Astronomy 1020 Stellar Astronomy Spring_2015 Day-6

Course Announcements Smartworks Chapter 2: Start on – Grades will be downloaded sometime this coming weekend … hop to it. 1 st set of Dark Sky observing nights: Wed. Feb. 11 & Tues. Feb. 17

Celestial Sphere Celestial Sphere Rotation Celestial Sphere Star A Star B Figure 2 Horizon Position

Tutorial: Position – p.1 Work with a partner Read the instructions and questions carefully Talk to each other and discuss your answers with each 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 as 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

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

How long did it take to get this picture?

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

Celestial Sphere Rotation North Star Star A Star B Earth’s Equator Figure 1 Celestial Sphere Celestial Sphere Rotation Star A Star B Figure 2 Horizon Rotation

Why does the sky change with your location? As you move away from the pole your horizon moves with you but the locations of the celestial poles and celestial equator remains the same

Time Systems We live on Solar Time (time kept by the Sun) Our watches keep Mean Solar Time (24 hours/day) The stars keep Sidereal Time (~23h 56m per day) The 4 minute difference is due to the Earth’s orbital motion around the Sun. We reference Greenwich Mean Time (GMT, UT, TAI1) Clarksville is GMT-6 (5 during daylight savings time)

Why does the sky change over the course of a year? As we orbit the sun the direction opposite the sun changes and we only see the stars when the sun is not up

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