Download Copernican Revolution

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Objectives – for 2 Copernican Rev. Lectures
Describe the geocentric and the heliocentric models of the solar system.
The word planet derives from the Greek "planetes" which means wanderer. Why were the planets called wanderers?
Explain Aristotle’s main argument against the heliocentric model.
What was Aristotle’s other (and weaker) argument against the heliocentric model?
Who gave the first evidence in favor of the heliocentric model? What was the evidence?
Who added the mathematical calculations to the geocentric model?
When a planet undergoes retrograde motion, how does it look?
How did the geocentric model explain retrograde motion?
How did the heliocentric model explain retrograde motion?
What did Brahe contribute to the heliocentric vs. geocentric debate?
Define perihelion and aphelion.
Considering Kepler's three laws of planetary motion (you do not have to memorize them):
What shape orbit does a planet have?
When a satellite orbits the Earth, does it move faster at perigee or at apogee? When a comet orbits the Sun, does it
orbit faster at perihelion or at aphelion?
What is meant by the period of a planet? In our solar system, what planet has the longest period? The shortest? Which
planet orbits with the highest speed? Slowest?
What did Galileo notice about the Moon, the Sun, Jupiter, and Venus? What did he conclude from these observations?
How did the church/state react?
Why does Venus exhibit phases but Mars does not? (Hint: Draw the Sun as well as Venus, Earth and Mars in their
orbits. Shade in Venus and Mars. What do they look like from Earth’s view?)
State Newton's Universal Law of Gravity. If the mass of one of two objects increases, what happens to the
gravitational force between the objects? If the distance between the two increases, what happens to the force?
How can you tell if a process is science? (See earlier lecture on the hallmarks of science.)
When science uses the term “theory” such as the “Theory of Evolution”, is that a weak or a strong statement? What
backs up any theory in science?
Prior to the Copernican Revolution
– Greek Astronomy
• Western only – Please
investigate other cultures
• Greeks (influenced by
Babylonia, Mesopotamia,
Egypt, Rome)
• ~700 BC to ~140 AD
• Some ideas and people
• Know the starred* items
Everything orbits around…
Earth
Sun
Heliocentric Model*
Geocentric Model*
(from Aristotle, 384-322BC)
(from Copernicus, 1473-1543AD)
~700 BC Early astronomy was about time
keeping (when to sow and reap crops)
Prior to the Copernican Revolution –
Greek Astronomy
Hesiad, Works and Days
• ... when the Pleiades rise it is time to use the
sickle, but the plough when they are setting;
40 days they stay away from heaven; when
Arcturus ascends from the sea and, rising in
the evening, remain visible for the entire
night, the grapes must be pruned;…
• Needed better observations to keep the
various calendars synchronized.
Prior to the Copernican
Revolution – Greek Astronomy
Greeks ~Fifth Century BC
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What is the sun? Fire?
Tiny lights in the sky?
Why do 7 lights wander
among the others? (7 Planetes*)
science.msfc.nasa.gov/ ssl/pad/solar/surface.htm
imagine.gsfc.nasa.gov/.../ news/22apr02.html
http://artsci.shu.edu/physics/1007/retro2.gif
Prior to the Copernican Revolution –
Greek Astronomy
Pythagoras of Samos ~500 BC
• Earth is a sphere
• Sphere is perfection in math
• Crystal spheres for 7 planetes
Sun, Moon, 5 others
• Already thinking geocentric
http://library.thinkquest.org/C0126626
/fate/geocentric.jpg
Prior to the Copernican Revolution –
Greek Astronomy
Plato ~360 BC
• Heavens are perfect, unchanging
(from mathematical perfection)
• Heavenly motion must be in circles
and uniform
Prior to the Copernican Revolution –
Greek Astronomy
Aristotle ~350 BC
• Plato’s student
• Earth: Corrupt, changeable, imperfect
(separation of heavens and Earth)
• Arguments for geocentric model*
No parallax of stars*
and
Moon would be left behind*
• Parallax is the apparent change in position of an
object due to the change in position of the observer
– Parallax thumb demonstration
Prior to the Copernican Revolution
– Greek Astronomy
Aristarcus ~300 BC
• Heliocentric solar system
(first evidence)*
• Measured size of Sun*
• Measured that Sun was much
further away than Moon
Prior to the Copernican Revolution
– Greek Astronomy
Ptolemy ~140 AD
• Geocentric model* (often called the
Ptolemaic system)
• Mathematical model of universe*
– Perfect Bodies
and orbits
• circles,
spheres
– Uniform motion
– Epicycles*
(retrograde
motion)*
Prior to the Copernican Revolution
– Greek Astronomy
From Moon Lectures
Already know this:
• Minute to Minute: the Sun, Moon, stars, planets appear
to rise in East and set in West due to Earth’s spin
(rotation).
