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Astronomy 251 Life on Other Worlds Mondays 4-6, MP102 Prof. Ray Jayawardhana MP 1408 416 946 7291 rayjay@astro.ut

Astronomy 251 Life on Other Worlds Mondays 4-6, MP102 Prof. Ray Jayawardhana MP 1408 416 946 7291 rayjay@astro.utoronto.ca Office hours: Tuesdays 11-12 or by appt. Course website and syllabus: http://www.astro.utoronto.ca/~rayjay/ast251 Astronomy 251 Life on Other Worlds TAs:

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Astronomy 251 Life on Other Worlds Mondays 4-6, MP102 Prof. Ray Jayawardhana MP 1408 416 946 7291 rayjay@astro.ut

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  1. Astronomy 251 Life on Other Worlds Mondays 4-6, MP102 Prof. Ray Jayawardhana MP 1408 416 946 7291 rayjay@astro.utoronto.ca Office hours: Tuesdays 11-12 or by appt. Course website and syllabus: http://www.astro.utoronto.ca/~rayjay/ast251

  2. Astronomy 251 Life on Other Worlds TAs: Parandis Khavari khavari@astro A-G Tim Rothwell rothwell@cita H-N Marija Stankovic stankovic@astro P-Z

  3. Course Textbook Goldsmith & Owen The Search for Life in the Universe

  4. Latest news… Planetary debris disks around young Sun-like stars

  5. Latest news… Cassini at Saturn (NASA/ESA joint mission) Titan close-up: “Xanadu” and clouds layers of haze in Titan’s upper atmosphere

  6. Latest news… Cassini at Saturn Huygens probe released December 25 Will arrive at Titan January 14, and (hopefully!) descend through its thick, smoggy atmosphere

  7. Latest news… Mars Express (ESA) continues mapping the red planet Olympus Mons and a stereo view of its caldera Evidence of lava flows within the past two million years… Could some volcanoes be dormant rather than dead?

  8. Latest news… Receding glaciers in Alaska Comparison with photos taken as far back as 1883 Of a thousand glaciers in Alaska, only 15 are still growing; rest are stagnant or melting dramatically Likely culprit: general warming by at least 1.5o C in the 20th century Toboggan glacier: in 1909 and 2000

  9. Latest news… Microbes deep under the ocean floor New evidence of microbe communities as much as 0.5 km below the ocean floor (core samples taken off Peru in the Pacific Ocean) These microbes seem to rely ultimately on oxygen and organic matter produced by photosynthesis

  10. Speculation on Extraterrestrial Life In religion… Veddaculture (indigenous to Sri Lanka) After death, souls migrate to the Sun, the Moon, and the stars. ChurchofLatter-DaySaints (Mormon Church) Souls move to the celestial kingdom; the worthy create new worlds.

  11. Speculation on Extraterrestrial Life Early scientific speculation… Greek philosophers Both Materialists and Idealists held that life extended beyond Earth. c. 600 BCE Thales of Miletus (first Greek philosopher?) The Earth and stars are made of the same material. c. 450 BCE Anaxagoras The Moon is inhabited.

  12. Speculation on Extraterrestrial Life Epicurian school introducespanspermia: “ubiquitous life” c. 400 BCE Metrodorus of Chios (atomist; student of Epicurus) “It is unnatural in a large field to have only one shaft of wheat and in the infinite universe only one living world.” c. 50 BCETitus Lucretius Carus "Nothing in the universe is unique and alone, and therefore in other regions there must be other Earths inhabited by different tribes of men and breeds of beasts."

  13. Speculation on Extraterrestrial Life c. 1590Giordano Bruno (Italian monk) “Innumerable suns exist; innumerable earths revolve around these suns in a manner similar to the way the seven planets revolve around our sun…” inDe l'Infinito , Universo e Mondi Burned at stake for his heretical beliefs on February 17, 1600 in Rome

  14. Speculation on Extraterrestrial Life 1750-1830: speculations by writers (de Bergerac, Voltaire,Lomonosov), philosophers (de Fontenelle, Kant), & scientists (Laplace, Herschel, Huygens, Gauss) on panspermia. Herschel: Thinks Sun is inhabited (also held byNewton!) 1820: Karl Gausssuggestsplanting trees in a right triangle, demonstrating the Pythagorean Theorem to Martians. 1840:Joseph von Littrowsuggests kerosene-filled trenches instead. 1853: A caution on habitability: William Whewell outer planets – “water, gases, and vapour” inner planets – “hot water” on surfaces due to proximity to Sun

  15. Speculation on Extraterrestrial Life c. 1870: Cammille Flammarion writes On the Plurality of Habitable Worlds. 1896: Konstantin Tsiolkovskiy (early rocket scientist) extraterrestrials may be at different stages of development. 1899:Nikola Teslasends out burst of radio noise, listens for a reply. Tesla Marconi Lowell Edison

  16. Speculation on Extraterrestrial Life c. 1900: Svante Arrhenius (Swedish chemist): Suggests that spores travel among worlds, seeding life.

  17. Speculation on Extraterrestrial Life 1869: Secchi (Italian Astronomer)sees “canali” on Mars. 1877: Schiaparellidescribes seasonal variation in “canali” 1900: Percival Lowellsuggests “canals” are large-scale engineering structures and extrapolates an entire culture.

