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Rodman Seminar Sep 27, 2005

Rodman Seminar Sep 27, 2005 . Today: Intro. Life: On Earth, in Solar System, or Elsewhere. Solar System. (objects are to scale, distances aren’t). The Galaxy. NGC4414  (Similar to our Galaxy). Milky Way schematic. Jewel Box Cluster. Naked eye stars. Eagle Nebula. Crab

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Rodman Seminar Sep 27, 2005

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  1. Rodman Seminar Sep 27, 2005 Today: Intro. Life: On Earth, in Solar System, or Elsewhere

  2. Solar System (objects are to scale, distances aren’t)

  3. The Galaxy NGC4414  (Similar to our Galaxy) Milky Way schematic

  4. Jewel Box Cluster Naked eye stars Eagle Nebula Crab Nebula Our Galaxy Earth = 100 nm = virus Sun = 10 μm = cell Earth orbit = ¼ cm = pin head Solar system = 20 cm = saucer Nearest star = 250 m = lawn Solar system Galaxy Center

  5. Universe

  6. Scales Distances: Within Solar System: 1 Astronomical Unit (AU)  8.5 light-minutes Between stars: Parsecs (pc)  3.3 Light years (ly)  200,000 AU Size of Galaxy: 100 kilo-parsecs (kpc) Between Galaxies: several mega-parsecs (Mpc) Time: Age of Universe: ~ 13 Gyr Age of Sun/Earth: ~ 4.5 Gyr

  7. Life Any practical definition that covers microbes to more complex organisms. Aside issues: Life is of a type we’d recognize. Given pre-biotic organics, some way to get ‘life’. Evolution works: life  intelligent life. ??

  8. Life on Earth 0 1 2 3 4 4.5 Life on land Stromatolites: (bacteria colonies) First multi-celled organisms Billions of Years Ago Origin of life Formation

  9. Life on Earth 0 1 2 3 4 4.5 Life on land Arose quickly: Inevitable or chance occurrence? Hardy: Survived large impacts. Found everywhere: thermal ocean vents under ice sheets km below the surface Billions of Years Ago Origin of life Formation

  10. Earth clues 0 1 2 3 4 4.5 Life on land • 1st single cells about 3.5 Byr ago • 1st multi-celled organisms about 700 Myr ago • 1st intelligence about 1 M to 10,000 years ago (?) What do these times imply about likelihood/ease of life developing? Billions of Years Ago Origin of life Formation

  11. Intelligence Definition = technology. On Earth: • At least one species • Several almost there • Most not there If intelligent life elsewhere, • Where to look? • What to look for? Is intelligence likely or unlikely? What factors are important?

  12. Endogenic? Early Earth: “Primordial soup” Reducing environment: methane, ammonia, hydrogen, water, + ??? Evidence: geologic chemical signatures cyano-bacteria earliest life Energy sources for life available. Tracing RNA  suggests hydrothermophile origin (>100o C) ? ? ?

  13. Endogenic? Urey – Miller Experiment (1953) • Simulated “Primordial soup” methane, ammonia, hydrogen, water • Add energy:  electrical discharges • Formed organic compounds such as amino acids. • Not life, but possible precursors. • Controversial. Amino acid Glycine

  14. Titan Natural Urey-Miller experiment: Titan Nitrogen + Methane (CH4) atmosphere + solar UV light = organic molecules

  15. Exogenic? What if initial building blocks came from elsewhere? Murchison Meteorite Australia, 1969 Contained amino acids First “carbonaceous chondrite”

  16. Exogenic? Interstellar Medium (the ISM) Signatures of many organic compounds: PAHs Formaldehyde Glycine? Sugars

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