Go into the cannon left of the Chomp Chomp near the more open area and toward the sun, then point it at the cloud below the sun. Aim so that the bottom arrow of the target is almost touching the middle bottom part of the cloud. Fire to fly into a fence and the top part of the screen will turn blue. You will then fall straight out of the sky. You can even go out of the level if you move while still high in the sky.