Astronomy midterm question: "evening stars" visible as "morning stars?"

Astronomy 210 Midterm 1, spring semester 2015
Cuesta College, San Luis Obispo, CA

A view of the San Luis Obispo, CA sky is shown below for September 9, 2015 with the planets Saturn and Mercury.

Discuss which of these planets will be visible at sunrise the next day. If neither planet will be visible, then explain why. Support your answer using a diagram showing the positions of the sun, Saturn, Mercury, Earth, and an observer on Earth.

Solution and grading rubric:
  • p:
    Correct. Complete diagram (with the sun, Saturn, Mercury, and an observer on Earth), and discusses/demonstrates:
    1. places Saturn somewhere in an outer orbit such that it is visible high overhead at sunrise, and Mercury somewhere in an inner orbit to be low over the western horizon of the observer at sunset;
    2. at sunrise 12 hours later, Saturn and Mercury will both essentially be in their same locations in their orbits;
    3. thus both Saturn and Mercury would be below the horizon for an observer on Earth at sunrise, and thus not be visible.
  • r:
    Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. Two of three points (1)-(3) correct, one is problematic/incomplete.
  • t:
    Contains right ideas, but discussion is unclear/incomplete or contains major errors. Problems with either diagram or discussion. One of three points (1)-(3) correct.
  • v:
    Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Diagram and discussion problematic.
  • x:
    Implementation/application of ideas, but credit given for effort rather than merit. Misconceptions or non-relevant concepts.
  • y:
    Irrelevant discussion/effectively blank.
  • z:
Grading distribution:
Section 30674
Exam code: midterm01nR31
p: 8 students
r: 10 students
t: 12 students
v: 8 students
x: 0 students
y: 0 students
z: 0 students

A sample "p" response (from student 0622):

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