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A short history of nearly everythingThen we will have problems. After Christy spotted PlutoБЂ™s moon, astronomers began to regard that section of the cosmos more attentively and as of early December 2002 had found over six hundred additional Trans-Neptunian Objects, or Plutinos as they are alternatively called. One, dubbed Varuna, is nearly as big as PlutoБЂ™s moon. Astronomers now think there may be billions of these objects. The difficulty is that many of them are awfully dark. Typically they have an albedo, or reflectiveness, of just 4 percent, about the same as a lump of charcoal-and of course these lumps of charcoal are about four billion miles away. And how far is that exactly? ItБЂ™s almost beyond imagining. Space, you see, is just enormous-just enormous. LetБЂ™s imagine, for purposes of edification and entertainment, that we are about to go on a journey by rocketship. We wonБЂ™t go terribly far-just to the edge of our own solar system-but we need to get a fix on how big a place space is and what a small part of it we occupy. Now the bad news, IБЂ™m afraid, is that we wonБЂ™t be home for supper ...» |
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