Instructions for registering and using Mastering Astronomy ( Course Calendar:

Transcription

1 My homepage: Click on AST 2004: Instructions for registering and using Mastering Astronomy ( Course Calendar: Homework Assignments and Due Dates Exam Dates PDF files of class presentations 1

2 Important Information Instructor: Dr. Caroline Simpson CP 217A Course Learning Assistants (LAs): Mayen Gonzalez George Shaeffer Required: (see the syllabus online) Text: Cosmic Perspective 6th ed. Access to MasteringAstronomy online system Lecture-Tutorials for Introductory Astronomy, 3rd edition (from bookstore); not used! 2

3 Not all information will be provided in lecture; that s what the text is for. In-class lecture-tutorials: bring workbook to class every day! work in groups (3 to a group, preferably) follow instructions keep your work: these are part of your study materials for exams! In-class quizzing to see how you are doing bring ABCD card to class every day! Participation grade How it works 10%, based on unannounced short-answer quizzes in class 3

4 My goals for the course: To help you develop: a basic understanding of the central ideas of astronomy an appreciation for the role astronomy has played in shaping the consciousness of the world in the past, at present, and what the future holds a real world perspective for how astronomy is connected to your daily lives (it is! Really!) the skill and motivation to pursue life-long learning and become a valuable member of the workforce and our society 4

5 Science is not... A list of previously known facts about nature A list of equations handed down from Ancient Times A set of laws discovered by Dead White Guys a long time ago and kept from the general public 5

6 Science is... a continuing process that seeks to understand the rules and laws of nature uses systematic observations uses mathematical models experimentally tests ideas subject to independent verification These are the components of the scientific method (observe, theorize, predict, test, and modify) used to comprehend the universe. 6

7 Reading Assignment Chapter 1 in Cosmic Perspective 7

8 What is our place in the universe? 8

9 Planet Orbits a star Massive enough to pull itself into a sphere shines by reflected (not emitted) light: doesn t produce energy via nuclear fusion as stars do large enough to have cleared the area of any other objects in/near its orbit 9

10 Moon (satellite) An object that orbits a planet Ganymede (orbits Jupiter) 2005 Pearson Education Inc., publishing as Addison-Wesley 10

11 A relatively small Asteroid and rocky object that orbits a star. 11

12 Comet An icy/rocky object that orbits a star 12

13 Comet

14 Solar (Star) System A star and all the material that orbits it, including planets, moons, asteroids, and comets 14

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16 Our Solar System Size scale is correct; distance scale is not! 16

17 The Sun has a diameter of approximately 1.4 million kilometers. Roughly how many Earths would fit across the diameter of the Sun? A.10 B.100 C.1,000 D.10,000 E.1 million 17

18 Size of the Sun Lecture Tutorial Work in your group Read the instructions and questions carefully Talk to each other and discuss your answers with each other Come to a consensus answer you all agree on if you get stuck or are not sure of your answer, ask another group If you are really stuck or don t understand what the Lecture Tutorial is asking, ask one of us for help 18

19 Did you get the key ideas from the Sun Size Lecture Tutorial? 19

20 Which statement do you think best represents the size comparison between the diameter of the Sun and the distance between the Moon and Earth? The Sun s diameter is A. Smaller than the distance between the Earth and the Moon B. Approximately equal to the distance between the Earth and the Moon C. Larger than the distance between the Earth and the Moon 20

21 If you were to construct a scale model of the solar system that used a 2 cm cherry to represent the Moon, how large of a ball would you need to represent the Sun? A. 4 cm B. 30 cm C. 110 cm D. 440 cm E. 880 cm 21

22 Our Solar System on a 1-to-10 billion (10 10 ) scale 2005 Pearson Education Inc., publishing as Addison-Wesley 22

23 Factor Name Prefix Symbol Number trillion Tera- T 1,000,000,000, billion Giga- G 1,000,000, million Mega- M 1,000, thousand kilo- k 1, hundred hecto- h ten deca- d one! hundredth centi- c 1/ thousandth milli- m 1/1, millionth micro- µ 1/1,000, billionth nano- n 1/1,000,000,000

24 The Astronomical Unit (A.U.) The A.U. is the average distance between the Earth and Sun = the size of the Earth s orbit (radius). 1 A.U. = 93 million miles 1 A.U. = 150 million km 1 A.U. =12,000 Earth Diameters = 110 Sun diameters 24

25 Object Size Scale Distance meters feet AU Sun grapefruit Mercury Venus Earth ballpoint Mars Jupiter marble Saturn Uranus Neptune Pluto dust speck

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27 poor_pluto_mathias_pedersen.jpg

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29 Star A large glowing ball of gas that generates energy (light, heat) through nuclear fusion 2005 Pearson Education Inc., publishing as Addison-Wesley 29

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31 Other stars in our galaxy

