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C/2002 T7 (LINEAR)

C/2002 T7 (LINEAR). Bit of Administration …. Homeworks Due in lecture or by 3:45 on Friday at 6515 Sterling Error in Question 5: replace ‘3’ with ‘4’ Office Hours M 3:30-5:30 ==> 3:30 - 4:35 (Honors at 4:35) Observing Lab Continue Lab 3 Higher quality of recording data

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C/2002 T7 (LINEAR)

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  1. C/2002 T7 (LINEAR)

  2. Bit of Administration …. • Homeworks • Due in lecture or by 3:45 on Friday at 6515 Sterling • Error in Question 5: replace ‘3’ with ‘4’ • Office Hours • M 3:30-5:30 ==> 3:30 - 4:35 (Honors at 4:35) • Observing Lab • Continue Lab 3 • Higher quality of recording data • “You can’t get these labs wrong if you observe carefully”

  3. Hipparchus, The Great Observer • Hipparchus 150 BC (Island of Rhodes) • Cataloged Positions and Brightnesses of 850 Stars • Length of Month and Year, With Errors • Year accurate to 6 minutes, Month accurate to seconds • Precession (“of the equinoxes”)

  4. Precession

  5. Hipparchus • Hipparchus 150 BC (Island of Rhodes) • Cataloged Positions and Brightnesses of 850 Stars • Length of Month and Year, With Errors • Year Accurate to 6 minutes, Month accurate to seconds • Precession • Non-Uniform Motion of Sun (and Moon) • Solar Motion is faster in (northern) winter

  6. Hipparchus - Eccentric Circle, Uniform Circular Motion Winter Summer Epicycles Summer Winter Deferent Hipparchus - Earth-Centered, Uniform Circular Motion Evolution of Greek Cosmologies Platonic - Earth-Centered, Uniform Circular Motion

  7. Evolution of Greek Cosmologies • Hipparchus 150 BC (Island of Rhodes) • Cataloged Positions and Brightnesses of 850 Stars • Length of Month and Year, With Errors • Year Accurate to 6 minutes, Month accurate to seconds • Precession • Non-Uniform Motion of Sun and Moon • Solar motion is faster in (northern) winter • The “Eccentric Circle” • Primacy of observation over dogma • Inter-relation of observation and theory • The role of the aesthetic in understanding the universe

  8. Evolution of Greek Cosmologies • Ptolemy 140 AD “The Great Synthesizer” • Almagest 13 volumes, source of most Greek astronomy • Assume • Uniform Circular Motion • Earth Spherical, Stationary, Near Center • Account For • Daily Motion from East to West • Prograde (West to East) Motions of Sun, Moon, Planets • Retrograde Motion of Planets • Mercury < 28o, Venus < 46o from Sun • Non-Uniformity in Rates of Prograde Motions • And everything else!

  9. M 28o 46o E J V M S S Daily

  10. Evolution of Greek Cosmologies • Ptolemy 140 AD “The Great Synthesizer” • Epicycles ==> Retrograde Motion

  11. Evolution of Greek Cosmologies • Ptolemy 140 AD “The Great Synthesizer” • Epicycles ==> Retrograde Motion 4 3 1 1/1 2 3 2 5/1 4 1

  12. Evolution of Greek Cosmologies • Ptolemy 140 AD “The Great Synthesizer” • Epicycles ==> Retrograde Motion

  13. M E J V M S S Daily

  14. Evolution of Greek Cosmologies • Ptolemy 140 AD “The Great Synthesizer” • Equant ==> Non-Uniform Motions Uniform Angular Motion Equant

  15. Evolution of Greek Cosmologies • Ptolemy 140 AD “The Great Synthesizer” • Equant ==> Non-Uniform Motions

  16. Evolution of Greek Cosmologies • Ptolemy 140 AD “The Great Synthesizer” • Almagest 13 volumes, source of most Greek astronomy • Assume • Uniform Circular Motion • Earth Spherical, Stationary, Near Center • Account For • Daily Motion from East to West • Prograde (West to East) Motions of Sun, Moon, Planets • Retrograde Motion of Planets • Mercury < 28o, Venus < 46o from Sun • Non-Uniformity in Rates of Prograde Motions • And everything else! Ptolemaic predictions were only accurate to about 5o A collection of recipes - not an Aristotelian machine.

