1 The History of Astronomy Theories, People, and Discoveries of the Past
2 Early man recorded very little history. Left some clues in the form of petrographs. Stone drawings that show eclipses, comets, supernovae. The petrograph to the right represents a supernova. Found in a pueblo in southwest America. Prehistory
3 Prehistory Early man was frightened by the sky. Believed that the heavens held power over earthly existence. Psychology of the Unknown Astrology born as an attempt to understand, predict, and influence events.
4 History First written records were astronomical observations. Early Chinese, Central American (Mayans), and Northern Europe. Stonehenge in England marks solstices.
5 1600 B.C. Babylonians First to write stuff down. This early culture recorded the positions of the planets, the times of eclipses, and other celestial phenomena.
6 ~500 B.C. Hellenistic Culture Greeks acquired the records of the Babylonians. Conquest of Alexander the Great. Greeks applied data to construct a cosmological framework. Basically means this is the way heaven is arranged.
7 ~500 B.C. The Greeks used the star charts for more than just practical uses. Navigation on the seas. Began to develop new ideas about the universe. Devised new experiments to try to prove their theories.
8 ~ 480 B.C. Thales of Miletus Proposed that the universe was rational and could be understood by humans. Used the data of the Babylonians to predict the occurrence of eclipses.
9 400 B.C. Plato Made what seems like a minor contribution. But his statement dominated astronomical thinking for centuries. Heaven is perfect and a circle is the perfect form.
10 330 B.C. Heraclides Proposed the first model of the solar system. Geocentric Earth at the center of the universe.
11 330 B.C. Orbits were perfect circles (Plato). Was the first round in the debate over geocentric vs. heliocentric solar system.
12 270 B.C. Round 2 Aristarchus of Samos Made several important contributions. He was the first person to propose a heliocentric model of the solar system. Mathematically proved the Sun is farther away from the Earth than the Moon.
13 270 B.C. This model put the Sun at the center (helios is Greek for Sun, thus heliocentric model). Still used circles for the orbits (Plato).
14 270 B.C. Used trigonometry to prove that the Sun is farther away from the Earth than the Moon. Idea was correct, just made mathematical errors.
15 270 B.C. Parallax Problems with Aristarchus model: 1. If the Earth is moving, why couldn t people feel it? 2. No parallax seen in the stars. a. As Earth moves in orbit, the apparent position of nearby stars move in relation to stars farther away. 3. Geocentric = Egocentric a. More natural. b. Highlights importance of man!
16 100 B.C. Hipparchus Produced the first star catalog showing positions and magnitude (brightness). Recorded names of constellations.
17 200 A.D. Ptolemy Librarian in the ancient city of Alexandria. Resurrected Heraclides geocentric model. Used the library resources containing centuries of data to formulate a complete description of the solar system.
18 200 A.D. Ptolemy explained and predicted the apparent motions of celestial bodies (planets). He used perfect circular orbits for the planets, drawing on Plato s idea that all things in heaven were perfect. Major problem was retrograde motion.
19 Retrograde Motion Retrograde motion is movement in the opposite direction from the expected motion. Some planets would move backwards during their motion across the nighttime sky over the year. This became very difficult to explain in a geocentric model because the orbits were supposed to be perfect circles around the Earth. Epicycle Motion
20 Ptolemaic Model Ptolemy developed a very complex system using circles to explain the retrograde motion of the planets. He used circles on circles as seen below. The Sun and Moon did not need them because they did not exhibit retrograde motion.
21 Ptolemaic Model The main circle around the Earth was called a deferent. The smaller circle on which the planet traveled around the deferent was called an epicycle. To explain all the known motions, Ptolemy was forced to use 28 circles. Epicycle Motion
22 As the planet moves around the epicycle, it is also traveling along the deferent. This causes the retrograde motion of the planets (points 3 to 5 in the diagram to the right). This is a way to diagram how Ptolemy s theory would work. Ptolemaic Model
23 200 A.D. Ptolemy realized that the planets were a lot closer to Earth than the stars, but he still believed in the existence of celestial spheres. Stars and planets were attached to these spheres. He also realized there might be other objects outside the sphere of fixed stars.