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34 Which of the following is not a general difference between a planet and a star? A. Planets orbit stars, while stars orbit the center of the galaxy. B. Planets are dimmer than stars. C. All planets are made of rock and all stars are made of gas. D. Planets are smaller than stars. 34

35 How far away are the stars? 35

36 Light-year The distance light travels in one year, moving at 300,000 km/s This is about 6 trillion miles (10 trillion km) A light-year is a unit of distance, like miles or km, not a unit of time! 36

37 Our Galaxy: The Milky Way Galaxy: A great island of stars in space, all held together by gravity and orbiting a common center

38 How big is the Milky Way? Have to reduce scale by another 10 billion to 1-to light-year = 1 mm Alpha Centauri = 4.4 mm from Sun Milky Way is 100 m across (football field) 38

39 Suppose you tried to count the more than 100 billion stars in our galaxy, at a rate of one per second How long would it take you? A. a few weeks B. a few months C. a few years D. a few thousand years 39

40 Local Group of Galaxies 2005 Pearson Education Inc., publishing as Addison-Wesley 40

41 Our Milky Way Galaxy

42 Our Milky Way Galaxy

43 Other Galaxies 2005 Pearson Education Inc., publishing as Addison-Wesley 43

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45 NGC 1300: Barred Spiral

46 M87: Giant Elliptical Galaxy

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49 A typical galaxy is a. A. nearby object orbiting a planet B. large, glowing ball of gas powered by nuclear energy C. relatively small, icy object orbiting a star D. system consisting of one or a few stars orbited by planets, moons, and smaller objects E. collection of a few hundred million to a trillion or more stars, bound together by gravity 49

50 Clusters of Galaxies 50

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52 How many stars are there? Milky Way: > 100 billion stars Would take > 3000 years to count them at 1 star/second Universe: > 100 billion galaxies Total number of stars: 100 x 10 9 x 100 x 10 9 = 10 ( ) = More stars than there are grains of (dry) sand on all the beaches of Earth... 52

53 The Universe is a big place, perhaps the biggest. Kilgore Trout 53

54 Universe The sum total of all matter and energy 54

55 Which of the following has your "cosmic address" in the correct order? A. You, Earth, Milky Way Galaxy, solar system, Local Group, Local Supercluster, universe. B. You, Earth, solar system, Local Group, Milky Way Galaxy, Local Supercluster, universe. C. You, Earth, solar system, Local Group, Local Supercluster, Milky Way Galaxy, universe. D. You, Earth, Local Group, Local Supercluster, solar system, Milky Way Galaxy, universe. E. You, Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe Pearson Education Inc., publishing as Addison-Wesley 55

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57 Where did all this come from, anyway? 2005 Pearson Education Inc., publishing as Addison-Wesley 57

58 Stars form in clouds of gas and dust (nebulae)...

59 Stars create new elements by thermonuclear fusion... 59

60 Stars die, returning their atoms and molecules to the galaxy...

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62 New stars and planets (and people!) form from the gas and dust... 62

63 Cosmic Recycling: We are star stuff 2005 Pearson Education Inc., publishing as Addison-Wesley 63

64 How can we know what the universe was like in the past? Light travels at a specific, finite speed through space: 300,000 km/s Destination Moon Sun Sirius Andromeda Galaxy Light travel time 1 second 8 minutes 8 years 2.5 million years Thus, we see objects as they were in the past: The farther away we look in distance, the further back we look in time 2005 Pearson Education Inc., publishing as Addison-Wesley 64

65 At great distances, we see objects as they were when the universe was much younger The universe is ~14 billion years old, so the observable universe is ~14 billion light-years across 2005 Pearson Education Inc., publishing as Addison-Wesley 65

66 How do our lifetimes compare to the age of the Universe? 2005 Pearson Education Inc., publishing as Addison-Wesley 66

67 New Year s Day:The Big Bang Milky Way forms Sun and planets form Oldest known life (singlecelled First multicellular organisms 67

68 Relative to the age of the universe, how old is our solar system? A. It is about one-third the age of the universe. B. It is about 1% as old as the universe. C. It is between about 5% and 10% as old as the universe. D. It is nearly the same age as the universe. 68

69 Hubble discovered that: All galaxies outside our Local Group are moving away from us. The more distant the galaxy, the faster it is racing away. Conclusion: We live in an expanding universe Pearson Education Inc., publishing as Addison-Wesley

70 Expansion of the Universe 70

71 What do we mean when we say that the universe is expanding? A. Everything in the universe is gradually growing in size. B. Average distances between galaxies are increasing with time. C. Within galaxies, average distances between star systems are increasing with time. D. The statement is not meant to be literal; rather, it means that our knowledge of the universe is growing. 71

72 Earth rotates on axis: > 1,000 km/hr Earth orbits Sun: > 100,000 km/hr Solar system moves among stars: ~ 70,000 km/hr Milky Way rotates: ~ 800,000 km/hr Milky Way moves in Local Group Universe expands 72