Earth/Moon as seen from Mars

Bit of Administration …. HomeworksHomeworks –Bless, pp –BNSV, pp Observing LabObserving Lab –Nice Work on Lab 1 ! –Start Lab 2 on Saturday Timing Matters!Timing Matters! 10 minutes every clear night for two weeks10 minutes every clear night for two weeks

M S J S M E Not to scale! V

The Transition to A Heliocentric Cosmology Copernicus1500 ADCopernicus1500 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 PlanetCopernicusModern Mercury Venus Earth Mars Jupiter Saturn Distances Measured in Astronomical Units Distances Measured in Astronomical Units

M S J S M E Not to scale! V

The Transition to A Heliocentric Cosmology Summer Winter Copernicus –Non-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 Copernicus1500 ADCopernicus1500 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

The Transition to A Heliocentric Cosmology Copernicus1500 ADCopernicus1500 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 parallaxNo 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 Galileo1600 ADGalileo1600 AD –Siderius Nuncius 1610 (Star Messenger) (Star Messenger)

The Triumph of Heliocentric Cosmology Galileo1600 ADGalileo1600 AD –Siderius Nuncius 1610 (Star Messenger) (Star Messenger) –Application of the Telescope Revolutionary impact of new technologyRevolutionary impact of new technology

The Triumph of Heliocentric Cosmology Galileo1600 ADGalileo1600 AD –Siderius Nuncius 1610 (Star Messenger) (Star Messenger) –Moon Craters, mountains, valleysCraters, mountains, valleys –Earth-like, not perfect or celestial

The Triumph of Heliocentric Cosmology Galileo1600 ADGalileo1600 AD –Siderius Nuncius 1610 (Star Messenger) (Star Messenger) –Moon Craters, mountains, valleysCraters, mountains, valleys –Earth-like, not perfect or celestial –Sun SunspotsSunspots RotationRotation

The Triumph of Heliocentric Cosmology Galileo1600 ADGalileo1600 AD –Siderius Nuncius 1610 (Star Messenger) (Star Messenger) –Moon Craters, mountains, valleysCraters, mountains, valleys –Earth-like, not perfect or celestial –Sun SunspotsSunspots RotationRotation –Saturn Not sphericalNot spherical

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: oOoI 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 Galileo1600 ADGalileo1600 AD –Siderius Nuncius 1610 (Star Messenger) (Star Messenger) –Moon Craters, mountains, valleysCraters, mountains, valleys –Earth-like, not perfect or celestial –Sun SunspotsSunspots RotationRotation –Saturn Not sphericalNot spherical –Milky Way Knowledge unknown to ancients or naked eyeKnowledge unknown to ancients or naked eye

The Triumph of Heliocentric Cosmology Galileo1600 ADGalileo1600 AD –Siderius Nuncius 1610 (Star Messenger) (Star Messenger) –Moon Craters, mountains, valleysCraters, mountains, valleys –Earth-like, not perfect or celestial –Sun SunspotsSunspots RotationRotation –Saturn Not sphericalNot spherical –Milky Way Knowledge unknown to ancients or naked eyeKnowledge unknown to ancients or naked eye –Jupiter’s Moons Microcosm of Copernican Solar SystemMicrocosm of Copernican Solar System

The Triumph of Heliocentric Cosmology Galileo1600 ADGalileo1600 AD –Siderius Nuncius 1610 (Star Messenger) (Star Messenger) –Moon Craters, mountains, valleysCraters, mountains, valleys –Earth-like, not perfect or celestial –Sun SunspotsSunspots RotationRotation –Milky Way Knowledge unknown to ancients or naked eyeKnowledge unknown to ancients or naked eye –Jupiter’s Moons Microcosm of Copernican Solar SystemMicrocosm of Copernican Solar System

The Triumph of Heliocentric Cosmology Galileo1600 ADGalileo1600 AD –Siderius Nuncius 1610 (Star Messenger) (Star Messenger) –Moon Craters, mountains, valleysCraters, mountains, valleys –Earth-like, not perfect or celestial –Sun SunspotsSunspots RotationRotation –Saturn Not sphericalNot spherical –Milky Way Knowledge unknown to ancients or naked eyeKnowledge unknown to ancients or naked eye –Jupiter’s Moons Microcosm of Copernican Solar SystemMicrocosm of Copernican Solar System –Phases of Venus Unexplainable in Ptolemaic SystemUnexplainable in Ptolemaic System

VenusPhases Ptolemy Copernicus

The Earth would be seen to have phases from a life form on A) Mercury A) Mercury B) Mars B) Mars C) The Sun C) The Sun D) No planet in the Solar System D) No planet in the Solar SystemConcepTest!

Earth/Moon as seen from Mars

The Triumph of Heliocentric Cosmology Galileo1600 ADGalileo1600 AD –Siderius Nuncius 1610 (Star Messenger) (Star Messenger) 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 Brahe1575 ADTycho Brahe1575 AD –Finest observer since Hipparchus Discovered Nova Stella (“new star”)Discovered Nova Stella (“new star”) –Changes in the heavens Showed Comet to be 6x further than MoonShowed Comet to be 6x further than Moon –Not atmospheric –“Shattered the crystalline spheres” Couldn’t Detect Stellar ParallaxCouldn’t Detect Stellar Parallax –Rejected Copernicus! Made Extensive Precise MeasurementsMade Extensive Precise Measurements of Planetary Positions of Planetary Positions

The Triumph of Heliocentric Cosmology Tycho Brahe1575 ADTycho Brahe1575 AD –Finest observer since Hipparchus Discovered Nova Stella (“new star”)Discovered Nova Stella (“new star”) –Changes in the heavens Showed Comet to be 6x further than MoonShowed Comet to be 6x further than Moon –Not atmospheric –“Shattered the crystalline spheres” Couldn’t Detect Stellar ParallaxCouldn’t Detect Stellar Parallax –Rejected Copernicus! Made Extensive Precise MeasurementsMade Extensive Precise Measurements of Planetary Positions of Planetary Positions Did not abandon Uniform Circular MotionDid not abandon Uniform Circular Motion

The Triumph of Heliocentric Cosmology Kepler1600 ADKepler1600 AD –Primacy of (Tycho Brahe’s) observations –Physical machine that mimics the skies precisely

Kepler’s Three Laws of Planetary Motion 1.The Orbits of the Planets are Ellipses with the Sun at One Focus

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.ConcepTest!

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

Kepler’s Three Laws of Planetary Motion 2.The Line Joining The Sun and A Planet Sweeps Out Equal Areas in Equal Times 30 days

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

Kepler’s Three Laws of Planetary Motion 3.The Square of a Planet’s Period (P in Years) Equals the Cube of the Semi-Major Axis of its Orbit (A in AU) P 2 = A 3

A 1