Star Trek

In just the last eight years, astronomers have discovered a bewildering variety of worlds around other stars: planets so hot they vaporize like comets, planets so large they nearly shine like stars, twin planets that orbit their star in lockstep rhythm. What we have not found is a planet remotely like our own—our instruments aren't sensitive enough. That should change soon. About 10 years from now, NASA plans to launch a mission called Terrestrial Planet Finder, a space telescope specifically designed to detect another Earth. The odds are good that a survey of 150 or so nearby stars will reveal at least one small, Earth-like planet. A sister Earth would not look like much at first, just a faint speck of light nearly lost in the glare of its nearby star. Still, a speck of light is all we need to analyze the mass, temperature, and composition of the new ...