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Earth may have lost "twin" supporting life

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  • stig.agermose@xxxxxxx.xxxxxxxxxxxxxxxxx)
    Source: The Nando Times, http://www.nandotimes.com/noframes/story/0,2107,65700-104076-740333-0,00.html Stig *** Scientist says Earth may have a long-lost
    Message 1 of 1 , Jun 30, 1999
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      Source: The Nando Times,

      http://www.nandotimes.com/noframes/story/0,2107,65700-104076-740333-0,00.html

      Stig

      ***

      Scientist says Earth may have a long-lost 'twin'

      Copyright �1999 Nando Media
      Copyright �1999 Associated Press

      By WILLIAM McCALL

      (June 30, 1999 4:02 p.m. EDT http://www.nandotimes.com) - Somewhere in
      deep, dark space, Earth may have a lost "twin" capable of supporting
      life, an astronomer says.

      In a theory outlined in Thursday's issue of the journal Nature, David
      Stevenson of the California Institute of Technology says Earth may
      have had one or more siblings when the solar system was born, but they
      were jettisoned by gravity when they got too close to Jupiter or other
      large planets.

      The idea has been around for a while. But Stevenson goes a step
      further, drawing on planetary theory and his own calculations to argue
      that these Earth-like planets may be capable of supporting life,
      despite their wanderings through the cold, dark void, far from the
      sun.

      "Life would have to be simple," he said. "Certainly you wouldn't have
      much of it."

      He said these planets may be heated by a dense hydrogen atmosphere and
      volcanoes, instead of sunlight. The combined heat could be enough to
      sustain warm oceans, which could nourish the formation of life.

      "It's really a very logical conclusion from what we know about planet
      formation," said Alan Boss of the Carnegie Institution in Washington,
      one of the leaders in the search for other solar systems.

      No one has ever actually found one these so-called rogue planets.
      Nevertheless, there could be millions, even billions, of them roaming
      the galaxy in the dark, carrying water and simple life, Stevenson
      said.

      Other scientists agree there is little doubt that planets were ejected
      from the primordial solar system. But they are unsure whether these
      bodies have the atmosphere and other means to sustain even simple
      life.

      "Just because you can make an atmosphere doesn't mean you can keep
      it," said Jonathan Lunine at the University of Arizona. "You have to
      ask whether that atmosphere, when perturbed very slightly, would
      return to its regular state or just collapse onto the surface."

      Stevenson said that rogue planets could have clouds and even
      lightning, but not the constantly shifting weather on Earth that is
      largely driven by sunlight.

      "The temperature would be very uniform from place to place. It would
      be a dull place in that sense, and of course it would be totally
      dark," he said.

      The possibility of actually finding a rogue planet is very small
      indeed, scientists agreed.

      "It's like finding a grain of sand inside the Earth," Boss said.


      Copyright �1999 Nando Media
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