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A Census of the Solar System 1 star and 8 major planets Mercury Venus terrestrial giant Earth (1) Mars (2) Jupiter (39) Saturn (18) Uranus (23) Neptune (8) Planetary comparisons The Gas Giants Jupiter -- 1/1000 Msun , 300 Mearth 1/10 Rsun , 11 Rearth Terrestrial Objects 7 largest moons Other members Dwarf Planets – Pluto and the Trans-Neptunian or Kuiper Belt Objects Highly elliptical orbit inclined 170 to ecliptic Brings it inside Neptune’s orbit, 1979 – 1999, Pluto was closer than Neptune Asteroids, Meteors and Comets Fundamental Properties of the solar System 1. Planets and their satellites all lie in the same plane - the ecliptic – to within a few degrees 2. Sun’s rotational equator aligned with ecliptic 3. Planetary orbits are nearly circular ellipses 4. Planets all revolve in same W -> E direction 5. Sun and planets all rotate on axes in same W –E direction (except Venus and Uranus) 6. Distance between planets have a regular spacing (Bode’s Law) 7. Planet – satellite systems resemble solar systems 8. comets define a large almost spherical cloud surrounding the solar system – Oort Cloud 9. Planet compositions differ and there is a gradient with distance from the Sun 10. All mass is in the Sun (99.9%) but most of the angular momentum is in the planets Formation of Solar System The Condensation Sequence of the elements, minerals and molecules The Heavy Bombardment The Search for ExoSolar Planets Astrometric Detection Method Doppler Detection Method Transit Detection Method The first two methods are based on the fact that a planet orbiting a star will cause the star to "wobble" in space. The first method detects the component of this wobble that is horizontal to our line of site, and is based simply on observing the position of the star over time. ***The second method detects the component of the wobble that is radial to us, (i.e. directly towards or away from us), and is based on the Doppler shift in the star's light as the star moves towards or away from us. *** The third method is based on detecting the small drop in apparent luminosity of a star as a planet transits in front of it, between the star and the Earth. ExtraSolar System Planets Multiple systems As of Sept, 2015 -- 1892 planets confirmed (JPL) + 5596 candidates The Kepler Mission Designed to constantly survey the same region of sky 105 sg deg 1.4 meter diameter mirror with a 0.95m photometer. Uses the transit method and survey thousands of stars repeatedly at least 3 – 4 times to determine period and orbit of transiting planet. Results from Kepler satellite: Press release Feb 2, 2011 A NASA telescope taking a nose count of planets in one small neighborhood of the Milky Way registered more than 1,200 candidates, including 58 residing in life-friendly orbits around their parent stars. The census, collected by NASA's Kepler Space Telescope after just four months of work, shows that small planets like Earth are much more prevalent than Jupiter-sized worlds and that multiple-planet systems are common (about 200). As of Sept 2016 -- 2330 confirmed , + 4696 candidates Of these, 21 are in less than twice Earth size and in the habitable zone, http://kepler.nasa.gov/Mission/discoveries/ 11 new systems with 26 planets Kepler-22b: A 2.4 Earth-radius Planet in the Habitable Zone of a Sunlike Star Dec 5 , 2011 Probably about mass of Neptune ~ 35M earths Exo planet types First Earth-sized planet in the habitable zone of another star, April 2014 Finding Habitable Worlds Adaptive Optics – Interferometry – The Large Binocular Telescope Figure'2:'LEECH'observations'of'HR'8799'(left)'and'Kappa'And'(right).''These'are'the' most'sensitive'observations'taken'of'each'system.''No'planet'is'visible'interior'to'the' known'planets.' Characterizing% the% Atmospheres% of% Known% Exoplanets:% ESO Discovers Earth-Size Planet in Habitable Zone of Nearest Star The new planet circles Proxima Centauri, the smallest member of a triple star system known to science fiction fans everywhere as Alpha Centauri. Just over 4 lightyears away, Proxima is the closest star to Earth, besides our own sun. They determined that the new planet, dubbed Proxima b, is at least 1.3 times the mass of Earth. It orbits its star far more closely than Mercury orbits our sun, taking only 11 days to complete a single orbit -- a "year" on Proxima b. Web sites -- http://planetquest.jpl.nasa.gov/ exoplanet.eu exoplanets.org (Caltech) Kepler mission -- http://www.kepler.arc.nasa.gov/