Nice job, Sparky. Hint: use -visscale 4 so you can place the Earth farther away and it won't disappear due to distance.
Also, I *think* you can alter the draw distance by using the Level Of Detail command:
Lod
Scale 50
End
Put that inside the group (that is, after the "Group" items, but before the "End" of the Def) and play with the scale number, let me know if you notice a difference.