1. Charles Hakes Fort Lewis College1

2. Charles Hakes Fort Lewis College2 Prologue Seasons/Theories

3. Charles Hakes Fort Lewis College3 Outline Outside Lab Notes RA/Dec 0.2 Earth’s Orbital Motion. Day to day changes Seasonal changes Long term changes Scientific Theories SETI at home. Homework Due Wednesday

4. Charles Hakes Fort Lewis College4 Lab Notes Resources Part 2 in class this week. Noontime Sun for Friday Box outside Berndt 671. Sunset, Part1 for next Monday Note link to http://www.printfreegraphpaper.com/ http://www.printfreegraphpaper.com/ Box outside Berndt 671. Binocular Lab Thursday, Monday(?). Sign up…

5. Charles Hakes Fort Lewis College5 Homework Notes In Mastering Astronomy - make sure your ID is the same as your FLC ID.

6. Charles Hakes Fort Lewis College6 Your Folder Cut open “closed” folders. Full name on the tab BIG name on the front Major on upper right Class on lower left A comment about yourself on the lower right Inside - your most recent, or current, math class (subject, course number, and year taken.) Include your daily three minute papers! You can reuse pages, just add the date.

7. Charles Hakes Fort Lewis College7 Three Minute Papers Remove all spiral notebook fringe! Re-use pages - save trees Include date Say something SPECIFIC. Don’t say “I learned ABOUT…” unless you say what about it you learned. Instead, say “I learned THAT…” Bad: I learned about the velocity equation Good: I learned that v = x/t

8. Charles Hakes Fort Lewis College8 Introduction The Celestial Sphere

9. Charles Hakes Fort Lewis College9 Oslo, Norway is 60°N latitude. How high does the star Polaris appear? A) 0° B) 30° N C) 60° N D) 90° N

10. Charles Hakes Fort Lewis College10 What is the southernmost declination line visible from Oslo (at 60° N)? A) 60° N B) 30° N C) 0° D) 30° S

11. Charles Hakes Fort Lewis College11 What is the southernmost declination line visible from Oslo (at 60° N)? A) 60° N B) 30° N C) 0° D) 30° S

12. Charles Hakes Fort Lewis College12 Scale on Meridian Declination at zenith (overhead) is your latitude The celestial equator (0° dec) is to the south of your zenith by latitude amount. The celestial pole (90° dec) is your latitude amount above the north horizon. http://wps.aw.com/aw_chaisson_bg_6_mx/120/30970/7928552.cw/index.html

13. Charles Hakes Fort Lewis College13 Right Ascension Right Ascension corresponds to longitude. Units are Hours (and minutes and seconds). The trick (as with longitude) is to decide on the zero point. Longitude zero is at the observatory in Greenwich England. RA zero is where the sun crosses the celestial equator going north. RA is always moving w.r.t. longitude.

14. Charles Hakes Fort Lewis College14 Figure P.3 The Northern Sky

15. Charles Hakes Fort Lewis College15 How long is the exposure? Enter the correct number of hours. A) 4 B) 5 C) 6 D) 7 E) 8

16. Charles Hakes Fort Lewis College16 Earth’s Orbital Motion Day to day changes Seasonal changes Long term changes

17. Charles Hakes Fort Lewis College17 Day to Day Changes Solar Day Time from one noon to the next 24hrs Sidereal Day Time that a star passes directly overhead until it does so again. Less than 24 hrs.

18. Charles Hakes Fort Lewis College18 Figure P.5 Solar and Sidereal Days

19. Charles Hakes Fort Lewis College19 Solar vs. Sidereal day Edmund Scientific Star and Planet Finder The view of the night sky changes during the year.

20. Charles Hakes Fort Lewis College20 Figure P.6 The Zodiac

21. Charles Hakes Fort Lewis College21 Seasonal changes One sentence - why we have seasons.

22. Charles Hakes Fort Lewis College22 Seasonal changes What about seasonal changes in temperature? Let's propose a (wrong) theory: “the Earth is closer to the Sun in summer” What testable predictions can we make? (E.g., what is life like on the equator? Durango? Alaska? the North Pole? the southern hemisphere?) Any successful theory will make correct predictions regarding length of day and temperature, which together define the seasons.

23. Charles Hakes Fort Lewis College23 Theory: “the Earth is closer to the Sun in summer” Where on Earth would it be warmer at perihelion (closest approach to the Sun)? A) Northern Hemisphere B) Southern hemisphere C) Everywhere at the same time.

24. Charles Hakes Fort Lewis College24 Seasonal changes Where on Earth would it be warmer at perihelion in January? The answer is everywhere, unlike the reality of our world's seasons which vary by hemisphere.

25. Charles Hakes Fort Lewis College25 Seasonal changes Where on Earth would it be warmer at perihelion in January? The answer is everywhere, unlike the reality of our world's seasons which vary by hemisphere. This is a huge piece of knowledge, which most Americans get wrong! I absolutely insist that you all do better.

26. Charles Hakes Fort Lewis College26 Seasonal changes

27. Charles Hakes Fort Lewis College27 Seasonal changes Let's look at a different view. The left frame shows our initial theory, with no tilt. The right frame adds a tilt to the Earth's rotation axis.

28. Charles Hakes Fort Lewis College28 Figure P.8 Seasons

29. Charles Hakes Fort Lewis College29 Seasonal changes When the sun is high, the light rays are more concentrated - the sun feels hotter. When “your” hemisphere is pointed towards the sun, it receives more daylight hours compared to nighttime hours.

