1ASTR 113Lecture 1withProfessor Dr. Harold GellerIntroduction• Syllabus– Online; printed copy available the first lecture only, in class• Grading– Summarizing (see webpage): 33.3% each in-class exam and final (final is comprehensive)• ALL Exams – calculators, pencils, scantron (bring your own)and ID only – follow posted rules or “F”– NO MAKE-UP EXAMINATIONS• I repeat NO MAKE-UP EXAMINATIONS– Extra credit using iClickers; NO SUBSTITUTIONS• Repeat: ONLY extra credit is via the iClickers useageIntroduction• Textbook–Universe (7thedition) by Freedman and Kaufmann• Optional Auxiliary Materials–Personal Response System•iClickerIntroduction (continued)• Web notes– Will be updated routinely; check back often• Observing Sessions at Rooftop Observatory– Offered on campus for your learning experience and enjoyment• F&K Chapters 4 & 5 Review– Basic ideas reviewed in this lecture• Read textbook and think about what is being saidKepler’s Laws of Planetary Motion• Kepler’s First Law of Planetary Motion– planets orbit sun in an ellipse with sun at one foci• Kepler’s Second Law of Planetary Motion– planets sweep out equal areas in equal times• travel faster when closer, slower when farther• Kepler’s Third Law of Planetary Motion– orbital period squared is proportional to semi-major axis cubed–P2= a3Newton’s Laws of Motion and Gravity• Newton’s First Law of Motion– body at rest tends to stay at rest and body in uniform motion will stay in straight line uniform motion unless acted upon by an outside force• Newton’s Second Law of Motion– the acceleration of a body is proportional to the force being applied–F = m a2Newton’s Laws of Motion and Gravity• Newton’s Third Law of Motion– for every force there is an equal and opposite force (action and reaction)• Newton’s Law of Gravitational Attraction– force is proportional to masses and inversely proportional to the distance squared»F = (G m M) / r2Wien’s Law• Peak wavelength is inversely proportional to the temperature of the blackbodyIntensityFrequencyCooler BodyHotter BodyPeak WavelengthStefan-Boltzmann Law• Energy radiated by blackbody is proportional to the temperature to the 4th power–E = σ T4Ener gy vs. Temperature01000020000300004000050000600000 2 4 6 8 10 12 14 16TemperatureEnergyKirchoff’s Spectral Laws• Kirchoff’s Spectral Laws (empirical)– Continuous Spectrum• what produces them?– Emission Spectrum• what produces them?– Absorption Spectrum• what produces them?Kirchoff’s First Spectral Law• Any hot body produces a continuous spectrum– if it’s hot enough it looks something like this– digitally like thisWavelengthIntensityKirchoff’s SecondSpectral Law• Any gas to which energy is applied, either as heat or a high voltage, will produce an emission line spectrum like this– or digitally like thisWavelengthIntensity3Kirchoff’s ThirdSpectral Law• Any gas placed between a continuous spectrum source and the observer will produce a absorption line spectrum like this– or digitally like thisWavelengthIntensityThe Photoelectric Effect• A prelude to the Bohr atom– experiment explained by Einstein, but performed by others• what caused this strange result?Prelude to Bohr• Einstein used Planck’s quantized particles–energy of photon is related to frequency of light, not intensity• need high enough frequency to get electrons released from metallic surface–E = h fBohr’s Atom• Best described the workings of the Hydrogen atom– one proton and one electron “around” the proton moving in orbits that are discretized (quantized) so that no intermediate orbits are allowedAbsorption EmissionMaxwell’s Electromagnetism• Electricity according to Gauss– relates electricity to electric charge• Faraday’s Law– relates electric fields to magnetic fields• Magnetism according to Gauss– relates magnetism to electricity• Ampere-Maxwell Law– relates magnetic field to electricityDon’t worry about notation hereDoppler Effect• A change in measured frequency caused by the motion of the observer or the source– classical example of pitch of train coming towards you and moving away4Conclusion• To understand the stars (and our Sun is a star), galaxies, and the universe at large (cosmology) you need to understand–Physics• Forces (gravity, electromagnetic, strong, weak)• Matter (protons, electrons, quarks, bosons, etc.)• Theories, Laws and Effects– Newton’s, Kepler’s, Kirchoff’s, Stefan-Boltzmann, Doppler, Photoelectric, Relativity, etc.–Chemistry• Atoms, elements, molecules and their models (e.g. Bohr)– And for Chapter 30, even a little