Planets circle the stars that dot the heavens. Before 1995, we couldn’t have said that with any certainty. Now we know of more than 300 planets orbiting distant stars, and we have a fleet of telescopes looking for them. The ultimate goal is to find another Earth orbiting a star like the Sun, but the quest on the way to that Holy Grail has yielded some strange benchmarks. CoRoT-exo3b, a dense planet orbiting another star COROT-exo-3b compared to Jupiter Meet the planet COROT-exo-3b. It orbits a star slightly larger, hotter, and brighter than the Sun. The star is not an...