In a large, deep bowl, mix the Jell-O and the unflavored gelatin. Pour the boiling water over the mixture and stir until completely dissolved. Refrigerate for 1 1/2 hr., or until partially set. Meanwhile, use cookie cutters to carve the melons into stars and moons. Press all the fruit into the partially set gelatin, then refrigerate for 4 more hr., or until set.Place the bowl in a pan of hot water to loosen the Jell-O from the sides, then invert onto a wizard-like platter.