For orbiting planets :
- First, get yourself a function, that puts the planet on the right spot based on a fraction (0-1, 0-360 or 0-2PI). For circles, you simply use cos, sin, and multiply by the distance. If you want proper orbits, they are elipses, with the sun as one of the focus points.
- Then, use a Tween to call your function repeatedly, over the desired time and interval.
For your trajectory, either calculate it yourself, or just shoot little indicators, with the same physics as your spaceship.
For navigation, I have no clue what you mean by that. If it is camera movement related, then you will also want to use Tweens to make the movement more natural.