Copernican vs Ptolemaic Models
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Questions and Answers

What is the Sun's altitude if you can fit 3 fists between the horizon and the Sun’s position?

  • 15°
  • 45°
  • 60°
  • 30° (correct)

    • What fraction of the width of your finger would span the length of the Moon if its angular length is 0.5°?

  • 1/6
  • 1/36
  • 1/24
  • 1/12 (correct)

    • What was believed to be the origin of the December 21, 2012, apocalypse theory?

  • A prediction from ancient Greek texts
  • A calendar reset in the Mayan system (correct)
  • An astronomical alignment of planets
  • A prophecy from ancient Egyptian texts

    • What facilitated the ability of the Maya to track patterns in celestial events?

    <p>Their base-20 number system</p> Signup and view all the answers

    Why are crescent moons primarily seen during the day?

    <p>The Sun's brightness overshadows them</p> Signup and view all the answers

    What is the Moon's phase during a solar eclipse?

    <p>New Moon</p> Signup and view all the answers

    Where is an observer standing if they see a total solar eclipse?

    <p>In the umbra</p> Signup and view all the answers

    What is the cause of a lunar eclipse?

    <p>The Earth moves between the Sun and Moon</p> Signup and view all the answers

    What assumption about space led Ptolemy to underestimate the size of our visible planetary system?

    <p>The belief that Earth was the center of the universe</p> Signup and view all the answers

    What are the three features of apparent planetary motion discussed in the lecture?

    <p>Retrograde motion, brightness variation, and circular paths</p> Signup and view all the answers

    According to Aristotle, what is everything in the celestial realm composed of?

    <p>Aether, which is unchanging and eternal</p> Signup and view all the answers

    What did Eudoxus propose regarding where planets reside in space?

    <p>On concentric spheres rotating around the Earth</p> Signup and view all the answers

    How did Aristotle explain the daily motion of the sky?

    <p>By the movement of the stars across a fixed celestial sphere</p> Signup and view all the answers

    What characteristic of Apollonius' epicycle model explains the retrograde motion of planets?

    <p>The combination of circular orbits and smaller epicycles</p> Signup and view all the answers

    What is the key difference between a sidereal year and a solar year?

    <p>The reference point used for measurement</p> Signup and view all the answers

    What was Aristotle's explanation for the source of all motion in the celestial realm?

    <p>The existence of a prime mover or an unchanging entity</p> Signup and view all the answers

    What determines the rotation of stars in the night sky from the North Pole?

    <p>The Earth's rotation on its axis</p> Signup and view all the answers

    What happens to the center of the Southern stars' rotation as one travels south of the equator?

    <p>It rises higher in the sky</p> Signup and view all the answers

    Why are different stars and constellations visible at various times of the year?

    <p>The Earth changes its position in relation to the stars</p> Signup and view all the answers

    What marks the North and South Celestial Poles?

    <p>Polaris and Sigma Octantis</p> Signup and view all the answers

    What celestial event does Newgrange align with?

    <p>Winter Solstice</p> Signup and view all the answers

    Why was the star Sirius significant to the Ancient Egyptians?

    <p>It indicated the flooding of the Nile River</p> Signup and view all the answers

    Why do we now use the Gregorian calendar instead of the Julian calendar?

    <p>The Gregorian calendar has a more accurate leap year system</p> Signup and view all the answers

    What celestial event is Stonehenge aligned to, and what occurs there during this event?

    <p>Winter Solstice, sunlight illuminates the altar</p> Signup and view all the answers

    What is the primary reason that lunar eclipses are seen more frequently than solar eclipses?

    <p>Lunar eclipses can be seen from anywhere on the night side of the Earth.</p> Signup and view all the answers

    What term describes the period when eclipses can potentially occur?

    <p>Saros Cycle</p> Signup and view all the answers

    During what phase of Venus does a heliacal rise occur?

    <p>When Venus rises just before the Sun</p> Signup and view all the answers

    Which characteristic of the planet Venus led the Maya to regard it as a special star?

    <p>Its brightness and regularity of appearance</p> Signup and view all the answers

    Why did ancient Babylonian astronomers study the sky?

    <p>To improve agricultural planning based on seasonal climates</p> Signup and view all the answers

    What is the significance of the Mayan Dresden codex in relation to astronomical predictions?

    <p>It shows the Mayan understanding of eclipse cycles.</p> Signup and view all the answers

    How do the numbers in our time and angle units relate to historical astronomy?

