2 Extra Credit 1. Sat. Sept. Mt. Tam, Marin. Dr. Jill Tartar will give a talk on: Searching for Aliens, Finding Ourselves 2. SF State Observatory Open Mon, Wed & Thurs at 7:15 PM 3. Observe the Moon yourself starting tonight!
3 In Class Voting Sheet Print out from: physics.sfsu.edu/~chris/astro115 A B Bring your voting sheet to EVERY class. Its mandatory... and fun! C D
4 Test Question: What s your favorite class? A. Astronomy B. Astronomy C. Astronomy D. Astronomy
5 Question: Over the course of a year, how does the Sun s position appear to change? A. The sun appears in front of every one of the constellations B. The sun appears in front of just 13 of the constellations C. The sun appears to tilt D. The sun appears to shrink significantly.
6 The Moon is rising in this photo. What time of day is it? A. Sunrise B. Sunset C. Noon D. Midnight
7 This photo was taken just before Sunrise. The Moon is on the EASTERN Horizon. What phase is the Moon in? A. Full Moon B. First Quarter C. Crescent D. Gibbous
8 Chapter 2 The Motion of the Planets!What paths do the planets take through space?!why do they follow these paths?!the human quest to answer these questions led to the birth of modern science
9 Science & Theories Science does not provide absolute truth ; it is not always right. But it is very reliable. How reliable is a Scientific theory? Would you bet your life on a theory? Too late...you already have...and wisely. (eg. Aerodynamics tells us how airplanes work; Electromagnetism allows us to build traffic lights) A theory has been tested over and over & always passed the test. Nevertheless, theories that have been used for many years are sometimes refined or abandoned if disproven. So, science is self-correcting. How did humans develop this reliable way to understand the world?
10 Planets: Wanderers in The Sky! Ancient peoples noticed that five stars seemed to move...! They called them Planets which means wanderers.! Every ancient civilization was aware of these 5 planets.! Words for the days of the week derive from the 5 visible planets: Mercury, Venus, Mars, Jupiter, and Saturn.
11 How Planets Move! In one night, the planets move from East to West due to Earth s rotation.! But, Night after night, planets drift slowly from West to East with respect to the background stars.! This is called direct motion.! However sometimes a planet reverses direction!! We call this backward drift retrograde motion. ast West
14 Ptolemy s Geocentric Model! Greek scientist Ptolemy worked at the Great Library of Alexandria in Egypt (~140 AD)! His research included astronomy, astrology, geography & music.! Ptolemy used a geocentric model of the solar system explain retrograde motion.! Earth was at the center.! In Ptolemy s model, the planets travel along small circles (epicycles) that move on larger circles.
15 Ptolemy s Geocentric model
16 Geocentric Model Planets Circle the Earth on epicycles anim.
17 The Geocentric Model! Ptolemy s views were published in a book: the Almagest! Because it could explain retrograde motion, his theory was widely accepted by European & Middle Eastern astronomers.! When later observations did not agree with the Geocentric Model, many small changes were added.! The Model became quite cumbersome, but it was widely accepted for 1,600 years!
18 How do you Challenge an accepted theory?! Arab scientist Alhazan* ( ) came up with a way.! Like Ptolemy, he lived in Egypt and studied many subjects (optics, astronomy, math, geometry)! A hypothesis must be proved by experiments that can be confirmed, he said.! Later scientists in Europe read his books, and developed what we now call the scientific method. *a.k.a. Ibn al-haytham
19 Copernicus Heliocentric theory! We credit Nicolaus Copernicus, a 16th-century Polish astronomer, with our modern view of the Solar System! Copernicus suggested a heliocentric theory! Sun was at the center of the Solar System.! Planets moved in circles around the Sun. Copernicus could also explain retrograde motion.
