Far from being a lifeless ornament in the sky, the Moon holds the answers to some of science's central questions. Silent, dry, and barren, Earth's 4.34-billion-year-old companion is essential to life on earth. Its gravity stabilized the Earth's orbit, and, as it once guided evolution, its tide stirring up nutrients that fostered complex life, it now influences everything from animal migrations and reproduction to the movements of plants' leaves. More...