Astronomy midterm question: ideal/non-ideal viewing conditions

Astronomy 210 Midterm 1, Fall Semester 2009
Cuesta College, San Luis Obispo, CA

[20 points.] Consider the following excerpt regarding viewing stars and planets at night:

"When [Harry, Ron, Hermione] reached the top of the Astronomy Tower at eleven o'clock they found a perfect night for stargazing, cloudless and still. The grounds were bathed in silvery moonlight... Each of them set up his or her telescope and...entered the precise positions of the stars and planets they were observing..."
--J. K. Rowling, Harry Potter and the Order of the Phoenix, Scholastic, New York, NY, 2003, pp. 718-719.

Discuss both the ideal and non-ideal conditions that would have affected telescopic observations on that night. Support your answer using factors that relate to the three telescope powers.

Solution and grading rubric:

• p = 20/20:
  Correct. Ideal: lack of atmospheric turbulence means that resolving power is not adversely affected. Non-ideal: moonlight will adversely affect the light-gathering power to image fainter stars.
  
• r = 16/20:
  Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. Discusses both ideal and non-ideal factors, but one citation from excerpt is problematic; or most generally discusses all factors that may affect viewing, but does not specifically apply it to the excerpt.
  
• t = 12/20:
  Contains right ideas, but discussion is unclear/incomplete or contains major errors. Correctly discusses only one of the ideal/non-ideal conditions specified in the excerpt.
  
• v = 8/20:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner.
  
• x = 4/20:
  Implementation/application of ideas, but credit given for effort rather than merit.
  
• y = 2/20:
  Irrelevant discussion/effectively blank.
  
• z = 0/20:
  Blank.
  

Grading distribution:
Section 70158
p: 22 students
r: 10 students
t: 20 students
v: 2 students
x: 0 students
y: 0 students
z: 0 students

A sample "p" response (from student 2522):

A sample "r" response (from student 7392), neglecting to address the light-pollution caused by moonlight, but also citing additional details from the book not specifically included in the above excerpt: