1. Welcome to Astronomy 210 Life in the Universe

2. “The Search for Life in the Universe” 3 rd Edition Goldsmith 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??

10. The Sizes and Numbers of Objects in the Universe

11. Solar System Inventory: 1 Star

13. Solar System Inventory: 9 Planets

14. The Terrestrial Planets

15. The Jovian Planets

16. Solar System Inventory: 91 + moons

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

19. Terrestrial Characteristics: Metallic core Oxygen dominated (silicates) Material% (by mass) Iron35 Oxygen30 Silicon15 Magnesium13 Nickel2.4 Sulfur1.9

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

22. Jovian Characteristics: Solid metallic-rocky cores Hydrogen dominated Material% (by mass) Hydrogen74 Helium24 Water0.6 Methane0.4 Ammonia0.1 Rock & Metals0.3

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

25. Pluto-Like?

26. 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

27. The Sizes of Stars in our Universe

30. The Distribution of Stars in the Universe

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

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

35. How many stars are in the Milky Way?

36. Orbital period sun ~ 240 million years Orbital distance sun ~ 28,000 light years M gal  100 billion M sun

37. 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

39. How are the galaxies distributed in the Universe?

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

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

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