It took humans thousands of years to explore our own planet and centuries to comprehend our neighboring planets, but nowadays new worlds are being discovered every week. To date, astronomers have identified more than 370 “exoplanets,” worlds orbiting stars other than the sun. Many are so strange as to confirm the biologist J. B. S. Haldane’s famous remark that “the universe is not only queerer than we suppose, but queerer than we can suppose.” There’s an Icarus-like “hot Saturn” 260 light-years from Earth, whirling around its parent star so rapidly that a year there lasts less than three days. Circling another star 150 light-years out is a scorched “hot Jupiter,” whose upper atmosphere is being blasted off to form a gigantic, comet-like tail. Three benighted planets have been found orbiting a pulsar—the remains of a once mighty star shrunk into a spinning atomic nucleus the size of a city—while untold numbers of worlds have evidently fallen into their suns or been flung out of their systems to become “floaters” that wander in eternal darkness.