  18. Speculation on Extraterrestrial Life 1922G. Marconi listens for radio signals from a boat in a remote oceanic location. 1960s - now:Fred Hoyle (deceased), N.C. Wickramsinghe argue life – including infectious diseases viruses – fall on Earth from space. 2003… BBC

  19. Big Questions Class poll...

  20. Big Questions • How did life begin and evolve here on Earth? • Does life exist elsewhere in the Universe? • What is life’s future, on Earth and beyond?

  21. Big Questions • Understand how life arose here • Determine the principles governing the organization of matter into living systems • Explore how life evolves on the molecular, organism, and ecosystem levels • Determine how the biosphere co-evolves with the Earth • Establish limits for life in environments that provide analogues for conditions on other planets • Determine what makes a planet habitable and how common these worlds are • Determine how to recognize the signature of life on another planet • Determine if there ever was or even is life elsewhere in the Solar System – especially on Mars, Europa, or Titan

  22. Big Questions How many stars & planets? How far apart? What makes a place hospitable to life? What do we learn about other worlds from our own history? What is life? How did it come about? How does life affect its environment? How does complex life evolve? ...or intelligence? Did life begin on Earth or did it come from elsewhere? Did life start here only once? How long will it last? How many intelligent civilizations are within earshot? ...or within reach? Is the Galaxy colonized? Where is everybody?

  23. Astrobiology & Bioastronomy Geology Geophysics Biology Astronomy Prebiotic Chemistry Alternate Biochemistry Formation of Life Evolution & Adaptation Limits of Life Habitability Cosmology Galaxy Evolution Star Formation Interstellar Medium Astrochemistry Stellar Evolution Planet Formation Planetary Dynamics Earth/Moon System Impact History External Hazards Search for Extraterrestrials Creation of Crust Origins of Oceans Oxygen Atmosphere Geothermal Heat Plate Tectonics CO2 – Silicate Cycle

  24. Course Overview Origin of the Universe, Stars, and Planets Introduction to our Galaxy Stellar Evolution and Creation of the Elements Formation and early evolution of Earth Geological evolution of Earth Beginnings of life on Earth Life in extreme environments Habitable environments in the Solar System Habitable environments and life in the Galaxy Interstellar communication Interstellar travel Colonization of the Milky Way?

  25. Grading 15% Participation 25% Midterm Exam 30% Research Paper 30% Final Exam

  26. Research Paper Topic suggestions available on website Jan 31: statement of intents due 1 week later: projects should be approved Feb 28: paper outline due Mar 14: paper itself due

  27. Who's out there? Drake's Equation (1961 Green Bank meeting) An estimate of the number of inhabited, communicating planets in the Galaxy N = R * fs * fp * ne * fl * fi * fc * L

  28. Who's out there? Drake's Equation N = R * fs * fp * ne * fl * fi * fc * L Number of stars in the Galaxy: 1011 Lifetime of Galaxy: 1010 years 1011 stars/1010 years ~ 10 stars/year Star birth rate…

  29. Who's out there? Drake's Equation N = R * fs * fp * ne * fl * fi * fc * L Fraction of Sun-like stars 1961 view: fs ~ 1/10

  30. Who's out there? Drake's Equation N = R * fs * fp * ne * fl * fi * fc * L Fraction of stars with planets D.Durda 1961 view: fp ~ 1/2 Principle of Mediocrity

  31. Who's out there? Drake's Equation N = R * fs * fp * ne * fl * fi * fc * L Number of Earth-like planets per extra-solar system 1961 view: ne ~ 1 Again, Principle of Mediocrity

  32. Who's out there? Who's out there? Drake's Equation N = R * fs * fp * ne * fl * fi * fc * L Fraction of Earth-like planets on which life arises 1961 view: fl ~ 1 Yet again, Principle of Mediocrity … plus a look at our own past

  33. Who's out there? Drake's Equation N = R * fs * fp * ne * fl * fi * fc * L Fraction of biospheres that develop an intelligent species 1961 view: Some intelligence is a good survival trait. So perhaps fi ~ 1

  34. Who's out there? Drake's Equation N = R * fs * fp * ne * fl * fi * fc * L Fraction of intelligent species that develop technological civilizations and want to communicate

  35. Who's out there? Drake's Equation N = R * fs * fp * ne * fl * fi * fc * L Fraction of intelligent species that develop technological civilizations and want to communicate 1961 view: fc ~ 1/5

  36. Who's out there? Drake's Equation N = R * fs * fp * ne * fl * fi * fc * L Typical lifetime of technological civilizations…

  37. Who's out there? Drake's Equation N = R * fs * fp * ne * fl * fi * fc * L Typical lifetime of technological civilizations…

  38. Who's out there? Drake's Equation N = R * fs * fp * ne * fl * fi * fc * L N ~ 10/year * 1/10 * 1/2 * 1 * 1 * 1 * 1/5 * L years N ~ L/10

  39. L ~ 50 yr

  40. L ~ 109 yr

  41. To those everywhere who seek to make a large number…. -Walter Sullivan dedication in We are Not Alone (1970)

  42. Preview of Lecture 2

  43. Any questions?

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