30. Charles Hakes Fort Lewis College30 Seasonal changes From the point of view of the Earth, the path of the Sun in the sky appears tilted compared to Earth’s equator. Ecliptic - The apparent path of the sun on the celestial sphere during the year. Equinoxes - Two points where the ecliptic crosses the celestial equator. Vernal equinox (first day of Spring ~Mar. 21) Autumnal equinox (first day of fall ~Sept 21)

31. Charles Hakes Fort Lewis College31 Figure P.7 Ecliptic

32. Charles Hakes Fort Lewis College32 Scale on Meridian Declination at zenith (overhead) is your latitude The celestial equator (0° dec) is to the south of your zenith by latitude amount. The celestial pole (90° dec) is your latitude amount above the north horizon. http://wps.aw.com/aw_chaisson_bg_6_mx/120/30970/7928552.cw/index.html Lab note - at the equinoxes, the sun is ON the celestial equator. At the solstices, the sun is north (or south) of the equator by 23.5° (the Earth’s tilt).

33. Charles Hakes Fort Lewis College33 Long Term Changes The Earth’s tilt wobbles Precession takes ~26,000 years.

34. Charles Hakes Fort Lewis College34 Figure P.9 Precession

35. Charles Hakes Fort Lewis College35 Introduction Scientific Theory

36. Charles Hakes Fort Lewis College36 Scientific Theory Theory - the framework of ideas and assumptions used to explain some set of observations and make predictions about the real world. Can prove them wrong by a single bad prediction. Can’t ever prove them “right.” They just get more widely accepted. Eventually, some theories might be called “law,” (e.g. gravity) but they are still just scientific “theories.”

37. Charles Hakes Fort Lewis College37 Scientific Theory Must be testable. Must continuously be tested. They should be simple. Occam’s Razor - if two competing theories both explain the facts, then the simpler one is better. KISS engineering - “Keep It Simple, Stupid.” They should be elegant.

38. Charles Hakes Fort Lewis College38 Discovery 1-1a The Scientific Method

39. Charles Hakes Fort Lewis College39 Is it possible to prove or disprove a scientific theory? A) Yes prove, yes disprove B) Yes prove, no disprove C) No prove, yes disprove D) No prove, no disprove

40. Charles Hakes Fort Lewis College40 SETI@home

41. Charles Hakes Fort Lewis College41 Chapter 18 Is There Intelligent Life Elsewhere in the Universe?

42. Charles Hakes Fort Lewis College42 Are we alone in the Milky Way? A) definitely B) probably C) maybe D) probably not E) no way

43. Charles Hakes Fort Lewis College43 The Drake Equation In science, the complete lack of any useful data does not always stop us. Instead, we proceed anyway, with a specialized equation to characterize our ignorance! The number of advanced civilizations in our Galaxy with whom we can communicate is: N = R f p n p f l f i f t L

44. Charles Hakes Fort Lewis College44 Figure 18.7 Drake Equation

45. Charles Hakes Fort Lewis College45 The Drake Equation R is the average rate of star formation (~10 stars/year) f p is the fraction of stars with planets (current evidence - nearly 1; that is, ~100% of stars form with planets) n p is the habitable planets per star with planets (the Chaisson textbook estimates 0.1) f l is the fraction of those planets with life (?!?) f i is the fraction of those life-bearing planets with at least one intelligent species (?!?) f t is the fraction of planets with an intelligent species in which that species develops technology capable of interstellar radio communication (?!?) L is the average lifetime of a technological civilization (our society has been capable of radio communication for only about 100 years; how much longer will we remain so? Are we a good model for other possible civilizations?)

46. Charles Hakes Fort Lewis College46 The Drake Equation Make your own estimate for the unknown values and calculate and answer for the Drake equation.

47. Charles Hakes Fort Lewis College47 How many technological civilizations are there in the Milky Way? (N = R f p n p f l f i f t L) A) 0 B) 1-9 C) 10-99 D) 10 2 -10 4 E) more than 10 4.

48. Charles Hakes Fort Lewis College48 The Drake Equation Suppose all the f terms that aren't specified above are nearly 1 (or 100%). (optimistic!) If we do that, then the lifetime of a civilization (in years) roughly equals the number of societies in our Galaxy. So if a technological society lasts for 100 years say, there would be 100 of them in our Galaxy. However, even if there are 100 other civilizations capable of radio communication in our Galaxy, and even if they're interested in talking to us, the average distance between civilized worlds is about 10,000 light years - so it would take 20,000 years to get a response to any message we send. Even if we suppose that there are 1 million civilizations out there, they'd still be separated by about 300 light years!

49. Charles Hakes Fort Lewis College49 The Drake Equation Go look for ET on your own! Run SETI@home on your computer, see: http://faculty.fortlewis.edu/hakes_c/ http://faculty.fortlewis.edu/hakes_c/ SETI@home is a scientific experiment that uses Internet- connected computers in the Search for Extraterrestrial Intelligence (SETI). You can participate by running a free program that downloads and analyzes radio telescope data.

50. Charles Hakes Fort Lewis College50 Scale of the Universe

51. Charles Hakes Fort Lewis College51 Powers of Ten http://www.wordwizz.com/pwrsof10.htm

52. Charles Hakes Fort Lewis College52 Three Minute Paper Write 1-3 sentences. What was the most important thing you learned today? What questions do you still have about today’s topics?