Earth/Moon as seen from Mars

Earth/Moon as seen from MarsEarth/Moon as seen from Mars

Bit of Administration ….Bit of Administration ….

• HomeworksHomeworks– Bless, pp. 105-139Bless, pp. 105-139– BNSV, pp. 70-83BNSV, pp. 70-83

• Observing LabObserving Lab– Nice Work on Lab 1 !Nice Work on Lab 1 !– Start Lab 2 on SaturdayStart Lab 2 on Saturday

• Timing Matters!Timing Matters!

• 10 minutes every clear night for two weeks10 minutes every clear night for two weeks

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The Transition to A Heliocentric CosmologyThe Transition to A Heliocentric Cosmology• CopernicusCopernicus 1500 AD1500 AD

– Daily Motion due to Earth RotationDaily Motion due to Earth Rotation– Solar Motion due to Earth RevolutionSolar Motion due to Earth Revolution– Prograde Motion of Moon and Planets due to their Orbital MotionPrograde Motion of Moon and Planets due to their Orbital Motion– Retrograde MotionRetrograde Motion– Maximum Elongations of Mercury and VenusMaximum Elongations of Mercury and Venus– Stars Very Far Away - No ParallaxStars Very Far Away - No Parallax– Geometric Distances to the PlanetsGeometric Distances to the Planets

PlanetPlanet CopernicusCopernicus ModernModern

MercuryMercury 0.38 0.38 0.39 0.39VenusVenus 0.72 0.72 0.72 0.72EarthEarth 1.001.00 1.00 1.00MarsMars 1.52 1.52 1.52 1.52JupiterJupiter 5.22 5.22 5.07 5.07SaturnSaturn 9.07 9.07 9.54 9.54

Distances Measured in Astronomical UnitsDistances Measured in Astronomical Units

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The Transition to A Heliocentric CosmologyThe Transition to A Heliocentric Cosmology

Summer Winter

Copernicus

– Non-Uniform Motion of Sun, Moon and PlanetsNon-Uniform Motion of Sun, Moon and Planets• Retained Uniform Circular Motion, thus required Hipparchus’ epicyles!Retained Uniform Circular Motion, thus required Hipparchus’ epicyles!

Summer Winter

Hipparchus

• CopernicusCopernicus 1500 AD1500 AD– Daily Motion due to Earth RotationDaily Motion due to Earth Rotation– Solar Motion due to Earth RevolutionSolar Motion due to Earth Revolution– Prograde Motion of Moon and Planets due to their Orbital Prograde Motion of Moon and Planets due to their Orbital

MotionMotion– Retrograde MotionRetrograde Motion– Maximum Elongations of Mercury and VenusMaximum Elongations of Mercury and Venus– Stars Very Far Away - No ParallaxStars Very Far Away - No Parallax– Geometric Distances to the PlanetsGeometric Distances to the Planets

The Transition to A Heliocentric CosmologyThe Transition to A Heliocentric Cosmology• CopernicusCopernicus 1500 AD1500 AD

– Daily Motion due to Earth RotationDaily Motion due to Earth Rotation– Solar Motion due to Earth RevolutionSolar Motion due to Earth Revolution– Prograde Motion of Moon and Planets due to their Orbital MotionPrograde Motion of Moon and Planets due to their Orbital Motion– Retrograde MotionRetrograde Motion– Maximum Elongations of Mercury and VenusMaximum Elongations of Mercury and Venus– Geometric Distances to the Planets (example for Venus)Geometric Distances to the Planets (example for Venus)– Star Very Far AwayStar Very Far Away

• No observed parallaxNo observed parallax

– Non-Uniform Motion of Sun, Moon and PlanetsNon-Uniform Motion of Sun, Moon and Planets

In the 1500’s, the Copernican system In the 1500’s, the Copernican system did notdid not predict positions predict positions better than the highly refined Ptolemaic systembetter than the highly refined Ptolemaic system

The Copernicans had no proof - The Copernicans had no proof - arguments were aesthetic and philosophicalarguments were aesthetic and philosophical

The Triumph of Heliocentric CosmologyThe Triumph of Heliocentric Cosmology• GalileoGalileo 1600 AD1600 AD

– Siderius Nuncius Siderius Nuncius 16101610 ((Star MessengerStar Messenger))



– Application of the TelescopeApplication of the Telescope• Revolutionary impact of new technologyRevolutionary impact of new technology



– MoonMoon• Craters, mountains, valleys Craters, mountains, valleys

– Earth-like, not perfect or celestialEarth-like, not perfect or celestial





– SunSun• SunspotsSunspots• RotationRotation

QuickTime™ and aYUV420 codec decompressorare needed to see this picture.






