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Lec03-Jan25[1]

# Lec03-Jan25[1] - Astro 109 Lecture 3 Understanding the Sky...

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Unformatted text preview: 1/25/11 Astro 109 Lecture 3: Understanding the Sky Jan. 25 [email protected] about reading or homework? Jan. 25 Quiz [email protected] #1 The [email protected] of the Earth's [email protected] axis onto the sky are called the A. B. C. D. E. [email protected] poles [email protected] zeniths [email protected] equator zodiac Quiz [email protected] #2 True or false? The Sun passes through your zenith every day. A. true B. false Jan. 25 Jan. 25 Quiz [email protected] #3 The [email protected] and equinoxes are mainly associated with A. B. C. D. E. the path of the Sun through the sky. the seasons. the distance of the Earth from the Sun. both A and B. all three A, B, and C. Key Concepts [email protected] in the sky Earth's @lt <--> seasons terminology: zenith, meridian [email protected] equator, [email protected] equinox, [email protected] Jan. 25 Jan. 25 1 1/25/11 Thought [email protected] This picture of Earth was taken by the Galileo spacecraY. In what month was it taken? A. B. C. D. E. March June September December There is not enough [email protected] to tell. Terminology for local sky Jan. 25 Jan. 25 Sun moves--throughout day and year The Analemma Jan. 25 Jan. 25 2001-2010 Anthony [email protected] Stars move, too Earth rotates Jan. 25 Jan. 25 h^p://www.planetary.org/explore/topics/earth/[email protected]_galileo_e1.mov 2 1/25/11 Discussion [email protected] What was the [email protected] of this @me-lapse photograph? A. 1 minute B. 10 minutes C. 1 hour D. 6 hours E. 12 hours Earth's sky = [email protected] Sphere Jan. 25 Jan. 25 Local sky vs. [email protected] sphere: Observer at north pole Observer at equator Jan. 25 Jan. 25 Observer in New Brunswick Discussion [email protected] The Sun rises in the east and sets in the west. Which of the following statements about the stars is true, as seen from New Brunswick? A. All stars rise in the east and set in the west. B. Some stars rise in the east and set in the west, but others are visible all night. C. All stars rise in the west and set in the east. D. Some stars rise in the west and set in the east, but others are visible all night. E. None of the above. Jan. 25 Jan. 25 3 1/25/11 Earth's @lt h^p://www.planetary.org/explore/topics/earth/[email protected]_galileo.mov (a) [email protected] to [email protected] sphere (b) [email protected] to [email protected] (i.e., Sun) Jan. 25 Earth's @lt and the seasons Jan. 25 Jan. 25 Seasons and Sun's path across sky Summer [email protected]: highest path; rise and set furthest north; long day, short night Discussion [email protected] Suppose the date is March 21 and the Sun passes through your zenith at noon. Where are you? A. B. C. D. E. the equator (0 [email protected]) the Tropic of Cancer (23.5N [email protected]) the Tropic of Capricorn (23.5S [email protected]) the [email protected] Circle (66.5N [email protected]) New Brunswick, NJ (40N [email protected]) Winter [email protected]: lowest path; rise and set furthest south; short day, long night Equinoxes: Sun rises due east and sets due west; equal day and night Jan. 25 Jan. 25 4 1/25/11 Seasonal changes are [email protected] at high [email protected] Why doesn't distance from Sun ma^er? Path of Sun on summer [email protected] at the [email protected] Circle. Jan. 25 Jan. 25 Change in distance is small (3%), and is overwhelmed by effects of axis @lt Precession Discussion [email protected] This picture of Earth was taken by the Galileo spacecraY. In what month was it taken? A. B. C. D. E. March June September December There is not enough [email protected] to tell. Jan. 25 [email protected] of [email protected] north changes (slowly) --> Polaris won't always be the North Star Jan. 25 5 ...
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