1Birth of Modern AstronomyCelestial MotionLab starts this week—NS 017Bring lab manual to labDo Prelab 1 before you go!Peer Led Team Learning• Tuesday 5:45 to 7:45 PM• Library—Room 205• Add ES104X—CRN 12540• Can add before or during Oct. 8 session• Helps with vocabulary, concepts, confidence• Will have exam review sessions• Sit in to see if it is for youNicolausCopernicus• Earth rotates on an axis, instead of everything orbiting Earth• Earth orbits Sun like the planets, so it a planet too• “On the Revolution of the Heavenly Spheres”, 1543http://www.hao.ucar.edu/public/education/sp/images/copernicus.htmlTycho Brahe• Detailed observations of movement of planetshttp://www.hao.ucar.edu/public/education/sp/images/tycho.htmlTycho Brahe in his observatory• His careful observations and records are his most important legacyhttp://www.hao.ucar.edu/public/education/sp/images/tycho.3.htmlTycho’s 1572 Nova observationshttp://www.hao.ucar.edu/public/education/sp/images/tycho.1.htmlTycho’s comet of 1577http://www.hao.ucar.edu/public/education/sp/images/tycho.2.htmlTycho’smodel of solar system• Discounted Copernicus model because he could not discern stellar parallax• It does exist, he didn’t have tools to see ithttp://www.hao.ucar.edu/public/education/sp/images/tycho.4.htmlJohannes Kepler• Tycho’s assistant and successor• Used Tycho’s data to determine planetary orbits are ellipticalhttp://en.wikipedia.org/wiki/Image:Johannes_Kepler.jpg2First Law of Planetary Motion•Orbit of planet is ellipse• Sun at one FocusKepler’s 2ndLaw• Equal areas in equal time intervals accounts for the uneven speedsKepler’s third law of planetary motion•p2=d3p=Period (time to orbit Sun) in Earth yearsd=Distance in Astronomical Units: 1 A.U.=distance from Earth to SunGalileo Galilei• Strong supporter of Copernican model of planetary movement• Built 30x telescopes (from descriptions of the devices) and looked at planets and Moon starting in 1609http://en.wikipedia.org/wiki/Galileo_Galilei#TechnologyGalileo’s notes on Jupiter’s moons• Telescope used to see that another body in solar system is a center of orbital movement• These moons are not left behind, and Earth’s Moon is not eitherPtolemaic version of VenusPhases of VenusGalileo’s explanation of Venus’phasesMoon’s surface has texture3Galileo’s Astronomical Discoveries• When viewed by telescope, planets look like discs, not points of light as stars do• Jupiter has moons• Venus has phases• Moon’s surface has texture• Sun rotates on an axisFoucault’s Pendulum• 1851• Proved Earth does rotate on its axis—Copernicus’hypothesisIsaac Newton• Invented the calculus to simplify calculations• Explained the orbital motion of planets as the interaction of inertia and gravityOrbital motion of planets Brief Review• Sun is at the center of the solar system• Published by Copernicus– Supported by Galileo’s telescopic observations of Jupiter and Venus• Kepler determined orbits are ellipses• Newton determined orbits created by interaction of inertia and gravityConstellations• Star groups• 88 recognized• Stars names by brightness in themOrion• Southern Sky• Hunter•White Tiger• http://lithops.as.arizona.edu/~jill/EPO/Posters/Orion/protoplanets.htmlStar names in Orion• http://borghetto.astrofili.org/costellazioni/costellazioni.htmOrion’s place in the sky• Bright star to lower left of Orion is Sirius• http://www.windows.ucar.edu/the_universe/images/starmaps/map_orion.jpg4Sirius• “The Dog Star”• Brightest star in sky• In Canis Major• http://www.windows.ucar.edu/cgi-bin/tour_def/the_universe/images/starmaps/map_canis_major_jpg_image.htmlArcturus• Second brightest in northern sky•Very large• Rather cool• http://www.windows.ucar.edu/cgi-bin/tour_def/the_universe/Arcturus.html• http://en.wikipedia.org/wiki/ArcturusCelestial positionEarth turns pointed at Polaris Polaris and Big Dipper Polaris and Big DipperPolaris and Big DipperPolaris and Big Dipper—each 8 hoursWhat is a ‘day’?• Mean Solar Day5What is a ‘day’?• Sidereal Day• Incredibly distant stars—closest is 60,000+ times further than SunWhat is a ‘day’?• Mean Solar Day—24 hours• Sidereal Day—23 hours, 56 minutesPlane of the eclipticAnimation of equinox and solsticeEquinox and solstice related to the plane of the eclipticConstellations on the eclipticEarth Movement• Revolution (orbit) around Sun– Proposed by Copernicus: prediction that other planets would have phases like Moon– Galileo found phases of Venus with telescope observations• Rotation on axis– Tested with pendulum swing over a 24-hour day, by Foucault, in 1851• Precession of axial directionAxial wobble--precession• http://video.google.com/videoplay?docid=4242610371139275474&q=precession+of+equinox&total=54&start=10&num=10&so=0&type=search&plindex=4Phases of MoonAnimation link -- http://www.astro.virginia.edu/class/oconnell/astr121/im/lunation-anim.gif6Moon’s Motion• Takes 29 ½ days to proceed through its phases—Synodic month• Same side always faces Earth• Rotates on axis once each 27 1/3 days—Sidereal month• No atmosphere—extreme temperature variation: 127oto -173oCSidereal vs. Synodic Month• Sidereal with reference to a distant star• Note the directions of view are parallel• http://www.astro.virginia.edu/class/oconnell/astr130/im/moon_sidereal.gifLunar Eclipse• Moon is in Earth’s shadow during Lunar eclipseSolar Eclipse• Earth is in Moon’s shadow during Solar eclipseSolar Eclipse Eclipse geometry• Moon’s orbital plane around Earth at an angle to Earth’s orbital plane around Sun• Favorable for eclipse twice each yearMoon• 3475 km diameter• Density ~ Earth’s mantlehttp://www.astrosurf.com/cidadao/moon_99_03_01.jpgMeteor Impact Compression Wave7Ejecta Rim Euler Crater Lunar Features• Maria dark colored lowlands basalt• Terra pale colored highlands anorthositeMaria Formation• More craters indicated older surfaces•No weathering and erosion like on EarthFlood Basalt Lunar ExplorationFootprint in lunar regolithMoon formationhttp://www.psi.edu/hartmann/pic-cat/Impact of asteroidhttp://www.psi.edu/hartmann/pic-cat/8Ejecta from impacthttp://www.psi.edu/hartmann/pic-cat/Coalesced to form Moonhttp://www.psi.edu/hartmann/pic-cat/Moon was initially hothttp://www.psi.edu/hartmann/pic-cat/Moon by Apollo 17 CrewRight part of photo is
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