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Search for Life: Extrasolar Planets by Robert Nemiroff Michigan Technological University Physics X: About This Course • Officially "Extraordinary Concepts in Physics" • Being taught for credit at Michigan Tech o Light on math, heavy on concepts o Anyone anywhere is welcome • No textbook required o Wikipedia, web links, and lectures only o Find all the lectures with Google at: "Starship Asterisk" then "Physics X" o http://bb.nightskylive.net/ o asterisk/viewforum.php?f=39 Search for Extrasolar Planets If life exists outside of Earth, it is likely on a planet. • How common are planets around stars? • How common are rocky planets? • How common are planets in the habitable zone? o where liquid water can exist • How common is water? • How common are biomarkers? Search for Extrasolar Planets Hot topic in modern astronomy. Main techniques: • slight changes in pulsar timings o civilizations unlikely there (?) but read Dragon's Egg by R. Forward • slight doppler wobble of star due to planets o most planets now found this way • slight occultation of planet by star o Kepler satellite will likely find thousands • gravitational lensing o once and done, but can see low mass planets • direct image of planet o hard since parent star so bright 55 Cancri: Familiar Planet Discovered Illustration Credit & Copyright: Lynette Cook APOD: 2002 June 14 Water Claimed in Evaporating Planet HD 209458b Illustration Credit: ESA, A. Vidal-Madjar (IAP, CNRS), NASA APOD: 2007 April 17 A Dangerous Sunrise on Gliese 876d Illustration Credit & Copyright: Inga Nielsen (Hamburg Obs., Gate to Nowhere) APOD: 2008 May 21 HR 8799: Discovery of a Multi-planet Star System Credit: C. Marois et al., NRC Canada APOD: 2008 November 17 Kepler's Streak Credit & Copyright: Ben Cooper APOD: 2009 March 9 CoRoT Satellite Discovers Rocky Planet Illustration Credit: ESO/L. Calcada APOD: 2009 September 23 A Giant Planet for Beta Pic Credit: A.-M. Lagrange, D. Ehrenreich (LAOG), et al., ESO APOD: 2010 July 3 Companion of a Young, Sun-like Star Confirmed Credit: Gemini Observatory, D. Lafreniere, R. Jayawardhana, M. van Kerkwijk (Univ. Toronto) APOD: 2010 July 4 Zarmina's World Illustration Credit & Copyright: Lynette Cook APOD: 2010 October 1 Kepler's First Five Exoplanets (Wikipedia) Planets around Alpha Centauri? RJN comment: The Alpha Centauri system is the closest star system to the Sun, and contains a star very much like our Sun. Does this star have planets? We currently don't know. We should try harder to find out! At 4.3 light years distant, it might be a good far future outpost for humans.