Origin of Stars, Planets, and Life in the Universe

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The Origin and possible existence of Life in the
Universe
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Poll Question
Do you think there is life ? even just primitive
forms of life ? on other worlds?
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Do you think there is intelligent life on other
worlds?
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The Electromagnetic Spectrum
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Use a stamp X to select the most abundant
element in the universe.
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Axis of rotation
Approx. 1 light year
Axis of rotation
Rotation retards collapse in this direction
Gravity makes cloud shrink. As it shrinks it
spins caster and flattens into a disk with
central bulge.
Slowly spinning interstellar cloud
Approx. 100 AU
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Big Questions in Science
Questions about origins

• Where did we come from?
• Are we alone?

Other astrobiology questions

• How did life on Earth form?
• Should we expect life on many other worlds?
• Is life on other worlds like life on Earth?
• How can we detect life elsewhere?

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Poll Question What chemical elements were
created by the Big Bang?
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The Life Cycle of Stars
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CH4
H2
H2O
NH3
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Put a stamp on the most abundant element in
life on Earth.
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The Most Abundant Chemical Elements ? in the
Universe and in Life
In the Universe
In Life

• H
• He
• O
• C
• N

• H
• O
• C
• N

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A few facts about Life on Earth

• Life on Earth is carbon-based.
• Life on Earth requires liquid water
• The amino acids in life are easily formed.

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Finding Life

• First find planets. One way uses the Doppler
  Effect.

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• Another way to find planets is to look for
  transits.

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Kepler
Terrestrial Planet Finder
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Signs of Life (not yet possible to detect with
current technology)

• Seasonal changes
• Unusual abundances of gases
• Gases produced by life
• Unusual patterns of electromagnetic radiation
  (e.g., radio or TV broadcasts, the nighttime glow
  of cities)

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Bacterial fossils

• 3 billion years old on the earth.
• Will we find them on Mars or elsewhere?

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Records of Life on Earth

• Life elsewhere could be similar to any of
• These stages, or entirely different.

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Current Life Forms

• We can study these in detail to get DNA, etc.

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Amino Acids building blocks of life.

• Some of these were produced in the lab by Harold
  Urey out
• of primeval gases like methane, ammonia, carbon
  dioxide--by zapping them with electricity
  (lightning). (1950s)

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Human DNA

• Nobody has produced this
• artificially or even hopes
• to. Too complicated.
• 50,000 genes.
• However, the total makeup
• Of a human being requires
• More information.

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The distance between civilizations in the Milky
Way

• Nno.
• of civilizations.
• Rradius of
• spherical galaxy
• r average
• separation.
• 4 pi (r/2)2 N
• 4 pi R3/3
• implies
• r 2R/N1/3.

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The Drake Equation
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The Drake Equation

• N N fp ne fl fi fc fL
• N represents the number of stars in the Milky
  Way Galaxy
• Question How many stars are in the Milky Way
  Galaxy?
• Answer Current estimates are 100 billion.
• fp is the fraction of stars that have planets
  around them
• Question What percentage of stars have planetary
  systems?
• Answer Current estimates range from 20 to 50.
• ne is the number of planets per star that are
  capable of sustaining life
• Question For each star that does have a
  planetary system, how many planets are capable of
  sustaining life?
• Answer Current estimates range from 1 to 5.

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The Drake Eqn. continued

• N N fp ne fl fi fc fL
• fl is the fraction of planets in ne where life
  evolves
• Question On what percentage of the planets that
  are capable of sustaining life does life actually
  evolve?
• Answer Current estimates range from 100 (where
  life can evolve it will) down to close to 0.
• fi is the fraction of fl where intelligent life
  evolves
• Question On the planets where life does evolve,
  what percentage evolves intelligent life?
• Answer Estimates range from 100 (intelligence
  is such a survival advantage that it will
  certainly evolve) down to near 0.
• fc is the fraction of fi that communicate
• Question What percentage of intelligent races
  have the means and the desire to communicate?
• Answer 10 to 20

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The Drake Eqn. continued

• N N fp ne fl fi fc fL
• fL is fraction of the planet's life during which
  the communicating civilizations live
• Question For each civilization that does
  communicate, for what fraction of the planet's
  life does the civilization survive?
• Answer This is the toughest of the questions. If
  we take Earth as an example, the expected
  lifetime of our Sun and the Earth is roughly 10
  billion years. So far we've been communicating
  with radio waves for less than 100 years. How
  long will our civilization survive? Will we
  destroy ourselves in a few years like some
  predict or will we overcome our problems and
  survive for millennia? If we were destroyed
  tomorrow the answer to this question would be
  1/100,000,000th. If we survive for 10,000 years
  the answer will be 1/1,000,000th.
• N, the number of communicating civilizations in
  the galaxy.

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SETISearch for Extraterrestrial Intelligence

• Over 30 messages
• suspiciously intelligent.
• They are using home
• computers to scan for
• messages.

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Mars had ( and has) water.Does it have current
life?
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Summary

• We have learned an enormous amount about the
  origins of stars and planets.
• We are just starting to learn about life in the
  universe.
• These explorations require a team effort
  involving scientists from many disciplines.
• There is still much more to explore. Students
  will be able to make discoveries and help us
  learn even more!

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NASAs Navigator Missions http//planetquest.jpl
.nasa.gov/
Origins Education Forum http//origins.stsci.edu
/
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Poll Question Do you think there is life ? even
just primitive forms of life ? on other worlds?
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Do you think there is intelligent life on other
worlds?