• Day to Day: Moon moves West to East due to Moon’s
orbit (revolution) around Earth.
New information:
• Day to Day: Planets typically move West to East due to
their orbits around the Sun.
• Retrograde Day to Day Motion: Planets move East to
West due to their orbits around the Sun and the
difference in speeds of Earth and other planet.
Retrograde Motion (Day to Day)
Sometimes planets moved backwards against the
background of stars.
Retrograde motion is East to West and observed day to day.
Minute to minute motion across sky is still East to West due to
Earth’s rotation.
Ptolemy
Geocentric Model
Perfect circles, spheres, uniform motion
Earth
Mars’
Epicycle
Mars
Both models explain observations…
Retrograde motion
of planets
Copernican Revolution
Retrograde motion – Geocentric
Planets ride on epicycles
Sometimes appear
to move backwards
Copernican Revolution
Retrograde motion – Heliocentric
One planet overtakes
another planet.
Slower planet appears to
move backwards.
Copernican Revolution
Retrograde motion – Heliocentric
New (and correct) explanation of retrograde motion
of the planets.
•Retrograde
(westward)
motion of a
planet
occurs when
the Earth
passes the
planet.
•Ptolemy’s
epicylces
unnecessary
Copernican Revolution
Dark Ages in Europe (5th to 15th centuries AD)
• Roman libraries sacked
• Often violent mix of Latin and Arabic
cultures
• Plague, famine, war
• Islamic Golden Age of Science
Long time between Ptolemy ~140 AD to
Copernicus ~1500 AD.
Prior to the Copernican Revolution
– Greek Astronomy
Summary
• Before Copernicus ~700BC to 140 AD
Geocentric Model Dominated
– Pythagoras of Samos
– Plato
– Aristotle*
– Aristarchus*
– Ptolemy*
Observation Projects
120+ points. Maximum cannot exceed 100 points. Projects
due by midnight on due date. (In order of due date)
X Earth-Sun Scale Model Start: Jan. 12, Due: Jan. 24 (10 pts.)
Student Success Day Jan. 31 (5 points)
Sunset – Part 1 Start: Jan. 24, Due: Feb. 14 (5 points)
Moon Phases Start: Jan. 19, Due: Mar. 2 (10 points)
Safe Sun Prep Work Start: Mar. 23, Due: Mar. 28 (10
POINTS) BRING TO SAFE SUN OBSERVATION
Sunset – Part 2 Start: Mar. 28, Due: Apr. 25 (10 points)
Planetarium Start: Feb. 14, Due: May 4 (10 points)
Star Gazing Start: Jan. 17, Due: May 4 (25 points)
Telescope Start: Jan. 17, Due: May 4 (25 points)
Moon Craters Start: Jan. 17, Due: May 4 (10 points)
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Homework
No Lecture Tuesday Jan. 31 (due to Student Success Day)
No Lab next week (due to Student Success Day)
D2L Quizzes 4 available – quiz 3 on Cycles of the Sky (Moon); quiz 4
on Copernican Revolution (today and in 1 week)
Test 1 on Feb. 7
• Best test prep: 1. objectives, 2. D2L quizzes, 3. lectures/notes,
4. textbook (50-60 multiple choice questions, some from quizzes)
Sunset Part 1, Due Feb. 14
• Sunset times:
• https://www.timeanddate.com/sun/usa/minneapolis
• Phone App: Sunrise Sunset or Weather App
Moon Phases, Due Mar. 2
• Moon visible times: (Moonrise and Moonset)
• http://www.timeanddate.com/moon/usa/minneapolis
• Phone App: Phases of the Moon Free
Grades are updated weekly, usually Wednesdays on website
Keep up with objectives (flashcards) and reading the text