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Earth/Moon as seen from Mars. Bit of Administration …. Homeworks Bless, pp. 105-139 BNSV, pp. 70-83 Observing Lab Nice Work on Lab 1 ! Start Lab 2 on Saturday Timing Matters! 10 minutes every clear night for two weeks. J. M. S. M. V. S. E. Not to scale!.
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Bit of Administration …. • Homeworks • Bless, pp. 105-139 • BNSV, pp. 70-83 • Observing Lab • Nice Work on Lab 1 ! • Start Lab 2 on Saturday • Timing Matters! • 10 minutes every clear night for two weeks
J M S M V S E Not to scale!
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 • Stars Very Far Away - No Parallax • Geometric Distances to the Planets 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 Distances Measured in Astronomical Units
J M S M V S E Not to scale!
Hipparchus Copernicus Summer Summer Winter 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 • Stars Very Far Away - No Parallax • Geometric Distances to the Planets • Non-Uniform Motion of Sun, Moon and Planets • Retained Uniform Circular Motion, thus required Hipparchus’ epicyles!
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 - arguments were aesthetic and philosophical
The Triumph of Heliocentric Cosmology • Siderius Nuncius 1610 (Star Messenger) • Galileo 1600 AD
The Triumph of Heliocentric Cosmology • Siderius Nuncius 1610 (Star Messenger) • Application of the Telescope • Revolutionary impact of new technology • Galileo 1600 AD
The Triumph of Heliocentric Cosmology • Siderius Nuncius 1610 (Star Messenger) • Moon • Craters, mountains, valleys • Earth-like, not perfect or celestial • Galileo 1600 AD
The Triumph of Heliocentric Cosmology • Siderius Nuncius 1610 (Star Messenger) • Moon • Craters, mountains, valleys • Earth-like, not perfect or celestial • Sun • Sunspots • Rotation • Galileo 1600 AD
The Triumph of Heliocentric Cosmology • Siderius Nuncius 1610 (Star Messenger) • Moon • Craters, mountains, valleys • Earth-like, not perfect or celestial • Sun • Sunspots • Rotation • Saturn • Not spherical • Galileo 1600 AD
I discovered another very strange wonder, which I should like to make known to their Highnesses . . . , keeping it secret, however, until the time when my work is published . . . . the star of Saturn is not a single star, but is a composite of three, which almost touch each other, never change or move relative to each other, and are arranged in a row along the zodiac, the middle one being three times larger than the lateral ones, and they are situated in this form: oOo
The Triumph of Heliocentric Cosmology • Siderius Nuncius 1610 (Star Messenger) • Moon • Craters, mountains, valleys • Earth-like, not perfect or celestial • Sun • Sunspots • Rotation • Saturn • Not spherical • Milky Way • Knowledge unknown to ancients or naked eye • Galileo 1600 AD
The Triumph of Heliocentric Cosmology • Siderius Nuncius 1610 (Star Messenger) • Moon • Craters, mountains, valleys • Earth-like, not perfect or celestial • Sun • Sunspots • Rotation • Saturn • Not spherical • Milky Way • Knowledge unknown to ancients or naked eye • Jupiter’s Moons • Microcosm of Copernican Solar System • Galileo 1600 AD
The Triumph of Heliocentric Cosmology • Siderius Nuncius 1610 (Star Messenger) • Moon • Craters, mountains, valleys • Earth-like, not perfect or celestial • Sun • Sunspots • Rotation • Milky Way • Knowledge unknown to ancients or naked eye • Jupiter’s Moons • Microcosm of Copernican Solar System • Galileo 1600 AD
The Triumph of Heliocentric Cosmology • Siderius Nuncius 1610 (Star Messenger) • Moon • Craters, mountains, valleys • Earth-like, not perfect or celestial • Sun • Sunspots • Rotation • Saturn • Not spherical • Milky Way • Knowledge unknown to ancients or naked eye • Jupiter’s Moons • Microcosm of Copernican Solar System • Phases of Venus • Unexplainable in Ptolemaic System • Galileo 1600 AD
Venus Phases Copernicus Ptolemy
ConcepTest! • The Earth would be seen to have phases from a life form on • A) Mercury • B) Mars • C) The Sun • D) No planet in the Solar System
The Triumph of Heliocentric Cosmology • Siderius Nuncius 1610 (Star Messenger) • Galileo 1600 AD Galileo too did not abandon Uniform Circular Motion, and did not embrace his contemporary Kepler Galileo’s Problems with the Church were Self-Generated A Dialog Concerning the Two Chief Worlds
The Triumph of Heliocentric Cosmology • Tycho Brahe 1575 AD • Finest observer since Hipparchus • Discovered Nova Stella (“new star”) • Changes in the heavens • Showed Comet to be 6x further than Moon • Not atmospheric • “Shattered the crystalline spheres” • Couldn’t Detect Stellar Parallax • Rejected Copernicus! • Made Extensive Precise Measurements of Planetary Positions
The Triumph of Heliocentric Cosmology • Tycho Brahe 1575 AD • Finest observer since Hipparchus • Discovered Nova Stella (“new star”) • Changes in the heavens • Showed Comet to be 6x further than Moon • Not atmospheric • “Shattered the crystalline spheres” • Couldn’t Detect Stellar Parallax • Rejected Copernicus! • Made Extensive Precise Measurements of Planetary Positions • Did not abandon Uniform Circular Motion
The Triumph of Heliocentric Cosmology • Kepler 1600 AD • Primacy of (Tycho Brahe’s) observations • Physical machine that mimics the skies precisely
Kepler’s Three Laws of Planetary Motion • The Orbits of the Planets are Ellipses with the Sun at One Focus
ConcepTest! • Which of the following orbits has the smallest eccentricity? • A) B) C) • D) All have the same eccentricity.
ConcepTest! • Which of the following orbits has the smallest semi-major axis? • A) B) C) • D) All have the same semi-major axis.
The Orbits of the Planets are Ellipses with the Sun at One Focus
Kepler’s Three Laws of Planetary Motion • The Line Joining The Sun and A Planet Sweeps Out Equal Areas in Equal Times 30 days 30 days
The Line Joining The Sun and A Planet Sweeps Out Equal Areas in Equal Times
Kepler’s Three Laws of Planetary Motion • The Square of a Planet’s Period (P in Years) Equals the Cube of the Semi-Major Axis of its Orbit (A in AU) P2 = A3
A 1 P 2 = A 3