Lec 7 - Lecture 7 5 Oct. 2010 Motions of the Planets...

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Lecture 7 5 Oct. 2010 Motions of the Planets Stellar Parallax and implications. Orbits Tides Precession
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Announcements 1. Students must SIGN UP for planetarium shows before attending. Students who show up without signing up will be turned away due to space limitations. 2. Prof. Reid will be holding a midterm review session : DATE: Wednesday, October 6 TIME: 4:00-5:30 p.m. LOCATION: O.I.S.E. Room G162 (the huge auditorium) 3. IMAX show tickets are still available during office hours. Prof. Reid be outside the lecture at the end today again to sell them (front right door as you see it). 4. Assignment 4 will be out today or tonight.
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The Ancient Mystery of the Planets What was once so mysterious about planetary motion in our sky? Why did the ancient Greeks reject the real explanation for planetary motion? Our goals for learning:
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Planets Known in Ancient Times Mercury difficult to see; always close to Sun in sky Venus very bright when visible; morning or evening “star” Mars noticeably red Jupiter very bright Saturn moderately bright
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What was once so mysterious about planetary motion in our sky? Planets usually move slightly eastward from night to But sometimes they go westward relative to the stars for a few weeks: apparent retrograde motion JUPITER 2008-2009 Mars 2003
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EAST WEST MARS THROUGH OPPOSITION
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We see apparent retrograde motion when we pass by a planet in its orbit. Months
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Demonstration of Retrograde Motion
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Clicker Question I n the previous diagram, to imitate the Solar System should the inside person be walking: A) More quickly B) At the same speed C) More slowly
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Voting
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Clicker Question I n the previous diagram, to imitate the Solar System should the inside person be walking: A) More quickly B) At the same speed C) More slowly
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Explaining Apparent Retrograde Motion Easy for us to explain: occurs when we “lap” another planet (or when Mercury or Venus laps us) But very difficult to explain if you think that Earth is the center of the universe! In fact, the ancients considered but rejected the correct explanation (Sun-centred “universe”).
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Explaining retrograde motion of outer planets in the Earth-centred model of the Universe . .. the kludge of “epicycles”.
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reject the real explanation for planetary motion? Their inability to observe
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This note was uploaded on 10/08/2011 for the course AST 101 taught by Professor Mochnacki/abraham during the Fall '08 term at University of Toronto.

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Lec 7 - Lecture 7 5 Oct. 2010 Motions of the Planets...

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