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SUMMARY:Is the Earth Rare? - Jim Kasting (Penn State University)
DTSTART:20121108T163000Z
DTEND:20121108T173000Z
UID:TALK39703@talks.cam.ac.uk
CONTACT:Richard McMahon
DESCRIPTION:In their 2000 book\, Rare Earth\, Peter Ward and Don Brownlee 
 argue that complex life (i.e.\, animal life) is rare\, for a variety of re
 asons\, some of which are based on the idea that habitable planets are the
 mselves rare. Possible reasons for this include: 1) Plate tectonics (possi
 bly necessary to stabilize planetary climates) is rare\; 2) large moons (p
 ossibly necessary to stabilize planetary obliquities) are rare\; 3) magnet
 ic fields (possibly necessary to retain atmospheres) are rare\; 4) the Sun
  is anomalously metal-rich\; 5) Jupiter-sized outer planets (possibly nece
 ssary to protect the Earth from frequent large impacts) are rare. In my ta
 lk\, I will review these Rare Earth arguments and show that most\, or all\
 , of them are less troubling than Ward and Brownlee supposed. That said\, 
 there could be other factors not discussed by these authors that could mak
 e habitable planets scarce. But this should not discourage us from buildin
 g the types of large space telescopes required to actually answer this que
 stion.
LOCATION:Sackler Lecture Theatre\, IoA (tea at 4.00 pm)
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