1. Astronomy 1010 Planetary Astronomy Fall_2015 Day-9

3. Course Announcements SW chapter -2 due: Mon. 9/21; 2pm How is the lunar observing going? 1 st Quarter night – Mon. 9/21 -7:30pm – on campus Exam 1: Mon. Sept. 21 This Week: APSU-OUR: Research & Creative Activity Week. Events in the library 2:30-3:30 every day.APSU-OUR

4. Useful Information for Next Lab Motions of the Sun ClassAction Web Site (Link from apsu.edu/astronomy) Print the instructions BEFORE you come to class!

5. That Picture Question 37: <= 12hrs 14: 24 hrs 5: 10 hrs 4: 6 hrs 3: 14-16 hrs 2: “A night” 2: Answer had nothing to do with question 1: 5hr, 9.5hr, 8hr, 72 hrs,6 min, “Couple of days”, No Answer

6. i_Clicker Question ClassAction: Questions: Basic Motion: Seasonal Analogy

7. Stuff in Chapter 2 Coordinates Position Daily Motion (spin of Earth on its axis) Visibility of the sky Year Motion (Earth orbits the Sun) Seasons (tilt of the Earth’s axis) Precession of the equinoxes Motion and phases of the Moon Eclipses

8. Earth’s Axis  Earth’s axis is not perpendicular to the ecliptic plane.  Instead, it is at an angle of 23.5 degrees.  This is why there are seasons.

9. Earth’s Axis  The angle of sunlight is closer to perpendicular in summer.  Energy is more concentrated.  The southern hemisphere is opposite the northern hemisphere.

10. Special Days of the Year  Summer solstice: Sun farthest north.  Autumnal equinox: Sun on the equator, moving southward.  Winter solstice: Sun farthest south.  Vernal equinox: Sun on the equator, moving northward.

11. Lecture – Tutorial Path of the Sun: pg 89 Work with a partner! Read the instructions and questions carefully. Discuss the concepts and your answers with each other. Come to a consensus answer you both agree on. If you get stuck or are not sure of your answer, ask another group. If you get really stuck or don’t understand what the Lecture Tutorial is asking, ask one of us for help.

12. i_Clicker Question ClassAction: Questions: Coords & Motion: Sun Path 1

13. i_Clicker Question ClassAction: Questions: Coords & Motion: Sun Shadow

14. I Realize this is Like Trying to Drink from a Fire Hose

15. Lecture – Tutorial Seasons: pg. 93 Work with a partner! Yada Yada Yada … This one is homework

16. Stuff in Chapter 2 Coordinates Position Daily Motion (spin of Earth on its axis) Visibility of the sky Year Motion (Earth orbits the Sun) Seasons (tilt of the Earth’s axis) Precession of the equinoxes Motion and phases of the Moon Eclipses

17. Precession  Currently, the north celestial pole is near the bright star Polaris.  Earth’s axis wobbles with a period of 26,000 years.  Location of the poles slowly shifts.

18.  Earth wobbles like a top, slowly.  Since the axis shifts, the equator shifts.  Positions of the equinoxes precess as well.