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Welcome to A105 Stars and Galaxies

Welcome to A105 Stars and Galaxies. Instructor: Caty Pilachowski Assoc. Instructor: Tara Angle. Today’s APOD. Read units 1, 2, 3, 4.1 Essential Facts Worksheet due Thursday. Earth. Radius: 6400 km Distance from Sun: 150,000,000 km 1 AU, 8 light minutes. Radius: ¼ Earth’s radius

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Welcome to A105 Stars and Galaxies

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  1. Welcome to A105Stars and Galaxies Instructor: Caty Pilachowski Assoc. Instructor: Tara Angle Today’sAPOD • Read units 1, 2, 3, 4.1 • Essential Facts Worksheet due Thursday

  2. Earth Radius: 6400 km Distance from Sun: 150,000,000 km 1 AU, 8 light minutes Radius: ¼ Earth’s radius Distance from Earth: 384,000 km Moon

  3. TheSun Radius: 700,000 km Diameter: 1,400,000 km (about 100 x the diameter of Earth) Mass: 300,000 x mass of Earth

  4. Is Pluto a Planet? • What is a planet? • What must be considered to decide if Pluto is a planet?

  5. Pluto – Basic Data • Diameter: 0.18 Earth diameters • Mass 0.002 Earth masses • Inclination 17 degrees (other planets 7 degrees or less) • Eccentricity 0.25 (other planets less than 0.2)

  6. Guidance from the Discovery of Ceres • 1801 • Planet suspected between Mars and Jupiter • Campaign organized to search the sky • Ceres - the first (and largest) asteroid to be found • A planet…. or not? Image from Hubble

  7. Ceres: Not! • Too small • Many more asteroids found shortly thereafter • Tens of thousands known today Pallas Juno

  8. What defines a planet? • Round (enough mass for strong gravity) • Dominant body (tosses smaller bodies out of the Solar System) • Orbits the Sun

  9. First News Quiz • In Class QUIZ - Sept. 5 • Astronomy Magazine article on Pluto: www.astronomy.com/asy/default.aspx?c=a&id=4474 Use the “News Quiz” link on Oncourse to find the article

  10. Who’s in the class? • Freshmen? Sophomores? Juniors? Seniors? Other? • School…? • Major…?

  11. Science and the Distribution Requirement • Science and technology drive much of modern life • Jobs! • Informed voters make better decisions

  12. Why are you taking this class?

  13. Why are you taking this class? • I need to take a science class and astronomy sounded easy/fun • I've always been interested in astronomy • I had space in my schedule for another course and thought I'd try astronomy • I want to be a science teacher • I'm thinking of minoring/majoring in astronomy. • My friend is taking the class, so I'm taking it with her/him. • This is supposed to be an easy course, and I need to bring up my GPA • This course was recommended by a friend • I want to amaze my friends and family with my knowledge of the night sky.

  14. Where will we start? The night sky Learning to see with an astronomical eye Size and scale Where are we going? Modern Astrophysics A little physics Tools Understanding the Universe

  15. The Nearest Stars The closest star to our Sun is Proxima Centauri, about 4 light years distant.

  16. Most of the stars we see in the sky are within 250 light years

  17. Our Sector of the Galaxy The Sun lies along one of our Galaxy’s spiral arms, known as the Orion Arm

  18. View of theMilky Way Galaxy The Sun is about 26,000 light years from the center. Our Milky Way galaxy contains two hundred billion stars.

  19. Our Milky Way Galaxy is part of a small cluster of about 3 dozen galaxies.

  20. Virgo Supercluster Our Local Group of galaxies is part of a larger Supercluster of galaxy groups.

  21. Galaxies and clusters of galaxies collect into vast streams, sheets, and walls of galaxies.

  22. The Visible UniverseOn the largest scales, the universe seems to be more or less uniform

  23. Put these objects in the correct order from the nearest to the farthest from Earth • The Sun, the Milky Way, Alpha Centauri, Saturn, the Andromeda Galaxy • The Sun, Alpha Centauri, Saturn, the Andromeda Galaxy, the Milky Way • The Sun, Saturn, Alpha Centauri, the Milky Way, the Andromeda Galaxy • Saturn, the Sun, Alpha Centauri, the Milky Way, the Andromeda Galaxy

  24. Overview • Organization and course goals

  25. Office Hours Caty P.: Thursday, 11-noon SW 315 Tara Angle: Tues. 11-noon Weds. 2-3 PM SW 313 Course Organization • Syllabus/Oncourse • Text • Assigned Reading • Lecture Notes • Written Assignments • Projects • Quizzes • Observing

  26. GRADES • Quizzes (100 pts) • Homework Assignments (100 pts) • Observing Activities (100 pts) • Project (100 pts) • Exams (2 x 200 pts) • Final Exam (200 pts)

  27. Course Goals • Science as discovery • Use real astronomical data • Learn about the process of science Nova GK Per, known as the “Firework Nebula” exploded in 1901. The star lies 1500 light years away, in the direction of the constellation Perseus.

  28. One question I’ve always had about astronomy is…

  29. ASSIGNMENTSthis week • Read units 1, 2, 3, 4.1 • Essential Facts Worksheet due Thursday • 1st News Quiz next Tues.

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