Astronomers and astrophysicists have learned that the climates and weather patterns of planets in the solar system are driven by many of the same physical processes that create the Earth's environment; that stars form out of clouds of gas and eventually die either in quiet solitude or spectacular explosions; that most of the common chemical elements are created in explosions of stars; that stars group together in isolated galaxies; that galaxies and clusters of galaxies stretch in sheets and filaments as far as the largest telescopes can see; and that the universe itself was born in a violent explosion some15×109years ago. Most amazingly, we have learned that the laws of nature on Earth apply to the farthest reaches of the observable universe.