In the mid-1990s, astronomers made history when they detected three planets orbiting stars in the Milky Way. More than 500 planets have been found since then, none of which could support life as we know it. Now, armed with more powerful technology, planet hunters are racing to find a true twin of Earth. Science writer Michael Lemonick’s book Mirror Earth unveils the passionate quest of “exoplaneteers” such as Geoff Marcy, at UC Berkeley, who is the world’s most successful planet hunter having found two of the first three extra-solar planets. There’s also Bill Borucki, at the NASA Ames Research Center, who struggled for more than a decade to launch the Kepler mission, the only planet finder, human or machine, to beat Marcy’s record. And, David Charbonneau, at Harvard, who realized that Earth-like planets would be much easier to find if he looked at tiny stars called M-dwarfs rather than stars like the Sun. Unlike other races of discovery, the scientists consult and cooperate with one another. But only one will be the first to find Earth’s twin.