SETI Researchers Affirm Planetary Privilege Criteria

In the weekly SETI Thursday column on Space.com, Douglas Vakoch corroborated two claims made about the habitability of planets in the film The Privileged Planet (shown at the Smithsonian last night – see 06/09/2005 story): namely, (1) smaller stars have smaller habitable zones or “Goldilocks” zones where life can exist, and (2) planets within the habitable zone of a small star are closer in, tending to tidally lock one face toward the star – reducing the chance for habitability.  They admitted even more, that such conditions (if an atmosphere existed) would “whip up enormous wind velocities.”  They balanced that bad news with hopes that such worlds might have enough greenhouse effect to moderate the winds.  Since the discovery of Gliese 876, the smallest extrasolar planet so far, astrobiologists and SETI researchers are taking a second look at smaller M-class stars as homes for habitable planets.  None of the ones surveyed so far has a Jupiter-class planet, so the thinking is that most planets might be small rocky worlds around small, warm stars.

How much hoc can an ad hoc hawk for an ad hoc post hoc post?  An M-class star needs a Jupiter for its comet shield, remember?  And is intelligent life going to thrive on the dark side of a tidally locked world in time to build a flashlight, let alone a radio telescope?  Or is it going to bake in its sun forever on the lit side and never see the stars, dreaming of who else is out there?  Maybe there is a thin great circle on its twilight zone suitable for life.  Don’t count on a booming economy, though.
    Don’t expect sitcoms or even kid fare on the M channel.  If Goldilocks had to broadcast from such a world she would move to a nicer zone.  Like the film suggests, that leaves out 90% of the market.