20 I began to be annoyed that the movements of the world machine were not understood with greater certainty by the philosophers, who otherwise examined so precisely the most insignificant trifles of the world. Copernicus, Book on the Revolutions, 1543
21 it is just like someone taking from various places hands, feet, a head, and other pieces, each very well depicted, but not for the representation of a single person. In forcing these fragments together, they created a monster rather than a man. Copernicus, Book on the Revolutions, 1543
22 An inner planet (eg. Earth) catches up with an outer planet (eg. Mars) causing it to appear to move backward (retrograde motion)
23 Copernicus Heliocentric Theory! Copernicus new theory clearly stated planets positions relative to the Sun! It predicted the next appearances of planets in the sky.! These predictions proved correct, lending support to Copernicus Heliocentric Model.! However, his model was no more accurate than the Geocentric model
24 A Heretical Idea?! Copernicus Heliocentric theory caused problems with the Church.! The Church had accepted Ptolemy s geocentric universe.! It agreed with the Church s notion of heaven as a perfect place.! To question this model was to question the Church s authority.! Copernicus book was censored by the Catholic Church.! Copernicus died before the full effects of his model were felt! However, other astronomers supported his model, using their observations.
25 Galileo Galileo Galilei ( ) was an Italian scientist who studied many fields. He tried to measure the speed of light, and studied gravity. He obtained the first observations to confirm the Heliocentric Model
26 More Evidence for the Copernican Model! Galileo was the first person to use a telescope for astronomy.! Several of his observations supported the Heliocentric model of Copernicus:! He discovered moons orbiting Jupiter (not the Earth)
28 Galileo Galilei! Galileo observed Venus with his telescope.! He reported seeing crescent and gibbous phases on Venus! Gibbous phases are only possible if Venus is on the other side of the Sun from us.! This can t happen in the Geocentric model of the Universe!
29 Geocentric model Of Ptolemy
30 Theory: Venus is always between the Sun and Earth Prediction: Venus will always be seen in crescent phase
31 Not to scale! Theory: Venus sometimes goes behind the Sun Prediction: Venus will sometimes be seen in gibbous phase. Telescope Observation: Venus does show gibbous phase!
32 Galileo Challenges the Geocentric Model! Heliocentric model challenged beliefs held for 2000 years.! The Church felt threatened by this.! Galileo was arrested and tried.! He had reason to fear: Giordano Bruno, another advocate of the Heliocentric Model, was tried by The Inquisition.! Bruno was burned at the stake for heresy!! Galileo was not allowed to advocate the Heliocentric Model.! However word of his discoveries spread.
33 Tycho Brahe! Tycho Brahe ( ) was a Danish nobleman! As a child, he had witnessed a Solar Eclipse! He was so impressed that eclipses could be predicted, that he dedicated his life to astronomy.! He built his own observatory on an island.! He observed a nova or new star, and found it was outside the solar system.
34 Tycho Brahe! Tycho made the most precise observations of the planets to date without using a telescope.! During his life, Tycho was reluctant to share his precise data.! He also had a wild lifestyle, and lost his nose in a duel.! He attended many royal parties! Perhaps one too many. He died after eating and drinking too much at a party.
35 Johannes Kepler! After Tycho died, his assistant, Johannes Kepler, took his place.! Unlike others, Kepler saw planets as real objects, which required a physical theory.! (He even wrote the first Sci-Fi novel, Somnium, about space travel) Kepler studied Tycho s precise observations of the planets! He saw patterns in their motion never seen before.
36 Platonic Solids Initially, Kepler thought the orbits of the planets had the same proportions as the 5 Perfect Solids of geometry. He studied this for years, but could not support it with observations.
37 Kepler! However, Kepler did not give up.! His next model matched 10 of Tycho s observations of Mars perfectly.!...but it mis-matched 2 of Tycho s observations... by only 0.1 degree.! So, he rejected that idea also.! He found that the planets motions could be explained if he gave up the idea of circular orbits.! In time he discovered that all planets follow the same three rules..! Kepler s Laws of Planetary Motion
39 Ellipse Shapes Circle
40 How to draw an Ellipse Ellipse Kit
41 Size of an Ellipse! An ellipse is a flattened circle.! We measure the size of a circle using: Diameter or Radius! But how would you measure the size of an ellipse?! It has two diameters :! The major axis of an ellipse is its long diameter! (The major axis passes through the two foci.)! The minor axis is perpendicular to the major axis.
