Q1 Test 1 Study Guide
Heliocentric vs. Geocentric, pre-Newton
Reading: In-Class Test on Friday, Aug 10
Nature of Science 1. Scientific statements must be falsifiable. Define falsifiable. Explain the difference between falsifiable and false. 2. Give an example of two things that are falsifiable, but not false. State one testable hypothesis for each. 3. What must scientists do with a hypothesis when (repeated) tests do not match the hypothesis’s testable predictions? 4. Explain how scientists can gain confidence in their hypotheses. Can a hypothesis ever be proven true? 5. State the Cosmological Principle. Is the Cosmological Principle falsifiable? Is it necessarily true? Explain your answers.
Daily Celestial Motions
1. Define the following: equator, latitude, horizon 2. Describe or sketch the apparent motions of the stars during the course of a night as seen from Chandler when looking in each of the four cardinal directions (N, S, E, W). 3. Describe how to find the North Celestial Pole by watching the motions of the stars throughout the night. 4. Describe how to locate Polaris (the north star) from Chandler, AZ. Where in the sky (what direction) should you look? (You can see Polaris on a clear night; it’s the bright star at the end of the little dipper.) 5. Describe the relationship between a location’s latitude and the direction of the North Celestial Pole at that location. 6. Draw a picture of the Earth surrounded by the (fictional) celestial sphere and label the following: North and South Poles, Equator, North and South Celestial Poles, Celestial equator. 7. Is the North Celestial Pole a location, or a direction? On your picture, draw an arrow representing the North Celestial Pole as observed from different locations on Earth. 8. What is the celestial sphere? From the motions of the stars – as visible to the naked eye – can we tell whether the celestial sphere is fact or fiction? Explain your answer.
Annual Celestial Motions & Seasons
1. Explain the difference between daily celestial motions and annual celestial motions. Give examples of each. Which are caused by the rotation of the Earth around its axis? Which are caused by the Earth’s orbit around the Sun? 2. Describe how the positions of the constellations in the night sky change during the year. Are they the same or different during different seasons? Does each constellation rise earlier or later each night? 3. Write an explanation or draw a picture to explain how the changes in the constellations that are seen during the year are caused by the Earth’s orbit around the Sun. 4. Describe how the position of the Sun in the sky changes during the course of the year. When during the year is the Sun north of the Celestial Equator, when it is south of it?
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Q1 Test 1 Study Guide
5. Define the ecliptic. Sketch the ecliptic and the Celestial Equator on a diagram of the celestial sphere. 6. When during the year are the days the longest? The shortest? 7. Describe two reasons why it is hotter in the summer than in the winter. (Hint: The Earth is actually slightly closer to the Sun during the winter.) 8. Draw a figure showing the motion of the Earth around the Sun. Label the equinoxes and solstices and describe what is special about each. (Don’t forget to indicate the tilt of the Earth’s axis.) 9. Describe how the Sun’s apparent motion throughout the year is explained in the geocentric model and in the heliocentric model.
Planetary Motions
1. Describe how ancient astronomers identified the planets. How were they different from the stars? 2. Describe the Geocentric model of the Solar System. How are the apparent motions of the Sun and Stars explained in this model? 3. Describe the Heliocentric model of the Solar System. How are the apparent motions of the Sun and Stars explained in this model? 4. Describe the contributions of each of the following people to understanding planetary motions: Ptolemy, Copernicus, Galileo 5. Describe the retrograde motion of a planet. 6. How are retrograde motions explained in the geocentric model? What is an epicycle? 7. How are retrograde motions explained in the heliocentric model? (A picture might help.) 8. Explain the difference between retrograde motion and epicycles. Which is an observation? Which is part of a model? 9. When Copernicus published On the Revolutions of the Heavenly Spheres, did astronomical data favor one model (Heliocentric or Geocentric) over the other? Why did Copernicus prefer the Heliocentric model? 10. State Occam’s razor and then explain what it means. Explain what the word simpler mean in the context of Occam’s razor.
Stellar parallax
1. Define parallax and describe the relationship between parallax and the distance to an object. 2. Draw a picture to explain the relationship between parallax and the distance to an object. 3. Did ancient astronomers understand the idea of parallax? Could they observe stellar parallax? 4. Explain why the lack of observed stellar parallaxes was an argument against a Heliocentric solar system. 5. Describe why modern astronomers can observe stellar parallax while ancient astronomers could not. (What technological advance made observing stellar parallax possible?)
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Q1 Test 1 Study Guide
Galileo’s Observations
1. Explain how Galileo’s observations of each of the following challenged the Geocentric model – Jupiter’s moons, sunspots and craters on the Moon, the phases of Venus 2. How many Galilean moons does Jupiter have? Describe how Galileo’s observations show that these moons orbit Jupiter. 3. Draw the Moon’s orbit around the Earth, as viewed from above the Earth’s North Pole. Label the location of a New Moon, 1st and 3rd quarter moons and the Full Moon. 4. Draw Venus’s orbit in both the geocentric and heliocentric models of the solar system. Use the drawings to show what Venus’s phases would be for each model. 5. When Galileo observed the phases of Venus, what did he see? Can Galieo’s observations be explained in the Ptolemaic model of the solar system? 6. Describe the Tychonic model of the Solar System and explain how it accommodates Galileo’s observations of the phases of Venus. Explain why Tycho Brahe objected to the Heliocentric model.
Introduction to Motion 1. Describe what each of the following people contributed to understanding motion: Aristotle, Galileo, Descartes 2. List the three types of motion in Aristotle’s physics and give an example of each. Are these the correct laws of motion? 3. Describe the differences between Aristotle’s and Galileo’s laws for falling objects. 4. For each of the following, determine which object falls faster A baseball or a ball bearing? A hammer or a feather through the air? A baseball or a piece of paper? A hammer or a feather in a vacuum?
5. Describe how Galileo would explain the outcome of dropping each of the above pairs. Could Aristotle’s law for falling objects explain each comparison? 6. According to Aristotle, a push is required to keep an object moving. “If you shoot an arrow, it can travel a great distance horizontally while hardly slowing down.” Can Aristotle’s view of motion explain this? Explain your answer. 7. Describe Galileo’s thought experiment with ramps. Did Galileo agree with Aristotle’s belief that objects require a push to keep moving? Explain your answer. 8. Describe how Descartes imagined motion would in the absence of gravity? How did he imagine the motion of a stone (or an apple) in the absence of gravity?
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