1. Astronomy 1010 Planetary Astronomy Fall_2015 Day-10

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. 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

5. 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.

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

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. The Moon’s Motions Because the orbit is elliptical and not circular, the rotation speed doesn’t always match the orbital speed.

9. The Month? Full Moon to Full Moon takes 29.53 days

11. The Cycle of Lunar Phases

12. The moon does rotate. The moon takes the same amount of time to complete one rotation as it does to complete one orbit

13. The orbital period is not the same as the cycle of phases Cycle of phases: The synodic month 29.53 days The Orbital Period is the Sidereal Month: 27.32 days

14. Lecture – Tutorial Cause of Moon Phases: pg 81 Work with a partner! Read the instructions and questions carefully. Discuss the concepts and your answers with one another. 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.

15. i_Clicker Question ClassAction: Questions: Lunar Cycles: Phase Evolution; option 1

16. Lecture – Tutorial Predicting Moon Phases: pg 85 Work with a partner! Read the instructions and questions carefully. Discuss the concepts and your answers with one another. 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.