aristotlenewton - Announcements From Aristotle to Newton...

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Announcements First Homework is Due today TA (Ken Obenberger) will be in RH111 4:30-5:30pm Ken’s e-mail is [email protected] Sept 2 is last day to drop with refund If your clicker is not registered and you are not set up in Mastering Astronomy by Sept 2 you will be dropped from this course From Aristotle to Newton The history of our knowledge about the Solar System (and the universe to some extent) from ancient Greek times through to the beginnings of modern physics. Clicker Review: What time of day does the first quarter moon set? A: 6am B: noon C: 6pm D: midnight E: Never sets Clicker Question: Who was the first person to use a telescope to make astronomical discoveries? A: Aristotle B: Brahe C: Kepler D: Gallileo E: Newton "Geocentric Model" of the Solar System Aristotle vs. Aristarchus (3 rd century B.C.) Aristotle : Sun, Moon, Planets and Stars rotate around fixed Earth. Ancient Greek astronomers knew of Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn. Aristotle : But there's no wind or parallax. Difficulty with Aristotle's "Geocentric" model: "Retrograde motion of the planets". Aristarchus : Used geometry of eclipses to show Sun bigger than Earth (and Moon smaller), so guessed that Earth orbits the Sun. Also guessed Earth spins on its axis once a day => apparent motion of stars. Aristarchus : Yes, sir Planets generally move in one direction relative to the stars, but sometimes they appear to loop back. This is "retrograde motion".
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But if you support geocentric model, you must attribute retrograde motion to actual motions of planets, leading to loops called “epicycles”. Ptolemy's geocentric model (A.D. 140)
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aristotlenewton - Announcements From Aristotle to Newton...

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