1 / 23

ASTR 1101-001 Spring 2008

ASTR 1101-001 Spring 2008. Joel E. Tohline, Alumni Professor 247 Nicholson Hall [Slides from Lecture11]. Exam #1 Results. Total score composed of two parts: (g1) score on scale-model homework assignment is 25% (g2) score on in-class exam is 75% Where to find scores: g1 at bottom of exam

zuri
Télécharger la présentation

ASTR 1101-001 Spring 2008

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ASTR 1101-001Spring 2008 Joel E. Tohline, Alumni Professor 247 Nicholson Hall [Slides from Lecture11]

  2. Exam #1 Results • Total score composed of two parts: • (g1) score on scale-model homework assignment is 25% • (g2) score on in-class exam is 75% • Where to find scores: • g1 at bottom of exam • g2 at top-left of exam Example: g1 = 17/25; g2 = 23/27  grade = 25*g1 + 75*g2 = 89

  3. Contrasting Models of Planetary Motions • Greek Geocentric Model (Ptolemaic System) – §4-1 • Originated by Apollonius of Perga & Hipparchus in 2nd century B.C. • Expanded upon by Ptolemy in 2nd century A.D. • Copernican Heliocentric Model – §4-2 • Proposed in 1543 by Nicolaus Copernicus • (Also considered in 3rd century B.C. by Aristarchus)

  4. Contrasting Models of Planetary Motions • Geocentric Model • Underlying hypothesis: Earth is unmoving and at “center of the universe” • Heliocentric Model • Preferred (by Copernicus) initially because of its relative simplicity • Eventually proven correct by new observations made possible by the aid of telescopes (see Galileo’s discoveries §4-5)

  5. Observation/Explanation • OBSERVATION #1: Stars (and Sun, Moon, etc.) rise in east and set in west once every 24 hours • EXPLANATION (Ptolemy): Celestial sphere spinning east-to-west about a stationary Earth every 24 hours • EXPLANATION (Copernicus): Earth spins west-to-east once on its axis every 24 hours

  6. Observation/Explanation • OBSERVATION #2: Remove 24-hr diurnal motion; Sun and Moon both move steadily west-to-east at different rates (Moon = month period; Sun = year period) • EXPLANATION (Ptolemy): Sun and Moon both orbit the Earth • EXPLANATION (Copernicus): Moon orbits Earth (monthly) but Earth orbits Sun (yearly)

  7. Observation/Explanation • OBSERVATION #3: Superior planets [Mars, Jupiter, Saturn] usually wander slowly east-to-west (observed periods greater than 1 year) but periodically display retrograde (west-to-east) motion • EXPLANATION (Ptolemy): Planets orbit Earth via a combination of circular motions (deferent + epicycle) • EXPLANATION (Copernicus): Planets orbit the Sun at distances greater than 1 AU and with velocities less than the Earth’s

  8. Observation/Explanation • OBSERVATION #3: Superior planets [Mars, Jupiter, Saturn] usually wander slowly east-to-west (observed periods greater than 1 year) but periodically display retrograde (west-to-east) motion • EXPLANATION (Ptolemy): Planets orbit Earth via a combination of circular motions (deferent + epicycle) • EXPLANATION (Copernicus): Planets orbit the Sun at distances greater than 1 AU and with velocities less than the Earth’s

  9. Observation/Explanation • OBSERVATION #3: Superior planets [Mars, Jupiter, Saturn] usually wander slowly east-to-west (observed periods greater than 1 year) but periodically display retrograde (west-to-east) motion • EXPLANATION (Ptolemy): Planets orbit Earth via a combination of circular motions (deferent + epicycle) • EXPLANATION (Copernicus): Planets orbit the Sun at distances greater than 1 AU and with velocities less than the Earth’s

  10. Observation/Explanation • OBSERVATION #4: Inferior planets [Mercury, Venus] never wander very far (in angular separation) from the Sun; only seen shortly before or shortly after sunrise/sunset • EXPLANATION (Ptolemy): Planet deferents rotate together with the Sun • EXPLANATION (Copernicus): Planets orbit the Sun at distances less than 1 AU

  11. Observation/Explanation • OBSERVATION #4: Inferior planets [Mercury, Venus] never wander very far (in angular separation) from the Sun; only seen shortly before or shortly after sunrise/sunset • EXPLANATION (Ptolemy): Planet deferents rotate together with the Sun • EXPLANATION (Copernicus): Planets orbit the Sun at distances less than 1 AU

  12. Observation/Explanation • OBSERVATION #4: Inferior planets [Mercury, Venus] never wander very far (in angular separation) from the Sun; only seen shortly before or shortly after sunrise/sunset • EXPLANATION (Ptolemy): Planet deferents rotate together with the Sun • EXPLANATION (Copernicus): Planets orbit the Sun at distances less than 1 AU

More Related