Introduction To Modern Astronomy II ASTR 113 – 003 Spring 2006 Lecture 14 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)

The Search for Extraterrestrial Life ASTR 113 – 003 Spring 2006 Lecture 14 May 3, 2006 The Search for Extraterrestrial Life Chapter Thirty

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?

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

A “Face” on Mars Viking Orbiter, 1976 Mars Global Survey, 1998

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

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

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

What is the most exciting discover above all?