Go outside on a clear day and look at the sun. See how generously it pours light upon the whole earth. The sun is so bright that from a full 93 million miles away, it lights up an otherwise dark world. But the sun doesn't only give us light. It makes things grow and flourish; it provides just the right amount of heat to sustain life in all of its variety and beauty. Imagine what the world would be like without the sun: nothing more than a giant ball of ice suspended in a darkened sky.