PowerPoint PresentationAST121 Introduction to AstronomyGetting to know you…SyllabusSlide 5Slide 6WebAssignMy Educational PhilosophyMy motivational speechChapter 1 - A Grand Tour of the HeavensWarm UpPsalm 19Measuring thingsPrefixesScientific NotationMassMass and WeightMasses of a few common objectsDistanceWhat about light?clight yearsecondSlide 24The nature of science“Doing” scienceExperimentCharacteristics of the Scientific Methoda few more comments...examples of modelsFor practiceThe Universe in 11 StepsStep 1 (20,000 km)Step 2 (2 x 106 km)Step 3 (1.2 AU, ~200 x 106 km)Step 4 (120 AU)Step 5 (12,000 AU = 0.19 light-years)Step 6 (20 light-years)Step 7 (2,000 light-years)Step 8 (200,000 light-years)Step 9 (20 million light-years)Step 10 (2 billion light years)Step 11 (greater than known universe)AST121 Introduction to AstronomyHigh Point UniversitySpring, 2004Dr. Aaron TitusGetting to know you…•Introduce yourself•The one-hand ice-breaker:–What is something you’re good at?–Where are you headed?–What is something that makes you angry?–Who do you love or what is something that you love?–What is something to remember you by?Syllabus•Course Description–An introduction to astronomy covering the motions, distances, and physical nature of heavenly bodies. Topics include the history of astronomy, the scientific method, and current views of cosmology.•Textbook–The Cosmos: Astronomy in the New Millenium by Pasachoff and Filippenko–This is required for the course and will be used extensively.–You should read the assigned chapter BEFORE class.Syllabus•Office: 342 HHSC•Email: [email protected]•Phone: 336-841-4668•Web: www.highpoint.edu/~atitus/•Class: M T Th 6:00 pm - 9:30 pm •Office hours–Before or after class is generally a good time to find me, but there are occasions when I’ll be unavailable.–Email is always a good way to reach me.Syllabus•Grading ScaleA+ (96), A (92), A- (88), B+ (84), B (80), B- (76), C+ (72), C (68), C- (64), D+ (60), D (56), D- (52), F (<52).•Grade Determination–experiments and in-class activities (25%), homework (20%), quizzes (15%), mid-term exam (20%), final exam (20%).•Homework–WebAssign (https://www.webassign.net/v4.html)WebAssign•Your username is your High Point username and your initial password is the same as your username.•Please log in tonight or tomorrow and email immediately if you have difficulty.•After logging in, go to “options” to change your email address (to the one you check most often) and your password.My Educational PhilosophyYou learn best when you are actively engaged with the subject through activities such as reading (and answering questions about what you read), discussing, experimenting, and solving problems. Lectures are useful for motivation, but for most students listening to lectures and copying lecture notes is an ineffective method to learn.My motivational speech•Focus on learning, not on grades. Learning brings success, and life-long learning brings life-long success.•If I offered to hire you for one month (30 days straight!) and offered to pay you $1,000,000 or 1 penny on the first day, but double your wages each day, which would you accept?•If you take the penny, you make over 5 million dollars on the 30th day (over 10 million for the month)•It’s how you grow that’s important, not how much you start with!Chapter 1 - A Grand Tour of the HeavensMeasurementsScientific NotationHow big is…?Scientific MethodWarm UpWhy should you learn about astronomy?Psalm 191 The heavens declare the glory of God;the skies proclaim the work of his hands.2 Day after day they pour forth speech;night after night they display knowledge.3 There is no speech or languagewhere their voice is not heard.4 Their voice goes out into all the earth,their words to the ends of the world.In the heavens he has pitched a tent for the sun,5 which is like a bridegroom coming forth from his pavilion,like a champion rejoicing to run his course.6 It rises at one end of the heavensand makes its circuit to the other;nothing is hidden from its heat.Measuring things•For us to communicate “how much” something is, we must use units.•What if I were to offer a job to you that pays an annual salary of 60,000 per year? Would you accept the job?•Three fundamental units used in the SI system (SI is the most common system of units used in science)–unit of mass, kilogram (kg)–unit of distance, meter (m)–unit of time, second (s)Prefixesprefix meaning power of 10micro one-millionth 10-61/1,000,000milli one-thousandth 10-31/1000centi one-hundredth 10-21/100kilo one thousand 1031000mega one million 1061,000,000giga one billion 1091,000,000,000tera one trillion 10121,000,000,000,000Scientific Notation•There is an easier way to express numbers so that we don’t have to count all those digits and commas.9850 kg = 9.85 x 103 kg = 9.85 x 106 g299,792, 458 m/s = 2.99792458 x 108 m/s384,403 km = 3.84403 x 106 km = 3.84403 x 109 m •The mass of the earth is 5.97 x 1024 kg. Do you really want to write that number without using scientific notation?Mass•a measure of inertia (how much net force is needed to accelerate an object)•independent of location in the universe•a measure of how much “stuff” an object is made of and what kind of “stuff” it’s made of; it depends on the atomic composition of which an object is madeMass and Weight•mass is NOT the same thing as weight!–near a large body such as a planet or moon or star, w = mg where g is the local acceleration due to gravity.–g depends on the mass of the large bodyBodyg (m/s2)weight(N) ofDr. Titusweight(lbs) ofDr. TitusEarth 9.8 800 180Moon 1.6 130 29Jupiter 25 2050 460Mars 3.7 300 67Pluto 0.1 8 1.8Masses of a few common objectsObject mass (kg)1 liter of water 1Earth 5.97 x 1024Moon 7.36 x 1022Sun 1.99 x 1030me 82universe ~1050hydrogen atom 1.67 x 10-27Distance•“how far” one point is from another point.•need to define the two points–distance of the center of the moon from the center of the earth–distance of the center of the moon from the center of the sun•need a standard–a meter, as defined by the length of a meterstick, is too arbitrary–a meter should be based on another unchanging and unarbitrary value.What about light?•Albert Einstein made a presupposition that the speed of light is the same in all reference frames (i.e. no matter how fast you are traveling and no matter what direction you’re