That's a good idea. The bad thing about universe sandbox is that you can't interact much with celestial bodies - you just watch them orbit. I know you can land on it but it is not good enough.
I wish I could walk on it with the arrow keys, look up, look down, jump, etc. Something similar is ok too, as long as I get to interact with the planets. It gets kinda boring when a thing called the UNIVERSE sandbox is, in fact, just a gravity simulator