Transcript Copernican Revolution - Welcome to MCTCteach

Today’s Comments
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Grades are updated on class website.
D2L 4 quizzes available to practice for test
Test update – about 60 multiple choice Tuesday, Feb. 10
• Bring pencil (required) & simple calculator (optional, not
necessary for simple division/multiplication)
• Study Session with Gus (tutor) Thursday, Feb. 5, 3-5pm
Room S3300 (Today!)
• Best test prep: 1. objectives (updated on web),
2. D2L quizzes, 3. lectures/notes, 4. book
Observations – Sunset Part 1 due in 1 week (Feb. 12)
Make sure to save your Sunset Part 1 picture so you can use
it for Part 2 in April.
Copernican Revolution
~1500 to ~1700
People Who Contributed*
Copernicus (~1500)
Brahe
(~1570)
Kepler
(~1600)
Galileo
(~1600)
Newton
(~1670)
Copernican Revolution
Copernicus (~1500)
Resurrected heliocentric model*
First suggested by Aristarchus*
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Is solar system geocentric or heliocentric?*
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Both models have:
Circular orbits (heavenly perfection)
Uniform motion (heavens cannot change)
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Both models explain observations…
Sun, Moon, Planets
Rise in east, Set in west
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Both models explain observations…
Retrograde motion
of planets
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Retrograde motion – Geocentric
Planets ride on epicycles
Sometimes appear
to move backwards
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Retrograde motion – Heliocentric
One planet overtakes
another planet.
Slower planet appears to
move backwards.
Copernican Revolution
Copernicus (~1500)
Brahe
(~1570)
Kepler
(~1600)
Galileo
(~1600)
Newton
(~1670)
Copernican Revolution
Brahe (~1570)
Built excellent instruments.*
Collected 20+ years of data from
observations.*
Measured position of Mars very accurately.*
Stayed with geocentric model.*
Saw a supernova! (the sky changed)
Copernican Revolution
Copernicus (~1500)
Brahe
(~1570)
Kepler
(~1600)
Galileo
(~1600)
Newton
(~1670)
Copernican Revolution
Kepler (~1600)
Derived (from Brahe’s data)
Three mathematical laws
of planetary motion.
Copernican Revolution
Kepler’s First Law
1. Planets have elliptical orbits around the Sun*
<
aphelion
perihelion
>
Copernican Revolution
Kepler’s Second Law
2. The radius vector sweeps out equal areas in equal times.
<
>
Thirty
days
Thirty
days
Radius
vector
>
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Kepler’s Second Law means that…
A planet changes speed*;
faster at perihelion, slower at aphelion
Perihelion
(faster)
Aphelion
(slower)
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Definition needed for
Kepler’s Third Law
Period = Time to complete one cycle
Ex: Earth’s period of rotation =?
Ex: Earth’s period of revolution = ?
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Kepler’s Third Law
3. Period2 is proportional to (Radius of orbit)3
• Sometimes written as P2 α r3
• Bigger orbit radius means longer to revolve
• More distant planet takes more time to revolve.*
• More distant planet moves slower.*
Copernican Revolution
Kepler’s 3 Laws
1.
2.
Planets have elliptical orbits around the Sun*
The radius vector sweeps out equal areas in
equal times.
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3.
A planet changes speed*
Period2 is proportional to (Radius of orbit)3
•
More distant planet takes more time to revolve.*
Copernican Revolution
Kepler’s Laws
Also applies to objects in orbit around a central mass
•Satellites around Earth
•Star around a black hole
•Planets around other stars
•Two stars orbiting each other
Copernican Revolution
Copernicus (~1500)
Brahe
(~1570)
Kepler
(~1600)
Galileo
(~1600)
Newton
(~1670)
Copernican Revolution
Meanwhile…
Out in the streets…
Galileo (~1600)
Developed and used the telescope
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Galileo observed…
1. Moon craters*
Heavens are not perfect*
!!!Heavens are Earth-like!!!*
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Cigoli – 1622
El Greco < 1600
Painted
imperfect
cratered Moon
Painted imperfect heavens
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Art and ideas flourished*
Frontpiece of G.B.
Riccioli's
Almagestum
Novum, 1651.
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Important astronomy
reference book
Image includes
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Models (Copernicus,
Riccioli, Ptolemy)
Riccioli’s model has
Jupiter and Saturn
centered on Earth
Solar scope.
Top of the Riccioli’s famous image
(from previous slide)
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Planets around the Sun
Galileo observes…
1. Moon Craters*
Heaven is
not perfect!!*
2. Sunspots*  Sun Rotates
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3. Galileo observes…
4 Moons
of Jupiter*
Earth is
not the
ONLY
center of
motion in
the
heavens
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3. Galileo observes…
4 Moons
of Jupiter*
AND
Take that, Aristotle!
