Is  our  world  a  typical  product  of  planetary  formation  processes,  or  does  it  exhibit  an  un-­‐ usual  combination  of  properties  that  were  necessary  preconditions  for  the  emergence  of   life?  And  what's  the  strongest  influence:  Gaia  or  Goldilocks?  Does  a  complex  biosphere   self-­‐support  environmental  stability  or  does  this  confuse  cause  and  effect?

This  interdisciplinary  RAS  Discussion  Meeting  is  intended  to  shed  light  on  this  question   from  many  different  directions:  Cosmology  (How  big  is  the  Universe?),  Geophysics  (Is  the   Earth's  magnetic  field  unusually  strong?),  Biogeochemistry  (does  the  silicate  weathering   cycle  guarantee  climate  stability?),  Biology  (what  are  the  environmental  limits  on  a  com-­‐ plex  biosphere?),  Early-­‐life  (what  are  the  conditions  necessary  for  life  to  emerge?)  and   Celestial  Mechanics  (how  do  volatiles  get  to  terrestrial  planets?).    The  topic  is  highly  con-­‐ troversial  and  will  attract  speakers  and  attendees  from  both  sides  of  the  argument.

For further details please see RAS Events website

No registration necessary - simply arrive at the Geological Society, Piccadilly, for a 10am start.

Please click to view the abstract book for this meeting.

Is the Earth Rare?

Prof. James Kasting

(Penn State University)

5:30pm Thursday 8th December

Christopher Ingold LT, Chemistry dept., UCL

Public lecture, followed by wine reception and book signing

FREE to attend, but please register tickets at: www.eventbrite.com/event/2278312494

In their 2000 book, Rare Earth, Peter Ward and Don Brownlee argue that complex life (i.e., animal life) is rare in our galaxy for a variety of reasons, some of which are based on the idea that habitable planets are themselves rare. Possible reasons for this include: 1) Plate tectonics (possibly necessary to stabilize planetary climates) is rare; 2) large moons (possibly necessary to stabilize planetary obliquities) are rare; 3) magnetic fields (possibly necessary to retain atmospheres) are rare; 4) the Sun is anomalously metal-rich; 5) Jupiter-sized outer planets (possibly necessary to protect the Earth from frequent large impacts) are rare. In my talk, I will review these Rare Earth arguments and show that most, or all, of them are less troubling than Ward and Brownlee supposed. Despite this, perhaps there are other factors that could make habitable planets scarce. But this should not discourage us from building the types of large space telescopes required to actually answer this question.