– SaturnSaturn• Not sphericalNot spherical

• I discovered another very strange wonder, which I I discovered another very strange wonder, which I should like to make known to their Highnesses . . . , should like to make known to their Highnesses . . . , keeping it secret, however, until the time when my keeping it secret, however, until the time when my work is published . . . . the star of Saturn is not a single work is published . . . . the star of Saturn is not a single star, but is a composite of three, which almost touch star, but is a composite of three, which almost touch each other, never change or move relative to each each other, never change or move relative to each other, and are arranged in a row along the zodiac, the other, and are arranged in a row along the zodiac, the middle one being three times larger than the lateral middle one being three times larger than the lateral ones, and they are situated in this form: oOoones, and they are situated in this form: oOo







– Milky WayMilky Way• Knowledge unknown to ancients or naked eyeKnowledge unknown to ancients or naked eye








– Jupiter’s MoonsJupiter’s Moons• Microcosm of Copernican Solar SystemMicrocosm of Copernican Solar System
















– Phases of VenusPhases of Venus• Unexplainable in Ptolemaic SystemUnexplainable in Ptolemaic System

VenusVenusPhasesPhases

PtolemyPtolemyCopernicusCopernicus

The Earth would be seen to have phases from a life form on The Earth would be seen to have phases from a life form on

A) MercuryA) Mercury B) MarsB) Mars C) The SunC) The Sun D) No planet in the Solar SystemD) No planet in the Solar System

ConcepTest!ConcepTest!

Earth/Moon as seen from MarsEarth/Moon as seen from Mars



Galileo too did not abandon Uniform Circular Motion,Galileo too did not abandon Uniform Circular Motion,and did not embrace his contemporary Keplerand did not embrace his contemporary Kepler

Galileo’s Problems with the Church were Self-GeneratedGalileo’s Problems with the Church were Self-GeneratedA Dialog Concerning the Two Chief WorldsA Dialog Concerning the Two Chief Worlds

The Triumph of Heliocentric CosmologyThe Triumph of Heliocentric Cosmology• Tycho BraheTycho Brahe 1575 AD1575 AD

– Finest observer since HipparchusFinest observer since Hipparchus

• Discovered Nova Stella (“new star”)Discovered Nova Stella (“new star”)– Changes in the heavensChanges in the heavens

• Showed Comet to be 6x further than MoonShowed Comet to be 6x further than Moon– Not atmosphericNot atmospheric– ““Shattered the crystalline spheres”Shattered the crystalline spheres”

• Couldn’t Detect Stellar ParallaxCouldn’t Detect Stellar Parallax– Rejected Copernicus!Rejected Copernicus!

• Made Extensive Precise MeasurementsMade Extensive Precise Measurements of Planetary Positionsof Planetary Positions

The Triumph of Heliocentric CosmologyThe Triumph of Heliocentric Cosmology• Tycho BraheTycho Brahe 1575 AD1575 AD

– Finest observer since HipparchusFinest observer since Hipparchus

• Discovered Nova Stella (“new star”)Discovered Nova Stella (“new star”)– Changes in the heavensChanges in the heavens

• Showed Comet to be 6x further than MoonShowed Comet to be 6x further than Moon– Not atmosphericNot atmospheric– ““Shattered the crystalline spheres”Shattered the crystalline spheres”

• Couldn’t Detect Stellar ParallaxCouldn’t Detect Stellar Parallax– Rejected Copernicus!Rejected Copernicus!

• Made Extensive Precise MeasurementsMade Extensive Precise Measurements of Planetary Positionsof Planetary Positions

• Did not abandon Uniform Circular MotionDid not abandon Uniform Circular Motion

The Triumph of Heliocentric CosmologyThe Triumph of Heliocentric Cosmology• KeplerKepler 1600 AD1600 AD

– Primacy of (Tycho Brahe’s) observationsPrimacy of (Tycho Brahe’s) observations– Physical machine that mimics the skies preciselyPhysical machine that mimics the skies precisely

Kepler’s Three Laws of Planetary Kepler’s Three Laws of Planetary MotionMotion

1.1. The Orbits of the Planets are Ellipses with the The Orbits of the Planets are Ellipses with the Sun at One FocusSun at One Focus

Which of the following orbits has the smallest eccentricity?

A) B) C)

D) All have the same eccentricity.


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 The Orbits of the Planets are Ellipses with the Sun at One FocusSun at One Focus


2.2. The Line Joining The Sun and A Planet The Line Joining The Sun and A Planet Sweeps Out Equal Areas in Equal TimesSweeps Out Equal Areas in Equal Times

30 days 30 days

The Line Joining The Sun and A Planet The Line Joining The Sun and A Planet Sweeps Out Equal Areas in Equal TimesSweeps Out Equal Areas in Equal Times


3.3. The Square of a Planet’s Period (P in Years) The Square of a Planet’s Period (P in Years) Equals the Cube of the Semi-Major Axis of its Equals the Cube of the Semi-Major Axis of its Orbit (A in AU)Orbit (A in AU)

PP22 = A = A33

P P 22 = A = A 33

A

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Earth/Moon as seen from Mars