  17. The Transition to A Heliocentric Cosmology • No fundamentally new ideas in astronomy for 1400 yr; Greek astronomy preserved in Islamic world during the European Dark Ages. • Copernicus 1500 AD • De Revolutionibus Orbium Coelstium 1543 (On the Revolution of the Celestial Spheres) • Motivations • Philosophical Objections • Ptolemaic cosmology wasn’t a machine that could be built • Equant violated Uniform Circular Motion • Fundamentally an Aristotelian world view • NOT inaccuracy or inadequacy of geocentric system • NOT Sun “should” be at the center • Assumptions • Heliocentric • Earth rotates once every 24 hours • Earth-Sun distance << Earth-Stars distance • Uniform Circular Motion

  18. J M S M V S E Not to scale!

  19. The Transition to A Heliocentric Cosmology • Copernicus 1500 AD • Daily Motion due to Earth rotation • Solar Motion due to Earth revolution around the Sun • Prograde Motion of Moon and Planets due to their orbital motions • More correctly for the planets, their motions relative to the moving Earth • Retrograde Motion of Planets

  20. Copernicus Retrograde Motion of Outer Planets

  21. M V E S The Transition to A Heliocentric Cosmology • Copernicus 1500 AD • Daily Motion due to Earth Rotation • Solar Motion due to Earth Revolution • Prograde Motion of Moon and Planets due to their Orbital Motion • Retrograde Motion of Planets • Maximum Elongations of Mercury and Venus 28o 46o

  22. V M V E S 46o S E The Transition to A Heliocentric Cosmology • Copernicus 1500 AD • Daily Motion due to Earth Rotation • Solar Motion due to Earth Revolution • Prograde Motion of Moon and Planets due to their Orbital Motion • Retrograde Motion • Maximum Elongations of Mercury and Venus • Geometric Distances to the Planets (example for Venus) 46o VS = ES * sin 46o = (1 AU) * sin 46o 1 Astronomical Unit = Earth-Sun Distance

  23. The Transition to A Heliocentric Cosmology • Copernicus 1500 AD • Daily Motion due to Earth Rotation • Solar Motion due to Earth Revolution • Prograde Motion of Moon and Planets due to their Orbital Motion • Retrograde Motion • Maximum Elongations of Mercury and Venus • Geometric Distances to the Planets (example for Venus) Planet Copernicus Modern Mercury 0.38 0.39 Venus 0.72 0.72 Earth 1.00 1.00 Mars 1.52 1.52 Jupiter 5.22 5.07 Saturn 9.07 9.54

  24. Epicycles Summer Winter The Transition to A Heliocentric Cosmology • Copernicus 1500 AD • Daily Motion due to Earth Rotation • Solar Motion due to Earth Revolution • Prograde Motion of Moon and Planets due to their Orbital Motion • Retrograde Motion • Maximum Elongations of Mercury and Venus • Geometric Distances to the Planets (example for Venus) • Star Very Far Away • No observed parallax • Non-Uniform Motion of Sun, Moon and Planets • Retained uniform circular motion!

  25. M V S J M E S Not to scale!

  26. The Transition to A Heliocentric Cosmology • Copernicus 1500 AD • Daily Motion due to Earth Rotation • Solar Motion due to Earth Revolution • Prograde Motion of Moon and Planets due to their Orbital Motion • Retrograde Motion • Maximum Elongations of Mercury and Venus • Geometric Distances to the Planets (example for Venus) • Star Very Far Away • No observed parallax • Non-Uniform Motion of Sun, Moon and Planets In the 1500’s, the Copernican system did not predict positions better than the highly refined Ptolemaic system The Copernicans had no proof - the arguments were aesthetic and religious

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