    <p>They stem from the Babylonians' 60-based numeral system.</p> Signup and view all the answers

    What happens to Venus approximately 8 months after its bright heliacal rise?

    <p>It starts to dim and transition into the evening sky.</p> Signup and view all the answers

    What is Kepler's 1st Law concerning planetary orbits?

    <p>Planets orbit the Sun in ellipses with the Sun at one focus.</p> Signup and view all the answers

    What does the term 'eccentricity' refer to in an ellipse?

    <p>The measure of how much an orbit deviates from being circular.</p> Signup and view all the answers

    What is the definition of 'perihelion'?

    <p>The point in an orbit closest to the Sun.</p> Signup and view all the answers

    How did Kepler relate planetary orbits to musical intervals?

    <p>He discovered that planetary distances corresponded to musical notes.</p> Signup and view all the answers

    What is the semi-major axis of an ellipse?

    <p>The longest radius of the ellipse.</p> Signup and view all the answers

    Why do planets experience changes in speed according to Kepler's 2nd Law?

    <p>The gravitational pull of the Sun varies with distance.</p> Signup and view all the answers

    What is a key characteristic of the Rudolphine Tables?

    <p>They were created by Johannes Kepler with remarkable accuracy.</p> Signup and view all the answers

    What causes the seasons on Earth?

    <p>The axial tilt of Earth relative to its orbit around the Sun.</p> Signup and view all the answers

    What did Tycho Brahe conclude about the reliability of the crystal orbs after observing the Great Comet of 1577?

    <p>They did not exist, challenging the prevailing beliefs of the time.</p> Signup and view all the answers

    How did Tycho’s search for stellar parallax influence his view on the motion of the Earth?

    <p>He concluded that the Earth was motionless based on parallax observations.</p> Signup and view all the answers

    What is an 'Astronomical Unit' (AU)?

    <p>The average distance from the Earth to the Sun.</p> Signup and view all the answers

    What models did Kepler present in his work 'Cosmographic Mystery'?

    <p>A heliocentric model with elliptical orbits.</p> Signup and view all the answers

    Why did Tycho hire Johannes Kepler?

    <p>To provide mathematical proof for his observational data.</p> Signup and view all the answers

    How did Kepler’s laws of planetary motion differ from earlier theories?

    <p>They introduced the concept of elliptical orbits.</p> Signup and view all the answers

    What was a significant contradiction that Tycho discovered regarding the supernova of 1572?

    <p>It varied in brightness over time, suggesting change in the heavens.</p> Signup and view all the answers

    Why is it difficult to observe stellar parallax with the naked eye?

    <p>The angle of parallax is extremely small and not perceivable.</p> Signup and view all the answers

    Study Notes

    Copernican Model

    • Copernicus proposed a heliocentric model, where planets orbit the Sun.
    • This differed from the Ptolemaic model, which placed Earth at the center.
    • Copernicus's model was based on the observation that some features of the Ptolemaic models were inaccurate.

    Ptolemaic Model Issues

    • The Ptolemaic model used epicycles to explain retrograde motion.
    • The model's explanation had complications, and Copernicus saw those as flaws.

    Copernicus's Orbits

    • Copernicus believed planets moved in circular orbits around the Sun.
    • Planetary motion wasn't at a constant speed, but rather varied.

    Components of Earth's Motion

    • In Copernicus's model, Earth's motion includes revolution around the Sun, rotation on its axis, and a tilt in its axis.
    • This accurately reflects the retrograde motion observed in the sky.

    Retrograde Motion Explanation

    • Retrograde motion, where planets appear to move backward in the sky, was explained as an illusion caused by Earth's relative motion to the planets.
    • Earth's faster motion overtaking other planets creates the illusion of backwards movement.

    Planet Brightness and Speed

    • Planets appear to slow down and increase in brightness when they are in retrograde motion (in Copernicus's system).
    • This is because the Earth is overtaking the planet in its orbit, resulting in a change of perspective.

    Order of Planets

    • Copernicus placed the planets in the following order starting from the Sun: Mercury, Venus, Earth, Mars, Jupiter, and Saturn.

    Mercury and Venus Motion

    • Mercury and Venus orbit the Sun inside Earth's orbit, which accounts for their different orbital behaviors compared to outer planets.

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    Description

    Explore the differences between the Copernican heliocentric model and the Ptolemaic geocentric model. This quiz covers key concepts such as planetary motion, retrograde motion, and the historical impact of Copernicus's theories. Test your understanding of these foundational astronomical models.

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