Astronomy 1010 Planetary Astronomy Fall_2015 Day-7

Course Announcements Read Chapter 2 How is the lunar observing going? This week: Dark Night Observing on Thur. 9/10 1 st Quarter night – Mon. 9/21 -7:30pm – on campus Exam 1: Fri. Sept. 18 or Mon. Sept. 21 This weekend: Thurs. - Sat. – Riverfest This week: National Adopt a pet week Next Week: APSU-OUR: Research & Creative Activity Week. Events in the library 2:30-3:30 every day.APSU-OUR

Definitions & Terms -1 Cat: An animal that was once revered as a God by the Egyptians. Cats have not forgotten this. Orbit: The path of one body (e.g. a planet) around another (e.g. the Sun in our solar system). Orbital Period: The time it takes an orbit to occur.

Concept Quiz In what direction is the observer facing? A) toward the South B) toward the North C) toward the East D) toward the West Celestial Sphere Celestial Sphere Rotation Celestial Sphere Star A Star B Horizon

Concept Quiz Where would the observer look to see the star indicated by the arrow? A. High in the Northeast B. High in the Southeast C. High in the Northwest D. High in the Southwest Celestial Sphere Celestial Sphere Rotation Celestial Sphere Star A Star B Horizon

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

Nightly Motion of the Stars Imagine looking toward the North. What do stars appear to do over the course of an evening?

Nightly Motion of the Stars Looking North: Stars appear to move counter- clockwise around the stationary North Star (Polaris) – we call these circumpolar stars.

Earth’s rotation causes the Sun, Planets, Moon and stars to appear to move when viewed from Earth Photo: Dr. Spencer Buckner

Nightly Motion of the Stars Celestial Sphere Celestial Sphere Rotation Celestial Sphere Star A Star B Figure 2 Horizon

Circumpolar Stars Circumpolar stars seem to move counter-clockwise around the stationary North Star. These constellations and stars are visible any night of the year in the NORTHERN sky because they never rise or set! Examples: Ursa Major, Ursa Minor, Draco, Cepheus, and Cassiopeia

Tutorial: Motion – p.3 Work with a partner Read the instructions and questions carefully Discuss 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

Concept Quiz Imagine that from your current location you observe a star rising directly in the east. When this star reaches its highest position above the horizon, where will it be? A. high in the northern sky B. high in the southern sky C. high in the western sky D. directly overhead

How long did this picture take and WHY do you think that? 3-minute Essay