Edmund Bertschinger

1
We are not aloneOther planets, other earths?

• Edmund Bertschinger
• MIT Department of Physics and
• Kavli Institute for Astrophysics and
• Space Research

2
(No Transcript)
3
Earth and Mars or Mars and Earth?
Mars is drier than the Atacama (or Sahara) desert.
4
Life on Mars?
R. Villard, STScI
5
Martian Meteorite found in Antarctica
Lunar and Planetary Institute
McKay et al. 1996 carbonate globules evidence
for microbial life?
6
(No Transcript)
7
Methane rivers and oceans on Titan (Huygens
lander, European Space Agency)
8
Family Portrait 4 rocky planets, 2 gas giants, 2
ice giants
9
(No Transcript)
10
Planets around other stars exoplanets After 10
years of study, 170 known (California-Carnegie
Planet Search, G. Marcy)
11
How to find other planetary systems

• Doppler measurement of stellar wobble planets
  gravity pulls on star

12
Figure from California-Carnegie Planet
Search First success 1995, Mayor and Queloz
13
How to find other planetary systems

• Transit planet passes in front of star, dims the
  light a tiny amount

14
Both the Doppler and Transit methods can much
more easily find close-in, Jupiter mass planets
than earth-like planets
15
How to find other planetary systems

• Infrared emission from dusty disks

16
(No Transcript)
17
How to find other planetary systems

• Direct imaging

18
(No Transcript)
19
How to find other planetary systems

• Gravitational Microlensing

20
Enhanced image at earth
The gravity of a planet orbiting a star causes
light rays to bend, changing the amount of light
reaching the earth.
Background star
25 January 2006 the star OGLE-2005-BLG-390L has
a planet of mass about 5 earth masses, in a
10-year orbit!
21
Family Comparison
22
Family Comparison
R. Villard, STScI
23
What have we learned?
At least a few percent of sunlike stars have
massive planets
24
What have we learned?
Surprise Hot Jupiters on wildly eccentric
orbits (California-Carnegie Planet Search)
25
What have we learned?
Stars with more heavy elements are more likely to
host planets (California-Carnegie Planet Search)
26
What have we learned?
Some planets likely have right conditions for
liquid water (its 300K in here!)
27
Habitable zone for life
Darren Williams, Penn State Erie
28
Habitable zone for life
Darren Williams, Penn State Erie
29
Future search for earthlike planets and life
Kepler 2008 launch scheduled Search method
transits European Corot mission may scoop US.
Terrestrial Planet Finder 2015 or
later Atmospheric Spectroscopy
30
Additional Credits and Information

• Credits
• Water on Mars antwrp.gsfc.nasa.gov/apod/ -
  Astronomy Picture of the Day
• Sahara Desert and Mars Lunar and Planetary
  Institute
• Hubble detects a transiting planet and Beta
  Pictoris images Space Telescope Science
  Institute
• Black hole embedding diagram Scott Hughes, MIT
• Figures showing Mean Orbital Distance created
  online at http//extrasolar.net/charts.asp
• Kepler and TPF NASA/Jet Propulsion Laboratory
• Books
• Origins Fourteen Billion Years of Cosmic
  Evolution, Neil deGrasse Tyson and Donald
  Goldsmith
• Earth An Intimate History, Richard Fortey
• The Ancestors Tale A Pilgrimage to the Dawn of
  Evolution, Richard Dawkins

31
Websites for more information

• Extrasolar.net General information about
  exoplanets
• Exoplanets.org California-Carnegie exoplanet
  searches
• www.astrobio.net - Astrobiology
• Solstation.com General astronomy information,
  sky maps
• antwrp.gsfc.nasa.gov/apod/ - Astronomy Picture of
  the Day