I made one, and my friend is helping and stuff. Umm... I know there is another topic on this, but I can't seem to find it.
You can make a whole set of pages of your solar system, planets, moons, comets...
Make an alien race to go with it
Yes, you can <b>just</b> go on Galaxiki, but on there, it is preset planets and moons... here, you can put how many you want, the orbits and stuff! Yes, you can also use universe sandbox, but then you don't have the information about them! Describe them!
You can use Spore animated GIFs for the planets, and take pictures in Spore of the System, even base your system off of a system you found in Spore!
Oh, btw, you can put Spore videos.
Did I persuade you to go there? Hope so.
Edit: did I forget the link AGAIN?
http://yoursolarsystem.wikia.com/