24 200 A.D. So, Ptolemy proposed there were other spheres outside those visible. Ended with the Primum Mobile (God), which provided the motions of the other spheres. This was the first mathematical attempt to explain nature.
25 ~ 410 A.D. Alexandria burns and is destroyed along with most of the records in the library. Loss of most knowledge acquired by the Greeks and Romans. Roman culture collapses leading to the Dark Ages. Roman Catholic Church absorbs Aristotle s scientific method and Ptolemy s model of the universe. Ancient Lighthouse at Alexandria
26 ~ 1500 s The Renaissance People returned to scientific values where new ideas were more important than religious beliefs. Art and science began to flourish. Da Vinci, Copernicus, Raphael, and others served the church, but they began to rebel (secretly).
27 ~ 1500 s Nicholas Copernicus Reinvented the heliocentric model. More than just an attempt to solve retrograde motion. It had both social and political consequences by challenging the power of the Catholic Church. Psalm 93 Thou hast fixed the Earth immovable and firm.
28 ~ 1500 s Copernicus model also questioned the authority of the most revered wise men of the ancient world (Ptolemy, Plato, Heraclides). He forced a change in humanity s view of the world and our importance in it. Yet, even his model had problems.
29 ~ 1500 s Copernicus still used circular orbits. As a result, he still was forced to use epicycles and deferents. His model was even more complicated than Ptolemy s. Would have failed our modern criteria that models be as simple as possible (Occam s Razor).
30 Tycho Brahe 1 st true observer. Built the Danish Observatory Measured the positions of planets and the stars to a very high degree of accuracy for his time. He also used trigonometry to measure the distance to the Sun.
31 1600 s Johannes Kepler A student of Tycho Brahe with access to all of Brahe s data. Used this data to formulate the Laws of Planetary Motion. He was the first to realize that orbits were elliptical. Theory fit the data, not the other way around.
32 1600 s Solved one problem of heliocentric model. Eliminated the need for epicycles and deferents.
33 1600 s This highly accurate system determining all the motions of the planets marked the beginning of the clockwork universe concept.
34 First Law The orbits of celestial objects (planets) are ellipses. The Sun is not in the center, but at one of the two foci of the ellipse. No matter where you are on the ellipse, the sum of the distances from the foci to the object is constant. This ellipse is exaggerated, they are very close to being circular.
35 Second Law The planets sweep out equal areas in equal times. If you look at the shaded areas to the right, those two areas are equal to each other. Which means the planet moves slightly faster in its closest pass to the Sun, slower farther away. Kepler's Laws with Animation
36 The square of a planet s orbital period is proportional to the cube of its average distance from the Sun. The period is time of revolution. The radius can be miles, kilometers, or astronomical units. Third Law
37 Examples of 3 rd Law Planet Period A.U. T² R³ Mercury Venus Earth Mars Jupiter Saturn Period = Earth Years T² = Period Squared R³ = Average Radius of Orbit (A.U.) Cubed
38 You Do The Math The A.U. of a planet is About how long will it take the planet to orbit the Sun? 2.53³ = The square root of = 4.02 Earth Years
39 1620 s Galileo Finished off the idea of a geocentric universe. Used a telescope to make the following discoveries: 1. Sunspots 2. Mountains on the Moon 3. Milky Way with Lots of Stars 4. Venus had Phases Like Our Moon 5. Jupiter s Four Main Moons
40 1620 s Most damaging discovery was the four moons of Jupiter. Those moons were orbiting Jupiter instead of the Earth. This did not fit the idea of a geocentric model. At this point, the Catholic Church was forced to give in and accept a heliocentric model. Began the decline of religion.
41 1680 s Isaac Newton One of the most intelligent men in history. Two main applications to Astronomy. 1. Law of Universal Gravitation 2. Laws of Motion
42 Law of Universal Gravitation Simply put every object in the universe has a gravitational attraction for every other object. An atom in your fingernail has a gravitational pull on the Moon!
