Scientific American - The Frontiers of Space [antikvár]

FROM THE EDITORS Dear Scientific American Subscriber: Once upon a time, say, 2,000 and more years ago. Earth was the only world in the universe and the planets were just wandering lights in the sky. So the Greeks believed, anyway. Our understanding of the universe has expanded just a bit since then. This solar system is home to seven or eight other planets (depending on whether you accept Pluto as a full member of the club), scores of moons and countless icy or rocky smaller bodies that occasionally glitter in our night skies but usually lurk in the farthest, darkest provinces. Moreover, astronomers have identified what appear to be dozens of planets circling other stars—planets that are often gargantuan and following bizarre orbits. Today we can only guess how many planets our galaxy might hold, and whether any of them other than ours has life, and whether that life thinks its world is the only one. Everywhere we have turned in space, new discoveries have shown us how much more we still need to learn. This anthology of articles from Scientific American reviews some of the fascinating highlights of those explorations—past, present and future. It carefully considers what it will take for us to visit our planetary neighbor. Mars, and takes you beyond on a guided tour of the asteroid belt and the satellites circling Jupiter. It discusses where we might best look for alien life, whether on Mars, or within the frozen seas of the moon Europa, or on planets we haven't yet even discovered. And in case this universe somehow feels a little cramped, it also considers how we might be able to probe parallel universes. At Scientific American, it is our pleasure to chronicle mankind's endlessly fascinating advance into space and to convey the tales of wonders to be found there. I hope you enjoy reading these stories as much as we enjoyed collecting them, and that you will join us for the rest of the adventure in the years ahead. Sincerely, ^ /L^ John Rennie Editor in Chief