43 Kepler s Second Law! When a planet is at its greatest distance from the Sun it moves the slowest! When a planet is at its smallest distance from the Sun it moves the fastest.! The point of closest approach to the Sun is called perihelion! The point of farthest distance from the Sun is called aphelion
44 Kepler s 3 rd Law... relates a planet s Orbit Period to its Semimajor axis Orbital Period (P) = time it takes to orbit the Sun once (in years) Semi-major axis (a) = distance from the planet to the Sun (in AU) The Astronomical Unit (AU) is a unit of distance a It is used to measure distances to planets. 1 AU = Earth s distance from the Sun = 93,000,000 miles
45 Kepler was the first to realize that P is related to a...in the same way for every planet. Kepler s 3 rd Law P 2 = a 3 P = orbital period in years a = semi-major axis in A.U. P A P 2 A 3
46 Kepler s Third Law An Example The Planet Uranus orbits the Sun at a distance of 19 AU. So its semimajor axis is: a= 19 AU Question: How long does it take Uranus to Orbit the Sun? P 2 =a 3 a 3 = a x a x a = 19 x 19 x 19 = 6859 P 2 = a 3 = 6859, so P = the square root of 6859 = 83 years
47 Kepler s Third Law An Example The Planet Saturn orbits the Sun in 29 years Question: How far is Saturn from Sun? P 2 =a 3 P 2 = 29 x 29 = 841. So a 3 = 841 What is a? a 3 = a x a x a Take a guess: a=10. Then a x a x a = 1000 too high Guess: a=9. Then a x a x a = 729 too low Answer: a= 9.5
Kepler s Laws Learning Objectives! Do the planets move east or west over the course of one night? Over the course of several nights? How do true motion and retrograde motion differ?! What are geocentric
Name: Date: 1. The word planet is derived from a Greek term meaning A) bright nighttime object. B) astrological sign. C) wanderer. D) nontwinkling star. 2. The planets that were known before the telescope
Lecture 4: Kepler and Galileo Astronomy 111 Wednesday September 6, 2017 Reminders Online homework #2 due Monday at 3pm Johannes Kepler (1571-1630): German Was Tycho s assistant Used Tycho s data to discover
ASTR 111 003 Fall 2006 Lecture 03 Sep. 18, 2006 Introduction To Modern Astronomy II Introducing Astronomy (chap. 1-6) Planets and Moons (chap. 7-17) Ch1: Astronomy and the Universe Ch2: Knowing the Heavens
Gravitation Part I. Ptolemy, Copernicus, Galileo, and Kepler Celestial motions The stars: Uniform daily motion about the celestial poles (rising and setting). The Sun: Daily motion around the celestial
Lecture #5: Plan The Beginnings of Modern Astronomy Kepler s Laws Galileo Geocentric ( Ptolemaic ) Model Retrograde Motion: Apparent backward (= East-to-West) motion of a planet with respect to stars Ptolemy
The Scientific Revolution What is a Revolution? A Revolution is a complete change, or an overthrow of a government, a social system, etc. The Scientific Revolution In the 1500s and 1600s the Scientific
Directions: Read each slide and decide what information is needed. Some slides may have red or yellow or orange underlined. This information is a clue for you to read more carefully or copy the information
ASTR 111 003 Fall 2006 Lecture 03 Sep. 18, 2006 Introduction To Modern Astronomy I Introducing Astronomy (chap. 1-6) Planets and Moons (chap. 7-17) Ch1: Astronomy and the Universe Ch2: Knowing the Heavens
Cosmogony A cosmogony is theory about ones place in the universe. A geocentric cosmogony is a theory that proposes Earth to be at the center of the universe. A heliocentric cosmogony is a theory that proposes
Models of the Solar System The Development of Understanding from Ancient Greece to Isaac Newton Aristotle (384 BC 322 BC) Third in line of Greek thinkers: Socrates was the teacher of Plato, Plato was the
Planetary Orbits: Kepler s Laws Announcements The correct link for the course webpage http://www.lpl.arizona.edu/undergrad/classes/spring2007/giacalone_206-2 The first homework due Jan 25 (available for
CW10 p374 Vocab What is a Revolution? A Revolution is a complete change, or an overthrow of a government, a social system, etc. The Scientific Revolution In the 1500s and 1600s the Scientific Revolution
Things to do today After this lecture, please pick up: Review questions for the final exam Homework#6 (due next Tuesday) No class on Thursday (Thanksgiving) Final exam on December 2 (next Thursday) Terminal,
Astronomy- The Original Science Imagine that it is 5,000 years ago. Clocks and modern calendars have not been invented. How would you tell time or know what day it is? One way to tell the time is to study
