February 9, 2006 | David F. Coppedge

SETI Tries to Stretch the Habitable Zone

Can life exist outside the circumstellar habitable zone, that ring of life around a star where the temperature is comfy?  “For more than 150 years,” Ker Than wrote for LiveScience, “…this zone has been defined as a narrow disk around a star where temperatures are moderate enough that water on the surface of a planet can exist in a liquid form.”  His article surveyed newer, more optimistic ideas that extend the zone of life into dark, distant regions beyond.
    The reasoning is based on three findings:

  1. Extreme life: Extremophiles can live on earth in places long thought inhospitable.
  2. Warm moons: Enceladus and Europa provide examples of locations outside the zone that may be warm enough for water.
  3. More of less: A red dwarf star’s habitable zone may be small, but there are so many of them (85% of stars), they add up.

Ker Than acknowledged that the zones around red dwarfs would be so close-in, any planet would become tidally locked – hot on the lit side, freezing on the dark side.  But he claimed that new models “predict that if an orbiting planet had a thick enough atmosphere, heat could be redistributed from the lit side of the planet to the side that was dark.”
    Some of these ideas came from a conference last fall sponsored by the SETI Institute, where about 30 scientists discussed whether planets orbiting red dwarf stars could be habitable. 

The Maybe Babies squeal with delight when they get their water bottle.  Water is nice, water is wet, water is necessary.  Water is not sufficient.  Like Jay Richards explained in The Privileged Planet, there is more to getting a habitable planet than “just add water.”  See the film for a long list of requirements that will dampen false hopes for life without design.

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