1. ASTR368 Exoplanet Detections

3. Kepler

9. Life in the Universe (Chapter 24) Extra-Solar Life http://grooveshark.com/s/Is+There+Anybody+ Out+There/541wYk?src=5

10. Other Possible Necessities for Life A large planet like Jupiter to clear out asteroids? A large moon? A magnetosphere? The right location in a Galaxy?

11. Impacts and Habitability Some scientists argue that Jupiter-like planets are necessary to reduce rate of impacts If so, then Earth-like planets are restricted to star systems with Jupiter-like planets

12. Climate and the Moon The planet should spin relatively quickly so day/night temperatures aren’t too dramatically different The Earth has an unusually large Moon Tidal pools are ultimately caused by the Moon and may be necessary for life

13. Magnetospheres Magnetosphere protects a planet from a stellar wind, which may disrupt formation of life

14. Constraints on Galaxy Location Some scientists argue that proportions of heavy elements need to be just right for formation of habitable planets If so, then Earth-like planets are restricted to a Galactic habitable zone

15. The Drake Equation How likely is this process? How special is the Earth? Frank Drake

16. The Drake Equation R * is the average rate of star formation in our Galaxy f p is the fraction of those stars that have planets n e is the average number of planets that can support life f ℓ is the fraction of the above that develop life at some point f i is the fraction of the above that develop intelligent life f c is the fraction of civilizations that develop a technology that releases detectable signs of their existence into space L is the length of time such civilizations release detectable signals into space. How likely is this process? How special is the Earth?

17. The Drake Equation (simplified) Number of civilizations with whom we could potentially communicate N = N HP  f life  f civ  f now N HP = total # of habitable planets in galaxy f life = fraction of habitable planets with life f civ = fraction of life-bearing planets w/ civilization at some time f now = fraction of civilizations around now.

18. We do not know the values for the Drake Equation N HP : probably billions. f life : ??? Hard to say (is it near 0 or near 1?) f civ : ?????? It took 4 billion years on Earth f now : ?????? Can civilizations survive long-term?

19. What are we Doing to Find E.T.? 1)Space probes! 2)SETI searches 3)Locating extrasolar planets But we’re not really trying too hard, all things considered

20. Voyager 1+2, Pioneer 10+11 launched in the 1970s and still going Spacecraft take about 100,000 years to reach the nearest stars. http://voyager.jpl.nasa.gov/spacecraft/goldenrec.html Pioneer plaqueVoyager record Space Probes

21. New Horizons To infinity and beyond!

22. The Search for ExtraTerrestrial Life (SETI) SETI searches the sky at radio frequencies for strong, repeating signals IN OUR GALAXY Nothing plausible so far….

23. SETI @ Home

24. We have even Sent a few Signals Sent from Arecibo Telescope in 1974 to globular cluster M13 by Frank Drake, Carl Sagan and others

25. Fermi’s Paradox Plausible arguments suggest that civilizations should be common, for example: Even if only 1 in 1 million stars gets a civilization at some time  100,000 civilizations So why we haven’t we detected them?

26. Solutions to Fermi’s Paradox 1) We are alone: life/civilizations much rarer than we might have guessed. Our own planet/civilization looks all the more precious… 2) There are lots of other civilizations but lots of stars. Someday we’ll meet them.

27. Anthropic Principle The Universe appears to be fine-tuned for life (us). If the parameters of the Universe (e.g., the force of gravity) were only slightly different, stars and galaxies would not form, and we would not be here. The Anthropic Principle states that the Universe appears fine-tuned to us, because we are here to observe it. If we were not here, there would be no one to report on whether the Universe is fine-tuned or not.

28. Anthropic Principle Modified anthropic principle (Schmidhuber): The 'problem' of existence is only relevant to a species capable of formulating the question. Prior to Homo sapiens' intellectual evolution to the point where the nature of the observed universe - and humans' place within same - spawned deep inquiry into its origins, the 'problem' simply did not exist.