http://radicalart.info/physics/vacuum/index.html The Scientific Revolution In the 1500s and 1600s the Scientific Revolution changed the way Europeans looked at the world. People began to make conclusions
Earth Science, 13e Tarbuck & Lutgens Origins of Modern Astronomy Earth Science, 13e Chapter 21 Stanley C. Hatfield Southwestern Illinois College Early history of astronomy Ancient Greeks Used philosophical
The Puzzle of Planetary Motion versus Finding Earth s place in the Universe Observing the Planets Five of the planets are bright enough to be seen by the unaided eye. This view shows the sky after sunset
PHYS 160 Astronomy Test #1 Fall 2017 Version B 1 I. True/False (1 point each) Circle the T if the statement is true, or F if the statement is false on your answer sheet. 1. An object has the same weight,
In so many and such important ways, then, do the planets bear witness to the earth's mobility Nicholas Copernicus What We Will Learn Today What did it take to revise an age old belief? What is the Copernican
Astronomy 1 Fall 2016 Comet Halley Edmund Halley, a friend of Newton s used Newton s math to predict the return of a comet seen at intervals of 76 years. Lecture 3; September 29, 2016 Previously on Astro-1
The Scientific Revolution Consider the following. Put them in order from most true to least true. 1. That house is on fire. 2. God exists. 3. The earth moves around the sun. 4. 2 + 2 = 4 5. Michelangelo
Claudius Ptolemaeus Second Century AD Jan 5 7:37 AM Copernicus: The Foundation Nicholas Copernicus (Polish, 1473 1543): Proposed the first modern heliocentric model, motivated by inaccuracies of the Ptolemaic
Early Models of the Universe How we explained those big shiny lights in the sky The Greek philosopher Aristotle (384 322 BCE) believed that the Earth was the center of our universe, and everything rotated
Chapter 2 The Rise of Astronomy Copyright (c) The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Periods of Western Astronomy Western astronomy divides into 4 periods Prehistoric
This Class (Lecture 32): Cultural Evolution Next Class: Lifetime ET: Astronomy 230 HW 7 due today! Outline Will a civilization develop that has the appropriate technology and worldview? The most important
Observing Project Remember that for one of your observing projects you can go to a star party (stargazing). This is available at the Lawrence Hall of Science every 1st and 3rd Saturday of the month. For
The History of Astronomy Theories, People, and Discoveries of the Past Early man recorded very little history. Left some clues in the form of petrographs. Stone drawings that show eclipses, comets, supernovae.
A more in depth explanation from last week: If Earth had no tilt, what else would happen? The equator would be much hotter due to the direct sunlight which would lead to a lower survival rate and little
Understanding Planetary Motion Use experimental observations (made prior to telescopes) to understand motion of the planets. Period is easy, distances and orbit shape are hard (except Venus and Mercury
Motions of the Planets ASTR 2110 Sarazin Motion of Planets Retrograde Motion Inferior Planets: Mercury, Venus Always near Sun on Sky Retrograde motion when very close to Sun on sky (Every other time) Superior
Lecture 3: History of Astronomy Astronomy 111 Monday September 4, 2017 Reminders Labs start this week Homework #2 assigned today Astronomy of the ancients Many ancient cultures took note of celestial objects
Astronomy 230 Section 1 MWF 1400-1450 106 B6 Eng Hall This Class (Lecture 20): Evolution of the Worldview Next Class: Lifetime Presentations MWF: Arthur Jones Mark Piergies Matt Clarkin Gergana Slavova
A100 Exploring the Universe: The Rise of Science Martin D. Weinberg UMass Astronomy email@example.com September 11, 2012 Read: Chap 3 09/11/12 slide 1 Problem Set #1 due this afternoon at 5pm! Read:
Practice Test DeAnza College Astronomy 04 Test 1 Spring Quarter 2009 Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. Mark answer on Scantron.
2006 Pearson Prentice Hall Lecture Outlines PowerPoint Chapter 21 Earth Science 11e Tarbuck/Lutgens This work is protected by United States copyright laws and is provided solely for the use of instructors
Chapter 1 The Copernican Revolution The Horse Head nebula in the Orion constellation (Reading assignment: Chapter 1) Learning Outcomes How the geocentric model accounts for the retrograde motion of planets?
