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Planets That Harbour Life May Be Roaming Interstellar Space

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  • stig.agermose@xxxxxxx.xxxxxxxxxxxxxxxxx)
    Source: http://news.bbc.co.uk/low/english/sci/tech/newsid_382000/382319.stm Stig *** BBC News Online: Sci/Tech Thursday, July 1, 1999 Published at 05:02 GMT
    Message 1 of 1 , Jun 30, 1999
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      Source:

      http://news.bbc.co.uk/low/english/sci/tech/newsid_382000/382319.stm

      Stig

      ***

      BBC News Online: Sci/Tech

      Thursday, July 1, 1999 Published at 05:02 GMT 06:02 UK

      Life lost in space

      **

      Planets that could harbour life may be roaming the voids of
      interstellar space, according to a report in Nature magazine.

      Planetary scientist David Stevenson thinks it is possible that rocky
      masses the size of the Earth are ejected from solar systems as they
      form - kicked out by the gravitational effects of much larger planets.


      However, even without the energy supplied by sunlight, he believes
      these nomadic worlds could still maintain the conditions necessary for
      life.

      Mr Stevenson, of the California Institute of Technology, says the
      ejected planets would possibly carry with them an atmosphere of
      hydrogen. This could act to trap any internal heat. It may even exert
      enough pressure to maintain oceans of liquid water on the planet's
      surface.

      With ammonia and methane gases in the atmosphere, and volcanoes
      bubbling heat and molten rock to the surface, these lonely planets
      would look remarkably similar to the Earth when life began here some
      four billion years ago.


      Alternative energy


      All these planets would lack is the energy supplied by a sun.

      Writing in Nature, Mr Stevenson says: "If life can develop and be
      sustained without sunlight (but with other energy sources, plausibly
      volcanism or lightning in this instance), these bodies may provide a
      long-lived, stable environment for life (albeit one where the
      temperatures slowly decline on a billion-year timescale).

      "The complexity and biomass may be low because the energy source will
      be small, but it is conceivable that these are the most common sites
      of life in the universe."

      Oceans on the nomadic planets would have surface pressures and
      temperatures similar to those found at the bottom of the Earth's
      oceans, places where we know life can exist, thriving on the heat and
      nutrients supplied from hot water vents.

      Mr Stevenson's ideas are controversial but it will be virtually
      impossible to test them. Despite emitting some degree of radiated
      heat, and possibly radio waves, the planets would be almost invisible.


      Artist's impression of a developing solar system taken from the BBC
      Science TV series The Planets.


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      Internet Links:

      *Nature


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