September 7, 2009 | David F. Coppedge

Earth Size Gives Life Edge

The earth seems to be holding onto its status as a privileged planet.  New Scientist reported that a rocky planet’s size is linked to its ability to sustain a magnetic field and plate tectonics.  This means that some of the “super-earths” found around other stars (5-10 times the size of earth) may not be habitable.  Vlada Stamenkovic (German Aerospace Center) will be presenting these ideas this month at the European Planetary Science Congress.
    Astrobiologist David Grinspoon disagrees with the constraint on planet size being crucial for life.  While plate tectonics removes excess carbon dioxide, stabilizing earth’s atmosphere and climate, “the possibility that other forms of crustal recycling on super-Earths might do so should not be ruled out.”  But the example he gave is Venus, which is neither habitable, nor has a stable climate, nor a magnetic field.  This suggests that planet size is a necessary but not sufficient condition for habitability.  The article did not say whether he has an answer for the claim that large rocky planets would be unable to generate a magnetic field.

You can watch The Privileged Planet in segments on YouTube.  None of the factors listed that support life on earth has been shot down, though there has been some dispute about the role of Jupiter deflecting debris.  In addition, the finding that most stars are small (see JPL feature) promotes our sun to a privileged few.  The film goes beyond just the lucky coincidences.  It discusses additional philosophical and evidential material that must cause a thoughtful observer to ponder our place in the universe.  In the 1980s, Carl Sagan made it popular to think of the earth as an insignificant speck, lost in space.  That mood has changed in the intervening years as more discoveries highlight the combination of multiple, independent, surprising factors that came out just right on our home base.
    These findings are not surprising to Bible believers.  Isaiah the prophet said God did not make the earth in vain, but formed it to be inhabited (45:18).  Isaiah also rightly stated that earth is a sphere and that its inhabitants are as puny as insects and dust from God’s perspective (read Isaiah 40-45).  He also emphasized, though, that humans are more than mere dust.  God gives to each of them breath and spirit (42:5), and offers salvation to the humble (45:5-10, 21-22) and strength to the weary (40:28-31).

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