Transcript Life in the Universe

Life in the Universe
029:062 Guest Lecture
Catherine Whiting
Life in the Universe
• What are the chances of extraterrestrial life in
the universe?
– How common are extrasolar planets?
– How many of these planets are suitable for life?
(at least earth-like life)
– What characteristics would this life possess?
– How would we make contact?
Extrasolar Planets
• Detection Methods
Extrasolar Planets
• Detection Methods
– Eclipses
Extrasolar Planets
• Detection Methods
– Doppler Shifts – planet causes star to wobble
Extrasolar Planets
• Detection Methods
– Imaging
HR 8799 Infrared
Image
Planets only 60
million years oldstill glowing from
formation
Extrasolar Planets
• Detection Methods
– Eclipses, Doppler Shifts, Imaging
– Subject to selection effects- meaning we tend to
detect mostly Jupiter-like planets that are close to
their stars because our detection methods are
best-suited to detecting Jupiter-like planets
– Earth-like planets now being detected - Kepler
Mission
Example: Gliese 581
• Red dwarf star
• 20.3 light years
away
• At least 6 known
planets- some
could support life
Habitable Zone
• Life on Earth appears to require water
• Planets with water may be the most promising
places for life
• In order to have liquid water, the temperature
of the planet must be between freezing and
boiling points
• This limits its distance from its star- Habitable
Zone-
Habitable Zone
More than 450 new planets have been
discovered since 1995
99% of all organic material consists of 4
elements: Hydrogen, Carbon, Oxygen, Nitrogen
Chemical Abundances in Stars
Ammonia, Methane, Water + Lightning= Amino Acids !
Miller-Urey Experiment
• Cosmos Episode 2: time: 46:15
• http://www.youtube.com/watch?v=p1Zh69TB
0lU
Drake Equation
• Carl Sagan Video:
• http://www.youtube.com/watch?v=MlikCebQ
SlY&feature=related
• Carl Sagan translated for rednecks:
• http://www.youtube.com/watch?v=DI9ImScQ
GAo&feature=related
What would aliens look like?
• Cosmos Episode 2: time: 52:50
http://www.youtube.com/watch?v=p1Zh69TB0l
U
Discussion Questions
• Would alien civilizations be hostile?
• Are aliens already secretly here?
– Colonization, government conspiracy
– Would we even be able to comprehend them?
SETI (Search for ExtraTerrestrial
Intelligence)
• If there are other civilizations out there, are they trying to
contact us?
• There are active searches for ET signals, mainly in the radio,
some using visible light.
Arecibo Message
Voyager
Voyager Decoded
Voyager Message
• http://voyager.jpl.nasa.gov/spacecraft/index.h
tml
Discussion Questions
• If we were to send another Voyager or Arecibo
message, what would you include?
– Instruments?
– Music?
– Videos?
– Sounds?
– Information?