43 Law of Universal Gravitation Newton developed a formula to go with the Law. F = G M 1 M 2 / r² F = force of attraction; G = gravitational constant; M 1 = mass of 1 st body; M 2 = mass of 2 nd body; r² = the distance between the two bodies squared.
44 Law of Universal Gravitation The gravitational constant is a very small number. It is for this reason you can t feel a gravitational pull between you and another person. Mass has a role as well, you may pull on the Moon, but your mass is so small there is no apparent change in its orbit.
45 Law of Universal Gravitation Lets look at an mathematical example. It will not be precise, because the gravitational constant is a lot smaller than the number we will use for this example. What is the attractive force (F) of two bodies in space with the following information: G = M 1 = 500 kg; M 2 = 3000 kg R = 10 m
46 Law of Universal Gravitation Remember the formula: F = G M 1 M 2 / r² 500 kg x 3000 kg = 1,500,000 kg 1,500,000 kg x = 90 kg (10m)² = 100m² 90 kg 100m² = 0.9 kg/m² This is a very small amount of force between two huge objects that are very close. Imagine if we used the real G or the objects were a lot farther apart! Try it at a distance of 100 m apart!
47 Law of Universal Gravitation Remember the formula: F = G M 1 M 2 / r² 500 kg x 3000 kg = 1,500,000 kg 1,500,000 kg x = 90 kg (100m)² = 10,000m² 90 kg 10,000m² = kg/m² The distance increased by a factor of 10, the force decreased by a factor of 100! Try to imagine the force between the two objects at astronomical distances! It is very tiny, but still there.
48 Law of Universal Gravitation This law also predicts that, in general, the orbit of an object can be any of four conic sections as well as a straight line. Conic sections are slices thru a cone at different angles.
49 Law of Universal Gravitation Scientists have discovered some comets that have parabolic or hyperbolic orbits. In these cases, they do not return to the Sun after they pass by it.
50 Laws of Motion We have looked at the Laws of Motion in Motion Unit. Will not go over them again. Necessary for spaceflight.
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
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
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
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
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).
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
Benefit of astronomy to ancient cultures Usefulness as a tool to predict the weather (seasons) Usefulness as a tool to tell time (sundials) Central Africa (6500 B.C.) Alignments Many ancient cultures built
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
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
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
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!
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.
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
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
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
Gravitation and the Waltz of the Planets Chapter Four 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
Gravitation and the Waltz of the Planets Chapter Four 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
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
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,
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
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?
The following notes roughly correspond to Section 2.4 and Chapter 3 of the text by Bennett. This note focuses on the details of the transition for a geocentric model for understanding the universe to a
The Copernican Revolution ASTR 1010 Spring 2016 Study Notes Dr. Magnani The Copernican Revolution is basically how the West intellectually transitioned from the Ptolemaic geocentric model of the Universe
Gravity Newton s Law of Gravitation Kepler s Laws of Planetary Motion Gravitational Fields Simulation Synchronous Rotation https://www.youtube.com/watch?v=ozib_l eg75q Sun-Earth-Moon System https://vimeo.com/16015937
1. Evolution of the Solar System Nebular hypothesis, p 10 a. Cloud of atoms, mostly hydrogen and helium b. Gravitational collapse contracted it into rotating disc c. Heat of conversion of gravitational
BROCK UNIVERSITY Page 1 of 10 Test 1: November 2014 Number of pages: 10 Course: ASTR 1P01, Section 2 Number of students: 961 Examination date: 7 November 2014 Time limit: 50 min Time of Examination: 17:00
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
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
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
BROCK UNIVERSITY Page 1 of 10 Test 1: November 2014 Number of pages: 10 Course: ASTR 1P01, Section 2 Number of students: 30 Examination date: 10 November 2014 Time limit: 50 min Time of Examination: 9:00
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
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
Week 3: Chapter 3 The Science of Astronomy This Week... The Copernican Revolution The Birth of Modern Science Chapter 2 Walkthrough Discovering the solar system Creating a clockwork Universe 3.1 The Ancient
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
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
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
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
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
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
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
The History of Astronomy The History of Astronomy Earliest astronomical record: a lunar calendar etched on bone from 6500 B.C. Uganda. Also we find early groups noted the Sun, Moon, Mercury, Venus, Earth,
ASTRONOMY 1 EXAM 1 Name Identify Terms - Matching (20 @ 1 point each = 20 pts.) 1 Solar System G 7. aphelion N 14. eccentricity M 2. Planet E 8. apparent visual magnitude R 15. empirical Q 3. Star P 9.