Astro 210 Lecture 6 Jan 29, 2018 Announcements HW2 due online in PDF, Friday 5:00 pm HW1 extended until 11:59pm today register your iclicker; link on course webpage first Planetarium shows Mon Feb 5 and
Exam #1 Study Guide (Note this is not all the information you need to know for the test, these are just SOME of the main points) Moon Phases Moon is always ½ illuminated by the Sun, and the sunlit side
~1500 to ~1700 Copernicus (~1500) Brahe (~1570) Kepler (~1600) Galileo (~1600) Newton (~1670) The Issue: Geocentric or Heliocentric Which model explains observations the best? Copernicus (~1500) Resurrected
1 How Astronomers Learnt that The Heavens Are Not Perfect Introduction In this packet, you will read about the discoveries and theories which changed the way astronomers understood the Universe. I have
Was Ptolemy Pstupid? Why such a silly title for today s lecture? Sometimes we tend to think that ancient astronomical ideas were stupid because today we know that they were wrong. But, while their models
A100 Exploring the Universe: The Invention of Science Martin D. Weinberg UMass Astronomy firstname.lastname@example.org September 09, 2014 Read: Chap 3 09/09/14 slide 1 Problem Set #1: due this afternoon
In ancient times phenomena in the sky were not understood! Chapter 2 The Science of Life in the Universe The Ancient Greeks The Scientific Method Our ideas must always be consistent with our observations!
Plato (428-348 BC) All natural motion is circular Reason is more important than observation Aristotle (384-322 BC) Physics elements earth water air fire quintessence Eratosthenes (276-195 BC) He measured
Chapter 4 The Origin Of Modern Astronomy Slide 14 Slide 15 14 15 Is Change Good or Bad? Do you like Homer to look like Homer or with hair? Does it bother you when your schedule is changed? Is it okay to
ASTR-1010: Astronomy I Course Notes Section III Dr. Donald G. Luttermoser Department of Physics and Astronomy East Tennessee State University Edition 2.0 Abstract These class notes are designed for use
1. So far as we know, the first person who claimed that natural phenomena could be described by mathematics was A) Copernicus. B) Pythagoras. C) Aristotle. D) Ptolemy. 2. The groundwork for modern science
Position 3 None - it is always above the horizon. N E W S Agree with student 2; star B never crosses horizon plane, so it can t rise or set. Imaginary plane No; the Earth blocks the view. Star A at position
Descriptive Astronomy (ASTR 108) Exam 1 B February 17, 2010 Name: In each of the following multiple choice questions, select the best possible answer. In the line on the scan sheet corresponding to the
Descriptive Astronomy (ASTR 108) Exam 1 A February 17, 2010 Name: In each of the following multiple choice questions, select the best possible answer. In the line on the scan sheet corresponding to the
Astronomy 1010 Planetary Astronomy Sample Questions for Exam 1 Chapter 1 1. A scientific hypothesis is a) a wild, baseless guess about how something works. b) a collection of ideas that seems to explain
Greek Astronomy Aristotelian Cosmology: Evidence that the Earth does not move: 1. Stars do not exhibit parallax: 2-1 At the center of the universe is the Earth: Changeable and imperfect. Above the Earth
Planets in the Sky ASTR 101 2/16/2018 1 Planets in the Sky 2018 paths of Jupiter among stars (2017/2018) Unlike stars which have fixed positions in the sky (celestial sphere), planets seem to move with
EXAM #2. ANSWERS ASTR 1101-001, Spring 2008 1. In Copernicus s heliocentric model of the universe, which of the following astronomical objects was placed in an orbit around the Earth? The Moon 2. In his
FAMILY NAME : (Please PRINT!) GIVEN NAME : (Please PRINT!) Signature: ASTRONOMY 4 DeAnza College Winter 2018 First Midterm Exam MAKE ALL MARKS DARK AND COMPLETE. Instructions: 1. On your Parscore sheet
8 Astronomers.notebook Astronomy Lesson 8.1 Astronomy s Movers and Shakers Aristotle 384 322 BCE Heavenly objects must move on circular paths at constant speeds. Earth is motionless at the center of the
The Birth of Astronomy Lecture 3 1/24/2018 Fundamental Questions of Astronomy (life?) What is the shape of the Earth? How big is the planet we live on? Why do the stars move across the sky? Where is Earth
Astronomy A BEGINNER S GUIDE TO THE UNIVERSE EIGHTH EDITION CHAPTER 1 The Copernican Revolution Lecture Presentation 1.0 Have you ever wondered about? Where are the stars during the day? What is the near
Chapter 2 The Rise of Astronomy Copyright (c) The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2.1: Early Ideas of the Heavens: Classical Astronomy As far as we know, the
8.1 notes.notebook Claudius Ptolemaeus Second Century AD Jan 5 7:7 AM Copernicus: The Foundation Nicholas Copernicus (Polish, 147 154): Proposed the first modern heliocentric model, motivated by inaccuracies
SCIENTIFIC REVOLUTION VOCABULARY: SCIENTIFIC REVOLUTION Revolution a sweeping change Geocentric earth-centered universe Astronomer scientist who studies the motion of stars and planets Heliocentric sun-centered
Chapter 3 The Science of Astronomy 3.1 The Ancient Roots of Science Our goals for learning: In what ways do all humans employ scientific thinking? How did astronomical observations benefit ancient societies?
