I Can Show You the Worlds: The Science of Planetary Exploration 4/18/2012

Introduction:

Earth is one of the eight planets in our Solar System. Within the past 20 years, astronomers have discovered more than 700 planets in the Universe, which are orbiting stars that are not our Sun. Presently, the Earth remains the only place in the Universe that we know of to harbor life. In this talk, we will discuss the possibility of life beyond Earth, as well as covering what we have learned about our own Solar System and the planets beyond.

Speakers:  

Anjali Tripathi is a first year graduate student in Astronomy at Harvard. With Dr. Ruth Murray-Clay, she uses computer simulations to study how an extrasolar planet can lose mass from its atmosphere when it is very close to its host star.

Kirit Karkare is a first year graduate student in Astronomy at Harvard. He works with Professor John Kovac on the design, deployment, and operation of radio telescopes at the South Pole. These telescopes observe the cosmic microwave background, looking for the signature of the physics that drove the birth of the universe.

Sukrit Ranjan is a second-year PhD student in astronomy. Working with Prof. David Charbonneau and Dr. Jean-Michel Desert, he works on using the Hubble Space Telescope to understand the composition of the atmospheres of planets around other stars. In his free time, he enjoys hiking, flying and reading.

Glossary

Biosignature:  An  indicator  for  life.  Excess  methane  in  the  presence  of  oxygen  is  considered  a  biosignature  for  life  on  Earth.  

Celsius:  A  temperature  scale.  0  C  corresponds  to  the  freezing  point  of  water  (32  F),  100  C  corresponds  to  the  boiling  point  of  water  (212  F).  

Doppler  Effect:  A  change  in  the  wavelength  of  light,  caused  when  the  source  of  light  is  moving.  

Extrasolar  planet  (exoplanet):  A  planet  orbiting  a  star  other  than  the  Sun.  

Galaxy:  A  system  of  billions  of  stars  held  together  by  gravity.    We  live  in  the  Milky  Way  Galaxy.  

Hematite:  A  type  of  mineral  that  contains  Iron  Oxide  found  on  both  Earth  and  Mars.  On  Earth,  it  can  be  formed  with  the  help  of  water,  such  as  at  the  bottom  of  a  lake,  or  with  the  help  of  volcanic  activity.  

Methane:  A  substance  found  on  Earth,  the  primary  component  of  natural  gas.  Sources  of  methane  include  volcanoes  and  biological  life.  Methane  is  very  flammable.  It  is  unstable  in  the  presence  of  oxygen.  

Orbit:  A  planet's  orbit  is  the  path  it  takes  around  its  host  star.  It  is  usually  circular.  More  generally,  an  orbit  is  the  path  any  object  takes  around  a  point  in  space,  due  to  gravity.  

Radial  Velocity:  The  speed  of  an  object  towards  or  away  from  us.    We  find  exoplanets  by  looking  at  how  the  radial  velocity  of  their  host  stars.  

Solar  System:  The  planets  orbiting  the  Sun:  Mercury,  Venus,  Earth,  Mars,  Jupiter,  Saturn,  Uranus,  Neptune.  Also  includes  the  moons  of  these  planets,  the  asteroid  belt,  and  the  comets.  

Spectrum:  The  rainbow  of  colors  that  is  visible  when  the  different  wavelengths  of  light  are  separated.  

Star:  An  object  composed  of  hydrogen  and  helium  that  gives  off  heat  and  light  due  to  nuclear  fusion.  Our  Sun  is  a  star.  

Transit:  When  a  planet  passes  in  front  of  a  star,  causing  the  total  light  to  dim.  

Wavelength:  A  measure  of  the  “color”  of  light.  Small  wavelengths  are  associated  with  blue,  hot  light.  Large  wavelengths  are  associated  with  red,  cool  light.  

Next Seminar (2nd May, 2012): Avian Flu and Scientific Censorship: When Should Scientists Keep their Mouths Shut?

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