Hey, Aristotle.
Earth can move
and pull the
Moon along.
Copernican Revolution
4. Galileo Observes Phases of Venus*
• Geocentric model predicts:
• Crescent phase only and little size change
• Heliocentric predicts:
• All phases AND
• Gibbous is small, while crescent is large
Play Venus phases video
http://galileoandeinstein.physics.virginia.edu/more_stuff/flashlets/PhasesofVenus.htm
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4. Galileo Observes Phases of Venus*
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http://astronomy.nmsu.edu/geas/lectures/lecture11/slide02.html
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Galileo Observed*
1. Imperfect heavens, like Earth*
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Moon craters*
2. Sunspots*
3. Jupiter’s moons*
4. Phases of Venus*
Copernican Revolution
Copernicus (~1500)
Brahe
(~1570)
Kepler
(~1600)
Galileo
(~1600)
Newton
(~1670)
Copernican Revolution
Newton (~1700)
HOW planets orbit
(and objects move)
Same laws apply to terrestrial (Earth) objects
and celestial objects*
o called the Newtonian synthesis
o Means Earth and heavens are alike*
Copernican Revolution
Newton (~1700)
HOW planets orbit
(and objects move)
Newton’s Cannon Demo
http://spaceplace.nasa.gov/how-orbits-work/en/
• Objects in orbit are continuously falling*
• Floating in space is really falling (not due to zero gravity)
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Newton (~1700)
Three Laws of Motion
(Read but not on test)
And
The Universal Law of Gravity*
Copernican Revolution
Newton - Universal Gravity*
Every mass exerts a force on every other mass.
Note the UNIVERSAL statement.
F
m1
F
m2
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Newton - Universal Gravity
F
m1
F
m2
Gravity always attracts*
Bigger mass means bigger force*
Bigger separation means smaller force*
Copernican Revolution
Newton - Universal Gravity
F
m
F
M
D
F  G
mM
D
2
Copernican Revolution
Newton - Universal Gravity
Side comments:
Predictability, Mechanistic universe
F
m1
F
m2
D
F  G
mM
D
2
Copernican Revolution
Copernican Revolution
Newton - Universal Gravity
Side comments:
Predictability, Mechanistic universe
Chaos theory
F
Why gravity?
m1
F
m2
D
F  G
mM
D
2
Copernican Revolution
Copernican Revolution - Summary
Geocentric Vs. Heliocentric
Five people, contributions, significance
Copernicus
Brahe
Kepler
Galileo
Newton
(~1500)
(~1570)
(~1600)
(~1600)
(~1670)
Process of science
Copernican Revolution
Science
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Science - A process of knowing that
uncovers the laws and processes of the
universe*
Differs from theology or philosophy
 Way to get passed the conflicts in various
belief systems (by looking at evidence)
 Sagan: “It doesn’t matter if it makes you feel
good. What matters is, is it true?”
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Process of Science*
(scientific method)
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Observe
Question
Model (hypothesize)
Predict
Test
Revise
You use much of this process all the time
in daily life
 Examples: Car stops….
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Flashlight doesn’t work…
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Cooking…
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Three Hallmarks of Science*
(How science stands apart.
More on this here: Bennett - Cosmic Perspective)
Natural explanations (not supernatural)
 Models that make testable predictions
 Simplest explanation; K.I.S.S. (Occam’s
Razor)
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Theory vs. Law
Vote: Which is stronger? Or more
powerful?
 Theory !!!!!!
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“Oh it’s just a theory.”
 It is not just a theory. It is more powerful
than a law.
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Law
Explains what happens*
 Predicts what will happen in specific cases
 Ex - Universal Law of Gravity
If you drop a rock, it will fall down (and
what force is exerted on it)
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Theory
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Explains why things happen*
Includes laws
Allows predictions of new tests of itself
Ex - General Theory of Relativity
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Explains WHY gravity works
Includes the Law of Gravity AND more
Explains the precession of Mercury’s perihelion
Predicts the existence of Black Holes
Theory
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Explains why things happen*
Includes laws
Allows predictions of new tests of itself
Supported by many scientists
Supported by many testable predictions
Can never can be proven but has not been
disproven
Can always be modified, based on new
data/information*
Exercise
Can you investigate this using science?
 If so, does science support the idea?
 If not, why not? (what hallmarks?)
Ex –
People get nuttier during a full Moon.
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Exercise
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Can you investigate these using science?
If so, does science support the idea?
If not, why not?
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A car can skid on ice.
Your personality is determined by the position of the
Sun, Moon, and Planets when you were born.
The universe and its contents evolve.
God exists.
Intelligent Design is science.