Well, my bf's son has a school project to make a solar system, it can be cake, cookies or some other media and she wants something edible. Don't worry, I won't be doing this for him, only providing tools and guidance. Has anyone done anything like this?

I've got two lines of thought here, either a ball cake to be the earth with fondant cutout planets on wires or doing it all in cookies on a board. Any ideas or thoughts about this?

Yep go with that a ball cake, I'ld Make the planets in 3D coming out of it on wires made from fant/ gumpaste. Check out this page and see if it gives you any ides
http://photoshopcontest.com/view-entry/83196/votes.html

Good luck

See my photos for a similar project my son and I worked on. It was alot of fun, and re educating for me!

Don't know if this would help but I did a Petit Prince cake with him standing on his world. You could attach planets on cookie sticks