20180310

Astronomy midterm question: Canis Minor and Canis Major at peak of visibility?

Astronomy 210 Midterm 1, spring semester 2018
Cuesta College, San Luis Obispo, CA

An astronomy magazine article[*] describes the positions of constellations in the sky at a certain time of year:
Every year, the constellations Canis Minor and Canis Major come to their early-evening peak of visibility in the night sky as winter winds down.
Discuss a plausible date and time for an observer in San Luis Obispo, CA to make this observation of Canis Minor and Canis Major in the sky. If there is no such plausible date and time, then explain why. Defend your answer by clearly explaining how you used your starwheel to do this, along with any assumptions that you may have made. (Ignore daylight saving time.)

[*] "Sky Maps: December 2017-December 2018," Skywatch (2018), p. 16.

Solution and grading rubric:
  • p:
    Correct. Discussion includes the following:
    1. turns starwheel such that Canis Minor and Canis Major are along the meridian (already at their peak of visibility) or rising from the east/southeast horizon (coming to their peak of visibility); and
    2. reads off a plausible early evening time (5 PM-9 PM?) that corresponds with a date near or at the end of winter (January-March or even April?).
    Has argument on plausibility (or implausibility) that is consistent with these constraints.
  • r:
    Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. May have:
    1. Canis Minor and Canis Major past their peak visibility (low in the west); or
    2. picked a time during the night that is not early evening (such as midnight), or at best a late afternoon time just before sunset.
    Still has argument on plausibility (or implausibility) that is consistent with these misinterpretations of the given constraints.
  • t:
    Contains right ideas, but discussion is unclear/incomplete or contains major errors. Typically has both (3) and (4) above, but still has consistent argument on plausibility (or implausibility).
  • v:
    Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. At least attempts to use starwheel in a systematic manner.
  • x:
    Implementation/application of ideas, but credit given for effort rather than merit. Discussion not clearly based on using a starwheel in a systematic manner.
  • y:
    Irrelevant discussion/effectively blank.
  • z:
    Blank.
Grading distribution:
Section 30676
Exam code: midterm01sNuB
p: 27 students
r: 12 students
t: 5 students
v: 1 student
x: 0 students
y: 0 students
z: 0 students

A sample "p" response (from student 2536)

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