Study Guide for Astronomy & Astrophysics I Exam 1 (Fall 2018)
 Be familiar with the Ptolemaic and Copernican models, especially the role of retrograde motion in each.
 Be able to identify the key orbital positions of planets (conjunctions, oppositions, greatest elongations) and what planets would look like as viewed from Earth.

Review ellipses,
relationships between semimajor axis, semiminor axis, eccentricity, and perihelion/aphelion
distances. Keep in mind that you can draw an ellipse with a string and two pins.
 Review the four conic sections, how they relate to orbit types, and what eccentricities correspond to them.
 Be familiar with magnitudes, distance modulus, absolute and apparent magnitude, parallax.
 Be able to explain how planets behave in their orbits, especially near perihelion and aphelion, in terms of distance, speed/velocity, angular momentum and energy.
 Review the concepts and equations of plate scale and angular size of features seen with a telescope/camera.
 Be familiar with kinetic energy, gravitational potential energy and the role of angular momentum.