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Homework Update

Homework Update. Complete Homework sections at the end of the Notes for the first lecture (Tuesday) and today’s lecture (Thursday) on calendar section of mctcteach.org/astronomy Homework Highlights Email me by 9am on 30 August 2014 (instructions in notes)

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Homework Update

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  1. Homework Update • Complete Homework sections at the end of the Notes for the first lecture (Tuesday) and today’s lecture (Thursday) on calendar section of mctcteach.org/astronomy • Homework Highlights • Email me by 9am on 30 August 2014 (instructions in notes) • Complete the first D2L extra credit quiz • Make 2 flashcards/notecards to bring on Tuesday (write something on these notecards from the OBJECTIVES from last lecture or today) – not graded but used for attendance

  2. General Goals • Envision the size of the Earth-Moon system and the Solar System. • Work with large numbers (scientific notation). • Work with the metric system. • Design scale models.

  3. Attempts to “comprehend” the size of the Universe 1. Take virtual trips 2. Use big numbers like 4.2 X 1012 3. Use large units like a light year 4. Use scale models

  4. 1. Virtual Trips Travel the universe - saw last time http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/index.html More Videos – See my notes Web http://apod.nasa.gov/apod/ap100120.html

  5. Ranking Exercise • 1. Complete ranking exercise on your own. <TWO MINUTES> • 2. Find two partners. Introduce yourself. Agree on the rankings. Pick up another sheet for your group. Fill it in and hand it in (PRINT FIRST AND LAST NAMES). <FIVE MINUTES>

  6. Ranking Exercise • Rank the following objects from smallest (1) to largest (5): 4 Solar System 2 Earth 1 Our Moon 5 Milky Way galaxy 3 Average star like our Sun

  7. Ranking Exercise • Rank the following distances from Earth (1=closest,…, 6=most distant): 5 Center of Milky Way Galaxy (~27 000 ly) 2 Our Sun 1 Moon 4 Next nearest star (after Sun) (~ 4 ly) 6 Andromeda Galaxy (nearest neighbor galaxy to ours) (2.5 x 106ly) 3 Pluto

  8. 103 means 10 X 10 X 10 = 1000 2. Large (or small) numbers Brief review of powers of ten:

  9. 108 is 100 000 000 (Use spaces not commas) 10-8 is 0.000 000 01 (Use a 0 in front of the decimal) Practice problems are available in the notes. http://www.mctcteach.org/astronomy Brief review of powers of ten:

  10. 6.3 X 102 means 6.3 X 100 which is 630 Scientific notation (handout) Review Scientific Notation

  11. 6.3 X 102 For a short cut, start with 6.3 Then move the decimal two places right giving 630 Scientific notation (handout) Review Scientific Notation

  12. 2.81 X 104 Start with 2.81 Move the decimal four places right. 28 100 Review Scientific Notation

  13. 8.2 X 10-5 Start with 8.2 Move the decimal five places to the left. 0.000 082 Practice problems with answers are in the notes on the class website. Review Scientific Notation

  14. 3. Units • Any standard of measurement or exchange • Ex. In 3 feet, the units are feet • Ex. In 5.5 s, ? • Ex. In $6, ?

  15. SI System of Units • In science, use the SI system (meter, kilogram, second)

  16. Identify m, cm, mm • Common Objects

  17. Examples • Given some lengths, find a common object that is that size. • 1 mm - 1 m • 1 cm - 2 m • 10 cm - 4 m • 30 cm - 10 m • 1 m ~ 1 giant step, 1 cm ~ thickness of pencil, 1 mm ~ thickness of paper clip wire

  18. Unit Prefixes • centi, milli • nano, micro, milli, centi, kilo, mega, giga

  19. Astronomical Unit Larger, commonly used unit Abbreviation – AU Meaning – Average Earth-Sun distance (1 AU = 150 000 000 km = 93 000 000 mi) Ex. How far from Earth to Sun? Ex. How far from Sun to Pluto? Ex. How far to edge of our solar system?

  20. Light year Larger, commonly used unit Speed of light = 186 000 mi/s = 300 000 km/s = FAST = 7 ½ times around Earth in one second!!

  21. **Light-year (symbol ly) Distance light travels in one year** 1 ly = 1 x 1016m Example – Sun to Proxima Centauri ~ 4.2 ly Light from the Sun takes ~4.2 years to reach the NEXT nearest star (~20 000 years by rocket) Note: Textbook Appendix A The Nearest Stars uses pc = parsec = 3.26 ly (don’t need to use pc in this class) http://apod.nasa.gov/apod/ap051204.html

  22. Light-year (ly) Andromeda Galaxy (right) ~ 2.5 Mly Milky Way Galaxy diameter ~100 000 ly (thickness=1000 ly)

  23. Light-year (ly) Distant Galaxies ~ 10 billion ly (Bly) Most distant galaxies ~ 13 giga ly (Gly)

  24. 4. Scale Models • Help picture things so you can think about them. • Can be larger or smaller. • Examples: 1. Architecture: structures, landscapes 2. Toys: Rockets, Dolls 3. Science: Atom, Earth globe

  25. Scale Model of U.S. • Scale the U.S. to a scale of 1 mm = 10 mi (equivalently 1 cm = 100 mi and 1 m = 10 000 mi) • Given data Twin Cities’ diameter is ~20 mi Chicago’s diameter is ~50 mi TC to Chicago is ~600 mi TC to NYC is ~1000 mi TC to LA is ~2000 mi TC to Moon is ~240 000 mi

  26. Scale Model of U.S. • Question: It is about 1 mi to the downtown library from here. If you wanted to represent that distance on your scaled map, would you use a pencil point dot or the diameter of a dime to represent that distance? Explain.

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