe without running into gimbal lock
- lots of Actionscript idiosyncracies, this is my first flash program after all
I'm quite satisfied with the results. Now I need to add stars to the background and figure out how to best draw flight paths and markers on the surface of the sphere.