Overall Unit 2 Outline (from Syllabus)

• Unit 2: The Motions of the Earth, the Moon and the Planets. The scale of the Solar System. Kepler's Laws.
  • Note: A recurring theme in this unit…: In astronomy, objects are usually so big that you cannot get a tape measure very far around them. Or so far away that you have no hope of stretching a tape measure to them. How could you measure such circumferences or distances? Crafty use of trigonometry (staight lines, angles and triangles) is the recurring answer. In later units we will show astronomers' other crafty tricks.

Unit 2 Detailed Topic List

• 2020-02-28: Unit 1 Exam.
• 2020-03-02: An introduction to Ptolemy's (Earth-centered) view. The motion of the Moon (including the names of the phases). The way the Moon being lit by the Sun results in the various shapes (full, gibbous, crescent). The lunar orbit of 27.3 days (“sidereal lunar cycle” one lunar orbit) vs. the lunar month of 29.5 days (“synodic lunar cycle”, time between new moons). Slides: Ptolemaic Model, Moon Phases. YouTube Animation: Ptolemaic Model, Epicycles. YouTube Animation I did not use: Copernican Retrograde Motion from Principia Universi. Textbook Section 4.5: Moon Phases.
• 2020-03-04: Solar and Lunar Eclipses (Including Umbra, Penumbra, Relation to Phases of Moon). Slides: Eclipses. Retrograde Motion as Explained by the Copernican Model. Construction: Mars Retrograde. Textbook Section 4.7: Eclipses.
  • Note: The coming retrograde of Mars will last from Sep. 10 to Nov. 14 per AAPS Space, an astrology website.
• 2020-03-06: Circumference and Area of a Disk. Circumference, Surface Area, and Volume of a Sphere. The Pie Crust Formula. Construction: Aristarchus Size of Moon.
• 2020-03-09: Construction: Eratosthenes Size of Earth. Table: Solar System Sizes and Distances. Lawn-Sized Scale Model of the Solar System.
• 2020-03-11: Video: Black Rock Desert Scale Model of the Solar System. Kepler's 1st Law. Properties of Ellipses. Textbook Section 3.1: Kepler's Laws.
• 2020-03-13: Kepler's Second Law. The Astronomical Unit. Example: Earth's Maximum Speed from Minimum Speed and Eccentricity. Kepler's Third Law. Examples: Find P given a, or find a given P. Slides: Kepler's 2nd and 3rd Laws.
• 2020-03-16: Start Unit 3.
• 2020-03-18: Unit 2 Exam. Unit 2 Exam Solution.