I was denied access to answer this post, so I'm hoping someone with access will pass this on.
What if you made a sheet cake frosted in dark chocolate frosting, then frost a cupcake yellow to be the sun? Place a tiny sprinkle for the small planets like Mercury, then larger things like silver dragees for the slightly larger planets, and a large gumball for Jupiter. Can mini marshmallows be rolled into planets? Maybe you could sprinkle cinnamon-sugar and mini chocolate chips for the asteroid belt. Wilton used to make nested oval cookie cutters you could use to imprint the orbit patterns.
Hope you find something useful here. Good luck!