Course Goals What is Science? What is modern astronomy? What do we know about the Universe? How do...
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Transcript of Course Goals What is Science? What is modern astronomy? What do we know about the Universe? How do...
Course GoalsCourse Goals
What is Science?What is Science?
What is modern What is modern astronomy?astronomy?
What do we know about What do we know about the Universe?the Universe?
How do we know what How do we know what we know?we know?
Why Study Science?Why Study Science?
Scientific Method:Scientific Method:RigorousRigorous investigation involving investigation involving careful careful observationobservation, the formulation , the formulation of of hypotheseshypotheses, and , and experimentationexperimentation to test those to test those hypotheses. hypotheses.
Science:Science: The application of the The application of the Scientific MethodScientific Method to the to the natural world.natural world.
ScienceScience
Astronomy:Astronomy: The scientific investigation of The scientific investigation of astronomical phenomena.astronomical phenomena.
The Scientific MethodThe Scientific Method
The critical element is The critical element is
Experimental ProofExperimental Proof
Scientific TheoryScientific Theory
It’s It’s justjust a a theory!theory!
Scientific theory is not Scientific theory is not mere conjecture.mere conjecture.
Missing KeysMissing Keys
Sundials to tell the time of Sundials to tell the time of dayday
Telling TimeTelling Time
Predicting the SeasonsPredicting the Seasons
The Power of the GodsThe Power of the Gods
Ancient GreeceAncient Greece
First to create First to create theoretical theoretical models of models of naturenature
A HypothesisA HypothesisThe heavens are The heavens are perfect and perfect and unchanging.unchanging.
~Aristotle~Aristotle
Except…Except…The crystal spheres can’t explain The crystal spheres can’t explain
Retrograde MotionRetrograde Motion
The Ptolemaic ModelThe Ptolemaic Model
Ptolemy is now noticeably Ptolemy is now noticeably inaccurateinaccurate
An Alternative ModelAn Alternative Model
Sun centered model, Sun centered model, 15431543
•Simple retrograde Simple retrograde solutionsolution
•Simple orbital Simple orbital period calculationperiod calculation
•Position Position predictions predictions stillstill inaccurate.inaccurate.
Nicholas CopernicusNicholas Copernicus
New ObservationsNew Observations
Tycho Tycho BraheBrahe
Took 2 decades worth Took 2 decades worth of naked eye planet of naked eye planet observationsobservations
Accuracy to within 1 Accuracy to within 1 minute of arcminute of arc
ABCDABCDWhat was different about Ptolemy’s model versus Aristotle’s?What was different about Ptolemy’s model versus Aristotle’s?
A.A. The spheres were glass, not crystal The spheres were glass, not crystal
B.B. The Sun is at the center, not the Earth. The Sun is at the center, not the Earth.
C.C. He included EPICYCLES He included EPICYCLES
D.D. Some of the crystal spheres went backwards. Some of the crystal spheres went backwards.
Why wasn’t Copericus’s model immediately accepted as truth?Why wasn’t Copericus’s model immediately accepted as truth?
A.A. Don’t be silly, it was a SMASH hit! Don’t be silly, it was a SMASH hit!
B. B. It’sIt’s predictionspredictions were only as accurate as Ptolemy’s but were only as accurate as Ptolemy’s but
no better.no better.
C.C. Copernicus was just not well liked. Copernicus was just not well liked.
D.D. It’s It’s predictionspredictions were MUCH worse than Ptolemy’s. were MUCH worse than Ptolemy’s.
Johannes Johannes KeplerKepler
TheoryTheory
•A student of TychoA student of Tycho
•Studied Tycho’s dataStudied Tycho’s data
•Discovered three Discovered three empirical empirical relationshipsrelationships
•Believed CopernicusBelieved Copernicus
•Suggested that the Suggested that the Sun exerts a force on Sun exerts a force on the planets.the planets.
Kepler’s 1Kepler’s 1sstt Law Law
Orbits are ellipsesOrbits are ellipses
Kepler’s Second LawKepler’s Second Law
Planets move:Planets move:
•Fast at Fast at perihelionperihelion
•Slow at Slow at aphelionaphelion
Perihelion:Perihelion: Point in an orbit closest to the Point in an orbit closest to the Sun.Sun.Aphelion:Aphelion: Point in an orbit furthest from the Point in an orbit furthest from the Sun.Sun.
Equal areas in Equal areas in Equal timesEqual times
Kepler’s Third LawKepler’s Third Law
Orbital Period:Orbital Period:The time required to complete one orbitThe time required to complete one orbit
The harmonic law:The harmonic law: A precise mathematical relationship A precise mathematical relationship between the between the orbitalorbital periodperiod and the semi and the semi major axis.major axis.
PP2 2 = = aa33
The End of Geocentrism The End of Geocentrism … ?… ?
Mountains and SunspotsMountains and Sunspots
Moons of JupiterMoons of Jupiter
Phases of VenusPhases of Venus
The Rise of Modern The Rise of Modern PhysicsPhysics
Isaac NewtonIsaac Newton• Three laws of Three laws of
motionmotion• Universal Universal
GravitationGravitation• The CalculusThe CalculusSimple central principals Simple central principals from which all motion, from which all motion, either on Earth or in the either on Earth or in the heavens, can be derived.heavens, can be derived.