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Astronomy 100: Exploring the Universe

Explore the cosmos in Astronomy 100. Learn fundamental concepts, stargazing, and more. Discover the mysteries of the universe in this thought-provoking course.

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Astronomy 100: Exploring the Universe

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  1. Astronomy 100Tuesday, Thursday 2:30 - 3:45 pmTom Burbinetburbine@mtholyoke.edu

  2. Course Material • Course Website:www.xanga.com/astronomy100 • Textbook:Stars, Galaxies, and Cosmology, The Cosmic Perspective, 3rd Edition by Bennett, Donahue, Schneider, and Voit • PRS: You need to have an InterWrite PRS transmitter.

  3. Goals of the Class for Me • The class should be interesting • You should learn some fundamental concepts in Astronomy • Motivate a few people to be Astronomy majors

  4. Course is divided into 4 Sections • The Night Sky • Gravity, Light, and Spacetime • The Nature of Stars • Galaxies and the Universe

  5. Star Trek • Antimatter • Faster than Light Travel • Alien Races

  6. Battlestar Galactica • Interstellar Travel

  7. Theme • Does life exist elsewhere in the solar system? • Does life exist elsewhere in the Universe?

  8. Grading • 4 in-class exams and a cumulative final • I will drop the lowest test score • The average of the 4 highest scores will be 80% of your grade • 10% of your grade will be your homework score • 10% of your grade will be from PRS

  9. Grades • 90-100 You get some type of A • 80-90 You get some type of B • 70-80 You get some type of C • 60-70 You get some type of D • If the average is not reasonable, I will curve up

  10. Exams • #1 Feb 15 Tuesday • #2 March 10 Thursday • # 3April 7 Thursday • #4 May 10 Tuesday • Final May 14-20

  11. Makeup Exams • If you miss an exam, I need a doctor’s excuse or documented family emergency to give a makeup exam • If you are going to miss an exam for a religious observance or university-sponsored activity, I need to be contacted in advance • I will be very strict since I am dropping one exam

  12. Homework • You need to get a maximum of 20 homework points out of ~30 possible points • If you get 20 points, you get 100% homework score • I will divide your homework score by 20 to calculate your percentage with a maximum total of 100% • Primarily the assignments will be on OWL

  13. 1st HW assignment • You need to find an article on astronomy (web, newspaper, magazine) • Print it, copy it, or cut it out • Read it • Write one paragraph on why it is important or why you found it interesting • Staple them together • Write your name and ID number on front page • Write the first three letters of your last name in big letters on front page • Hand it in during next class • You will then get 1 Homework credit!!

  14. PRS • 10% of your grade will be from using PRS • You need to get a maximum of 20 PRS points out of ~30 possible points • I will divide your PRS score by 20 to calculate your percentage with a maximum total of 100%

  15. Student Contract • I need you to turn it in by the 2nd class • If I do not get it, I will assume you have dropped the class

  16. If you are not enrolled in the class and want to be • Talk to me afterwards • I will try to get everybody in the class who wants to be in it

  17. Now some Astronomy • The first thing we will talk about is distance • The huge distances that occur in the universe

  18. Things you need to know because we will use the metric system • one kilometer is 5/8 of a mile • one kilometer is 1000 meters • one meter is approximately a yard or 3 feet • We will use the metric system in this class • Do you all remember the Mars Climate Orbiter?

  19. 5,900 million km = 5,900,000 million meters 590 meters The distances are one ten-billionth of their actual values

  20. So how far have we travelled? • What is the only planetary body that humans have walked on? • How many planets have spacecraft visited? • What spacecraft has travelled the farthest from Earth? • How far away is the closest star system?

  21. So how far have we travelled? • What is the only planetary body that humans have walked on? • Moon (385,000 km away) • How many planets have spacecraft visited? • All planets except Pluto • What spacecraft has travelled the farthest from Earth? • Voyager 1 (14 billion km away) • How far away is the closest star system? • ~40 trillion kilometers away (Alpha Centauri)

  22. Scientific Notation • 10000 = 104 • 100000000 = 108 • 10000000000 = 1010 • 100000000000000000000 = 1020 • 0.001 = 10-3 • 0.0000001 = 10-7

  23. How do you write numbers? • 31700000 = 3.17 x 107 • 2770000 = 2.77 x 106 • 0.00056 = 5.6 x 10-4 • 0.0000078 = 7.8 x 10-6

  24. How do you do multiply? • 106 x 108 = 10(6+8) = 1014 • 10-5 x 103 = 10(-5+3) = 10-2 • (3 x 104 ) x (4 x 105) = 12 x 10(4+5) = 12 x 109 = 1.2 x 1010

  25. How do you divide? • 108/106 = 10(8-6) = 102 • 10-6/10-4 = 10(-6-(-4)) = 10-2 • (3 x 108)/(4 x 103) = ¾ x 10(8-3) = 0.75 x 105 = 7.5 x 104

  26. Terms for large distances • In the Solar System • astronomical unit (AU) = distance between Earth and Sun (1.5 x 108 km) • Mercury is at 0.4 AU from the Sun • Jupiter is at 5.2 AU from the Sun

  27. Light Year • A light year is the distance light travels in a year • The speed of light is the fastest anything can travel in the universe • How far is a light year: (3 x 108 m/s) x (1 yr) x (365 days/yr) x (24 hr/day) x (60 min/hr) x (60 s/min) = 9.46 x 1015 m • Alpha Centauri is 4.4 light years away from Earth

  28. When we are looking at stars or galaxies • We are looking into the past

  29. Milky Way Galaxy • Milky Way is 100,000 light years in diameter • There are ~100 billion stars in the Milky Way

  30. Stars in the Universe • Say there are 100 billion galaxies • Each galaxy has 100 billion stars • So how many stars in the universe

  31. Answer • Number of stars in universe • = (100 x 109) x (100 x 109) = 10000 x 1018 = 1 x 1022 • This is about the same number of grains of sand in every beach in the world

  32. Time

  33. Spaceship Earth • We are travelling through the Universe • Velocity = distance/time

  34. Earth is rotating • The Earth is rotating counterclockwise looking down the north pole • This is why the Sun rises in the East

  35. We are rotating around the Sun

  36. Average relative velocities of nearby stars is 70,000 km/hr Stars near us are also moving

  37. Doppler Shift Long wavelength You are here Short wavelength We can measure how spectral features at known wavelengths Change wavelength positions and determine how fast a star or galaxy is moving away from us

  38. The sun is rotating around the galactic center at 800,000 km/hr Stars in the Milky Way are rotating

  39. The Universe is also expanding Galaxies (outside the Local Group) that are farther away from us appear to be moving faster

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