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Habitable Terrestrial Exoplanet. Search for terrestrial planets around M dwarfs → larger reflex motion Smaller stellar mass Habitable zone closer (<0.1 AU): does not mean planet is there Circularization: eccentricity may be small Gliese 581: previously known to have Neptune-mass planet
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Habitable Terrestrial Exoplanet • Search for terrestrial planets around M dwarfs → larger reflex motion • Smaller stellar mass • Habitable zone closer (<0.1 AU): does not mean planet is there • Circularization: eccentricity may be small • Gliese 581: previously known to have Neptune-mass planet • 2 new planets: one with no eccentricity • Deduced mean planetary temperature: 0–40 C (depends on reflectivity) AST 248, Spring 2007
Gliese 581 Parameters AST 248, Spring 2007
Search for Life in the Universe Chapters 12 (Part 2) Unidentified Flying Objects (UFOs) AST 248, Spring 2007
Outline • UFOs • Crashed Aliens in Roswell, NM • Crop Circles, Abductions, etc. • Ancient Visitations • Cover-Up & Scientific Disinterest AST 248, Spring 2007
UFOs • Appearance • Jet planes first introduced at the end of World War II public aware of fast-moving aircrafts • First UFO claim in June 1947 • “Flew erratic, like a saucer” flying saucer • ~50% of the public believe in the existence of UFOs • Air Force Investigation • 20-year investigation • 90% of claims discarded • Remaining 10% indeterminate • Lack of proof is no proof AST 248, Spring 2007
Crashed Aliens in Roswell, NM • Known facts • Rancher found crash remnants July 1947 • Military personnel picked up the debris • Remains shown next day in Fort Worth, TX • Claimed to be remains of a weather balloon • Claims by Stanton Friedman (1978) • Crash an alien spacecraft • Alien bodies also recovered • Story hushed up by military • Analysis • Project Mogul: balloon used for secret monitoring of Soviet tests • Witness accounts in seventies contradicted or discounted • Motive for secrecy not clear • Ability to keep secret highly doubtful AST 248, Spring 2007
Crop Circles, Abductions, etc. • Crop circles: • Claim: too accurate and too quick to be done by humans • Shown to be possible • Some admitted to be pranks • Abductions: • Sleep paralysis: common dream during rapid eye movement (REM) • Also known during day dreaming AST 248, Spring 2007
Ancient Visitations • Ancient drawings • Claim: pictures of aliens • Counterclaim: other possibilities abound • Nazca markings • Claim: needed unavailable knowledge • Counterclaim: did not need unavailable knowledge • Claim: could only be seen from space • Counterclaim: could be form of worship • Egyptian pyramids • Claim: Egyptians could not build the pyramids by themselves • Counterclaim: it was shown that the pyramids could be constructed with tools available then AST 248, Spring 2007
Cover-Up & Scientific Disinterest • Cover-up • Motive to avoid alarm: 50% already think that aliens have landed • U.S. Government notoriously unable to keep secrets known by many for a long time • All other governments need to participate in the conspiracy • Scientific disinterest • Stems from lack of evidence, not disinterest • If there was serious evidence, or the chance to obtain serious evidence, scientists would jump at it AST 248, Spring 2007