Realisticly, what you should probably do is keep your ship at 0,0, and keep track of planetary motion yourself, and then simply render stuff relative to your ship (culling out objects that are too far away to see)
Also, you might want to check out the forums at the Orbiter web site (http://www.medphys.ucl.ac.uk/~martins/orbit/orbit.html) ... Orbiter is a freeware space simulator (realistic space simulator, as in Soyez craft, Apollo craft, Space Shuttles, Voyager probes, etc.), and they seemed to work out the whole planetary system rendering. Also, it has a SDK for developing space-craft plugins (there is a whole MOD community who develop space craft), and it might give you some insight into how they handle their rendering.
Also, you might want to check out the forums at the Orbiter web site (http://www.medphys.ucl.ac.uk/~martins/orbit/orbit.html) ... Orbiter is a freeware space simulator (realistic space simulator, as in Soyez craft, Apollo craft, Space Shuttles, Voyager probes, etc.), and they seemed to work out the whole planetary system rendering. Also, it has a SDK for developing space-craft plugins (there is a whole MOD community who develop space craft), and it might give you some insight into how they handle their rendering.