Human history becomes more and more a race be-
tween education and catastrophe.
—H. G. Wells, in The Outline of History (1920)
A lot has happened in the relatively short time since this book first went into print, and I’m fortunate to have an opportunity to tell you about some of the most important events. Let’s start with a milestone: In 2009, the world celebrated the 400th anniversary of the discovery that we are not the center of the universe. The United Nations designated the year as the International Year of Astronomy, and hundreds of special events took place around the globe.
The discovery didn’t really happen all in a single year, and if you look back at our discussion of the Copernican revolution in chapter 2, you’ll see that the full story unfolded over a period of more than a century. Still, the year 1609 was pretty special. It was the year in which Johannes Kepler published his first two laws of planetary motion, showing that we could make sense of the long-mysterious motions of the planets by removing Earth from a central location and placing it on an elliptical orbit around the Sun. It was also the year in which Galileo first turned a telescope to the heavens, making observations that demonstrably contradicted the ancient tenets of an Earth-centered universe. For example, he observed patterns of shadow on the Moon that proved he was seeing mountains and valleys, and changing groupings of spots on the Sun; both sights counted as “imperfections” in what had previously been assumed to be the perfect and unchanging heavens. He watched Venus over many months, observing phases that proved it was orbiting the Sun, not Earth. Perhaps most important, he observed Jupiter night after night, discovering that it was always accompanied by four “stars” that clearly orbited it. We now know these “stars” to be Jupiter’s four largest moons, and their existence offered definitive proof that Earth was not the center of everything.
Changing one’s deeply held beliefs is never easy. Clear as the case may seem with hindsight, many of Galileo’s contemporaries put up fierce resistance. Some refused his invitations to look through the telescope for fear of what they would see. The pope summoned Galileo to Rome, where an inquisition ultimately sentenced him to spend the rest of his life under house arrest. Even today, while no one seriously argues for an Earth-centered universe any longer, many people still act as though they hold a central