1ASTR 1040 ASTR 1040 AccelAccelIntro Astronomy 2: Intro Astronomy 2: Stars & GalaxiesStars & GalaxiesProf. Prof. JuriJuriToomreToomreTA: Nicholas NelsonTA: Nicholas NelsonLecture 2 Lecture 2 ThurThur13 Jan 201113 Jan 2011zeus.colorado.edu/astr1040zeus.colorado.edu/astr1040--toomretoomreReading (overlap with 1030)Reading (overlap with 1030)••Chap 3, secChap 3, sec3.43.4(Nature of Science)(Nature of Science)••ChapChap4, 4, review allreview all(Making Sense of Universe)(Making Sense of Universe)••Read ChapRead Chap55, carefully, carefully(Light and Matter)(Light and Matter)••Begin reading Begin reading Chap 6 (Telescopes)Chap 6 (Telescopes)for Tues classfor Tues class• What is differentwith ““Accelerated Intro Accelerated Intro AstroAstro”” ? Ability to get comfortable with physical estimatesphysical estimates: “mathematical insights”, “quantitative problems”, being able to sketch out the reasoningTopics for Today Topics for Today ••Nature of astronomy as a scienceNature of astronomy as a science••Four fundamental forces, and background to Four fundamental forces, and background to gravitation (discuss Newton)gravitation (discuss Newton)••Electromagnetism: Light as wavesElectromagnetism: Light as waves••Coupling of atoms and lightCoupling of atoms and light••Yields Yields ““spectral linesspectral lines””that are fingerprints that are fingerprints uniqueuniqueto each atomto each atomFOURFOURFUNDAMENTALFUNDAMENTALFORCESFORCESAt work everywhere,At work everywhere,““UniversalUniversal””We We assumeassumeand and testtestIsaac Newton and GravitationIsaac Newton and Gravitation(1642(1642--1727)1727)16871687232124/( )pa GMMNewton explainsNewton explainsKeplerKepler’’ssorbits:orbits:212()/gFGMM dNewtonNewton’’ssGravitationalGravitationalForceForceadmits admits these orbitsthese orbitsElliptical is Elliptical is the generalthe general““bound orbitbound orbit””2ELECTROELECTRO--MAGNETICMAGNETICRADIATIONRADIATION(used for most(used for mostdeductions)deductions)PHOTONSPHOTONS(quanta (quanta ––particles of light )particles of light )PROPERTIESPROPERTIESOF WAVESOF WAVESEE--M (LIGHT) M (LIGHT) AS WAVESAS WAVESSpeed of lightSpeed of lightSAMESAMEfor all for all wavelengthswavelengthsDiscuss SI units and Discuss SI units and ““how to get how to get comfortable with the speed of lightcomfortable with the speed of light””EE--M M SPECTRUMSPECTRUMQuantumQuantumMechanicsMechanics(energy of(energy ofphotons varies)photons varies)Electromagnetic SpectrumElectromagnetic Spectrumgammagamma--rays xrays x--rays ultraviolet rays ultraviolet visiblevisibleinfrared radioinfrared radio3ATOMSATOMSprotons,protons,neutrons,neutrons,electronselectrons(and quarks ..)(and quarks ..)Building blocksBuilding blocksfor everythingfor everythingNucleus and its electron cloud ....Nucleus and its electron cloud ....Atoms Involve Big Empty SpacesAtoms Involve Big Empty Spaces(or 1 Angstrom)(or 1 Angstrom)ORBITS OFORBITS OFELECTRONSELECTRONSPopping fromPopping fromone orbit toone orbit toanother involvesanother involvesparticularparticularPHOTONSPHOTONS(like DNA prints)(like DNA prints)ENERGY LEVELSENERGY LEVELS(of electrons)(of electrons)IN HYDROGENIN HYDROGENEach transitionEach transitioninvolves photonsinvolves photonsof specific colorof specific color(like fingerprints)(like fingerprints)UVUVVISIBLEVISIBLEIRIRHydrogenHydrogen’’ssEnergy DiagramEnergy