1. Introduction To Modern Astronomy II
ASTR 113 – Spring 2006
Lecture May 3, 2006
Introduction To Modern Astronomy II
Review (Ch4-5): the Foundation
Sun, Our star (Ch18)
Nature of Stars (Ch19)
Birth of Stars (Ch20)
After Main Sequence (Ch21)
Death of Stars (Ch22)
Neutron Stars (Ch23)
Black Holes (Ch24)
Star (Ch18-24)
Our Galaxy (Ch25)
Galaxies (Ch26)
Active Galaxies (Ch27)
Galaxy (Ch 25-27)
1. Evolution of Universe (Ch28)
2. Early Universe (Ch29)
Cosmology (Ch28-29)
1. Extraterrestrial Life (Ch 30)
Extraterrestrial Life (Ch30)

2. The Search for Extraterrestrial Life
ASTR 113 – Spring 2006
Lecture May 3, 2006
The Search for Extraterrestrial Life
Chapter Thirty

3. Guiding Questions
What role could comets and meteorites have played in the origin of life on Earth?
Have spacecraft found any evidence for life elsewhere in our solar system?
Do meteorites from Mars give conclusive proof that life originated there?
How likely is it that other civilizations exist in our Galaxy?
How do astronomers search for evidence of civilizations on planets orbiting other stars?
Will it ever be possible to see Earthlike planets orbiting other stars?

4. Chemical building blocks of life
All life on Earth is based on carbon-based compounds, called organic molecules
These organic molecules occur naturally in the interstellar clouds of gas and dust throughout galaxies

5. A “Face” on Mars
Viking Orbiter, Mars Global Survey, 1998

6. Mars and Europa have the potential for life
Besides Earth, only two worlds in our solar system—the planet Mars and Jupiter’s satellite Europa—may have had the right conditions for the origin of life
Mars once had liquid water on its surface, though it has none today
Life may have originated on Mars during the liquid water era
Europa appears to have extensive liquid water beneath its icy surface

7. The Drake equation
Estimate how many civilizations may inhabit our Galaxy: about 10

8. SETI
SETI (search for extraterrestrial intelligence), an ongoing research for searching aliens
The search is best done in radio frequency between 1 to 10 Ghz, the so called water hole
Little noise
Little absorption by the Earth’s atmosphere; penetrate the atmosphere
Little interstellar extinction; penetrate the whole galaxy

9. What is the most exciting discover above all?