The Overview EffectCourse AnnouncementsAssignmentsPale Blue DotChapter 1What is AstronomyWhat is AstronomyWhat is AstronomyScientific NotationThe Metric SystemThe Metric SystemAstronomical SizesAstronomical TimeCarl Sagan’s Cosmic CalendarCarl Sagan’s Cosmic CalendarCarl Sagan’s Cosmic CalendarOur Place in SpaceOur Place in SpaceOur Place in SpaceThe Scale of the UniverseUnderstanding the Night SkyUnderstanding the Night SkyUnderstanding the Night SkyUnderstanding the Night SkyUnderstanding the Night SkyExamplesThe Overview EffectCredit:NASA/NOAAImages captured by the EPIC camera on NASA’s DISCOVR satelliteCourse Announcements•Astronomy Labs Start Next week•Register for Mastering Astronomy as soon as possible!Course ID: LINDSAYA151F16•Buy 3 x 5 Notecards for Notecard QuestionsAssignmentsReading Assignments•Chapter 1. Sections: 1.1, 1.3, 1.4[Read by Monday, 22 Aug.]Parallel Lectures•CC Astronomy Episodes 1 & 2[Watch by Monday, 22 Aug.]Mastering Astronomy•Introduction to Mastering Astronomy[Due Thursday, 25 Aug. at 11:59 PM EDT]Pale Blue DotCarl SaganVideo Link You Are HereCHAPTER 1 Charting the HeavensCredit: Dan & Cindy Duriscoe, FDSC, Lowell Obs., USNOWhat is Astronomy•Astronomy is the study of the Universe–Universe: the total of space, time, matter, and energy–Study of celestial objects (seen and unseen) and the physics that governs them.•Is not Astrology! [We don’t pseudoscience here]•Concerned with big picture questions:–Where did everything come from? Where is everything going?–How did the Universe/Solar System/Earth/life form?•Concerned with everything from the largest structures [Cosmic Microwave Background and the Cosmic Web] to the smallest structures [Modern Atomic Physics] in the UniverseIt’s a science!What is Astronomy•Astronomy is the study of the Universe–More precisely, the study of celestial objects and the physics that governs them.–Universe: the total of space, time, matter, and energyIt’s a science!Our laboratory is the universe.Our instruments are telescopesESO’s VLT ObservatoryWhat is Astronomy•More precisely still, it is the study of (the) planets, moons, comets, asteroids, stars, exoplanetary systems, what lies between the stars (the interstellar medium), nebulae, galaxies, luminous matter, dark matter, dark energy, the structure of the universe, the origins and fate of the universe, etc…•No single person or type of astronomer can study all of these topics. In order to do so, a plethora of scientific, engineering, and humanity fields are required:–E.g.: Physics, mathematics, chemistry, geology, biology, engineering, psychology, philosophy, education, the arts of all kinds to communicate and inspire…•In order to effectively talk about this in a universal way, we need to have a few standards...The entire Universe!?!? That’s a lot of ground space to coverScientific Notation•A concise way to express large and small numbers•[Decimal Notation] x [Power of Ten]•Examples a. 100 = 1.0 x 102b. 10,000,000,000,000,000,000,000 = 1.0 x 1022c. 149,600,000 = 1.496 x 108d. 0.01 = 1.0 x 10-2 *e. 0.00000000067 = 6.7 x 10-10Or how to easily write large and small numbersScientific Notation – See Appendix 1* 10-2 = 1/102 = 1/100The Metric SystemNeed of a Standard System•The metric system is a standardized system of measure based on the powers of ten.… 0.001, 0.01, 0.1, 1, 10, 100, 1000, ...… 10-3, 10-2, 10-1, 100, 101, 102, 103, …•Systéme Internationale (SI) d’unités – Our agreed standard metric system•SI is a combination of a prefix indicating what power of ten and a base unit of measure –Prefixes next slide–length [meters, m], time [seconds, s], force [Newtons, N], energy [Joules], pressure [Pascals], frequency (Hertz), etc.The Metric SystemPrefix + Unit of MeasureImportant Prefixes for this classPrefix [symbol]Largegiga [G] = 109 (Billion)mega [M] = 106 (Million)kilo [k] = 103 (Thousand)Smallcenti [c] = 1/100 = 0.01(Hundredth)milli [m] = 10-3 (Thousandth)micro [µ] = 10-6 (Millionth)nano [n] = 10-9 (Billionth)Astronomical SizesSometimes things are so large they need a new unitThe light-year (ly), or the distance light can travel in the time of one year.- Speed of light, c = 3.0 x 105 km/s- 1 year = (365.25 days) x (24 hr) x (60 min) x (60 s) = 3.156 x 107 seconds- So, 1 ly = (3.0 x 105 km/s) x (3.156 x 107 s) = 9.46 x 1012 km- or 9,460,000,000,000 km; 9.46 trillion kilometersThe Astronomical Unit (AU) is the average distance between the Earth and the Sun.- 1 AU = 1.496 x 108 km (1.5 x 108 km is close enough)- Ex. Jupiter is 5.2 AU from the Sun instead of 7.8 x 108 km.Astronomical Time•Age of the Universe: 13.798 ± 0.037 billion years (ref)–As determined by NASA’s Planck Mission–13.798 Gyr•Age of the Solar System: 4.5682 billion years (ref)–As determined by Lead-Lead (Pb-Pb) dating of meteorites–4.5682 Gyr•Age of Modern Humans (Homo Homo Sapiens)–Approximately 200,000 years –0.001% age of Universe; 0.004% age of SSThe age of thingsCarl Sagan’s Cosmic Calendar•Imagine scaling the entire history of the Universe (13.8 Gya) to fit on a calendar.•January 1st the instant past midnight is the Big Bang, or start of the Universe (in time as we understand it)•The present moment is at December 31st at the instant before midnightMonth: 1.14 Gya Day: 37.5 MyrHour: 1.6 Myr Min: 26,000 years Sec: 435 years The age of things in perspectiveCarl Sagan’s Cosmic CalendarCosmic Calendar’s December15 December: First Animals25 December: Dinosaurs30 December: Dinosaurs go extinct31 December after 11:54 PM -> Age of Modern HumansCarl Sagan’s Cosmic CalendarCosmic Calendar’s Final MinuteOur Place in SpaceOur cosmic address: Earth, Solar System, Milky Way Galaxy, The Local Group, Laniakea Supercluster, the UniverseUNIVERSELocal Supercluster – 100,000,000 lyLocal Group 10,000,000 lyMilky Way 1,000,000,000,000,000,000 kmOr - 100,000 light yearsSolar System10,000,000,000Earth – 12,800 kmOur Place in SpaceUNIVERSELocal Supercluster – 108 ly or 100 MlyLocal Group 107 ly or 10 MlyMilky Way – 1018 kmOr - 105 light yearsSolar System – 1010 kmEarth – 12,800 kmOur cosmic address: Earth, Solar System, Milky Way Galaxy, The Local Group, Laniakea Supercluster, the UniverseOur Place in SpaceA bit more precisely. These are all structures we will study in this course. You should have and idea of which is bigger than which.The Scale of the
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