Imagine that you're a Chinese lantern, a bright, shining light which drifts gracefully above the ground, floating steadily higher and higher. You float up high above the ground into the night sky. It's beautifully clear night, with stars shining brightly around you. As you float gently through the air, you begin to notice light below you. Look closely at these lights and realize that they are the lights of houses, cars and streetlights way below you