During our solar system week - we made a moon out of flour and white paint (however, we ran out of white paint and I used peach). We used bottle caps to make the craters.. I found this craft at: http://www.iheartcraftythings.com/2011/07/story-time-happy-birthday-moon-creating.html
Earth Day craft instructions for "Earth Day Craft with Writing Prompt from IHeartCraftyThings.com. I love the splatter paint to make the stars. Uses a coffee filter for the earth, but if you don't have one on hand, you could make an earth in a number of other ways: torn construction paper or just color your own.