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Welcome to Astronomy 210

Join Astronomy 210 to delve into the fascinating topic of life beyond Earth. Learn about the sizes and numbers of objects in the universe, the solar system inventory, characteristics of terrestrial and jovian planets, cosmic distances, the distribution of stars, and the age of the universe.

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Welcome to Astronomy 210

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  1. Welcome toAstronomy 210 Life in the Universe

  2. “The Search for Life in the Universe” 3rd EditionGoldsmith and Owen

  3. Astronomy 210 Website is up • Pickup Powerpoint notes at the beginning of class • Powerpoint presentations online • Possible field trip to MLO • Frequent Astronomy 100 refreshers • Reading list soon…

  4. What should a “Life in the Universe” class cover??

  5. The Sizes and Numbers of Objects in the Universe

  6. Solar System Inventory: 1 Star

  7. Solar System Inventory:9 Planets

  8. The Terrestrial Planets

  9. The Jovian Planets

  10. Solar System Inventory:91 + moons

  11. Solar System Inventory:Countless numbers of Asteroids, Comets, Meteors, Dust

  12. Terrestrial Characteristics: • Metallic core • Oxygen dominated (silicates) Material % (by mass) Iron 35 Oxygen 30 Silicon 15 Magnesium 13 Nickel 2.4 Sulfur 1.9

  13. Terrestrial Characteristics: • Thin (or nonexistent) atmospheres • Few (or no) natural satellites • Closely spaced orbits

  14. Jovian Characteristics: • Solid metallic-rocky cores • Hydrogen dominated Material % (by mass) Hydrogen 74 Helium 24 Water 0.6 Methane 0.4 Ammonia 0.1 Rock & Metals 0.3

  15. Jovian Characteristics: • Thick gaseous atmospheres • Many natural satellites • Widely spaced orbits

  16. Pluto-Like?

  17. Cosmic Distances Astronomical units of distance: Astronomical Unit: The distance between the Sun and the Earth 93 million miles Light year: The distance light travels in a year Speed of light: 186,282 miles/sec Light year: 5.9 trillion miles

  18. The Sizes of Stars in our Universe

  19. The Distribution of Stars in the Universe

  20. How do we know how many stars there are in the Universe?

  21. If we literally counted the stars in each galaxy… 1 per second, 8 hours every day… 38,000 years!

  22. How many stars are in the Milky Way?

  23. How many stars are in the Milky Way? Orbital periodsun ~ 240 million years Orbital distancesun ~ 28,000 light years Mgal 100 billion Msun

  24. Does this represent the actual number of stars in our galaxy? • Our Sun is an “average star” in mass and luminosity. • The galaxy has many more low mass stars compared to high mass stars Adjusted estimate of stars in Milky Way: 300 – 400 billion stars

  25. How are the galaxies distributed in the Universe?

  26. How do we know how OLD the Universe is? Edwin Hubble - 1929

  27. It all depends on HO HO – The “Hubble Constant” • It is a measure of the slope of the line in the Hubble Diagram • Represents the expansion rate of the Universe

  28. Current observations suggest: Age of Universe ~ 14 billion years

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