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To: Telepathic Intruder

Plus:

i)plate tectonics (avoids the full globe resurfacing problem seen on Venus and an important part of magnetic field sustainability);

ii) low eccentricity orbit (i.e. mostly round);

iii) a Jupiter mass or larger companion to suck up rocks that would otherwise perpetually bombard the inner solar system;

iv) low variability in solar output; and

v) a quiet neighborhood where nothing big has gone supernova in the last billion years.


24 posted on 12/05/2011 11:42:22 AM PST by hc87
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To: hc87

Those are very good points. However, I have also imagined that there could be planets in which the conditions are even more favorable than here. Less asteroids in the system, for example. Or a star that has been ejected from its host galaxy by a merger. So although an extinction event occurs once every hundred million years or so here, and restarts evolution again almost from scratch, there are others that take much longer. Rare of course by a huge factor, but with more stars in the universe than there are grains of sand on the earth, it’s possible.


31 posted on 12/05/2011 12:14:46 PM PST by Telepathic Intruder (The right thing is not always the popular thing)
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