This Class (Lecture 30): Evolution of the World View Next Class: Lifetime Astronomy 230 Section 1 MWF 1400-1450 106 B1 Eng Hall Presentations on Nov 10 th! Brad Rockwell Sean Boyer Patrick Sawica Outline
1. The possibility of extraterrestrial life was first considered A) after the invention of the telescope B) only during the past few decades C) many thousands of years ago during ancient times D) at the
Chapter 02 The Rise of Astronomy Multiple Choice Questions 1. The moon appears larger when it rises than when it is high in the sky because A. You are closer to it when it rises (angular-size relation).
Ch 22 Origin of Modern Astronomy Notes Ch 22.1 Early Astronomers Astronomy: The science that studies the universe, dealing with properties of objects in space. Astrology: A belief that the positions of
Announcements Results of clicker questions from Monday are on ICON. First homework is graded on ICON. Next homework due one minute before midnight on Tuesday, September 6. Labs start this week. All lab
2X CLAUDIUS PTOLEMY BIOGRAPHY 1260L CLAUDIUS PTOLEMY AN EARTH-CENTERED VIEW OF THE UNIVERSE Born 85 CE Hermiou, Egypt Died 165 CE Alexandria, Egypt By Cynthia Stokes Brown The Earth was the center of the
Chapter Origin of Modern Astronomy 22.1 Early Astronomy Ancient Greeks Astronomy is the science that studies the universe. It includes the observation and interpretation of celestial bodies and phenomena.
Lecture #4: Plan Early Ideas of the Heavens (cont d): Shape & size of the Earth Size & distance of Moon & Sun Geocentric Universe Heliocentric Universe Shape of the Earth Aristotle (Greece, 384 322 B.C.)
Gravitation and the Motion of the Planets 1 Guiding Questions 1. How did ancient astronomers explain the motions of the planets? 2. Why did Copernicus think that the Earth and the other planets go around
Kepler s laws Astronomy 101 Syracuse University, Fall 2018 Walter Freeman October 2, 2018 Astronomy 101 Kepler s laws October 2, 2018 1 / 23 And yet it moves. Galileo (attributed), on the Earth Astronomy
Copernican Revolution 15 Jan Final exam is Wed, May 6 th, not 5 th. Questions on reading Motion of the sun & planets Ptolemy s Almagest Copernicus de Revolutionibus Orbium Caelestium, (Concerning Revolutions
Multiple Choice: Select the choice that best answers each question. Write your choice in the blank next to each number. (2 points each) 1. At the North Pole in mid-november, the sun rises at a. North of
Physics Unit 7: Circular Motion, Universal Gravitation, and Satellite Orbits Planetary Motion Geocentric Models --Many people prior to the 1500 s viewed the! Earth and the solar system using a! geocentric
PHYS 1411 Introduction to Astronomy History of Astronomy Chapter 4 Renaissance Period Copernicus new (and correct) explanation for retrograde motion of the planets Copernicus new (and correct) explanation
Models of the Solar System, Gravitation and the motion of the Planets A.K.A DEAD WHITE GUYS WEEK! 1/28/14 Cosmogony A cosmogony is theory about ones place in the universe. A geocentric cosmogony is a theory