Designate the largest ball as Jupiter. If possible, color it with streaky markings to simulate the clouds have four much smaller balls for the galilean moons the closest one (Io) should be a bit less than three times the diameter of jupiter (the largest ball) from jupiter this one can be colored to look like a "diseased pizza" (red and white with dspark blotches like pepperoni or much-rooms) next europa should be an off white and about twice as far from jupiter then ganymede which ought to be a bit larger than the first two and a mottled gray and brown with white splashes