Astronomy Phys 181 Midterm Examination Choose the best answer from the choices provided. 1) What is the range of values that the coordinate Declination can have? (a) a) -90 to +90 degrees b) 0 to 360 degrees
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
Reading: OpenStax, Chapter 2, Section 2.2 &2.4, Chapter 3, Sections 3.1-3.3 Chapter 5, Section 5.1 Last time: Scales of the Universe Astro 150 Spring 2018: Lecture 2 page 1 The size of our solar system,
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
The History of Astronomy Please pick up your assigned transmitter. When did mankind first become interested in the science of astronomy? 1. With the advent of modern computer technology (mid-20 th century)
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
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
Space Notes Covers Objectives 1 & 2 Space Introduction Space Introduction Video Celestial Bodies Refers to a natural object out in space 1) Stars 2) Comets 3) Moons 4) Planets 5) Asteroids Constellations
Upon Whose Shoulders We Stand: A History of Astronomy Up to 200 A.D. Dick Mallot 3/17/2005 Who were these ancient astronomers? Where did real astronomy begin? What did we know about astronomy 2000+ years
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.)
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
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
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?
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:
~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
Kepler s Laws Simulations Goto: http://csep10.phys.utk.edu/guidry/java/kepler/kepler.html 1. Observe the speed of the planet as it orbits around the Sun. Change the speed to.50 and answer the questions.
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
Today FIRST HOMEWORK DUE Ancient Astronomy Competing Cosmologies Geocentric vs. Heliocentric Ptolemy vs. copernicus Retrograde Motion Phases of Venus Galileo 1 3.1 The Ancient Roots of Science Our goals
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
Early Ideas of the Universe Though much of modern astronomy deals with explaining the Universe, through History astronomy has dealt with such practical things as keeping time, marking the arrival of seasons,
Motions of the Planets ( Wanderers ) Planets move on celestial sphere - change RA, Dec each night - five are visible to naked eye Mercury, Venus, Mars, Jupiter, Saturn Days of the week: - named after 7
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
Lecture 2 : Early Cosmology Getting in touch with your senses Greek astronomy/cosmology The Renaissance (part 1) 8/28/13 1 Sidney Harris Discussion : What would an unaided observer deduce about the Universe?
Module 3: Astronomy The Universe The Age of Astronomy was marked by the struggle to understand the placement of Earth in the universe and the effort to understand planetary motion. Behind this struggle
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
Ast ch 4-5 practice Test Multiple Choice 1. The distance from Alexandria to Syene is about 500 miles. On the summer solstice the sun is directly overhead at noon in Syene. At Alexandria on the summer solstice,
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 3 The Science of Astronomy 1 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?
Contents: -Information/Research Packet - Jumbled Image packet - Comic book cover page -Comic book pages -Example finished comic Nicolaus Copernicus Nicholas Copernicus was a Polish astronomer who lived
HISTORY OF ASTRONOMY, PART 1 How our understanding of the Universe has changed Focus Question: How and why has our understanding of the universe changed over time? The oldest science? As far back as the
BROCK UNIVERSITY Page 1 of 10 Test 2: November 2015 Number of pages: 10 Course: ASTR 1P01, Section 2 Number of students: 861 Examination date: 7 November 2015 Time limit: 50 min Time of Examination: 13:00
ASTRO 6570 Lecture 1 Historical Survey EARLY GREEK ASTRONOMY: Earth-centered universe - Some radical suggestions for a sun-centered model Shape of the Earth - Aristotle (4 th century BCE) made the first
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
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,