Planets are static, they can't be made to move. Actually, I don't recall any 4X or space strategy game... or any game whatsoever which simulated a fully animated solar system. The last game I remember doing that was Elite: Frontier... though come to think of it I am not sure if even that masterpiece of realism had orbiting planets. I know it was hard enough landing on them as it was.

It's been brought up multiple times; but every single time it got shot down.  The ever-changing nature of the system landscape made it impracticle to implement orbiting.

Thats the thing though, it would take a heck of a lot more computing power than what is in a typical PC to handle the movements of a solarsystem like ours, let alone a multiple solarsystems like Ancient gifts. Maybe once we start describing memory in tetrabytes it might be possible but...

Shattered Suns, which just came out recently has orbiting planets. I played the Beta briefly, and did not like it, and it got horrible reviews. However, I did like the idea of not only orbiting planets, but also orbiting moons.