20130316

Astronomy midterm question: best kind of telescope for a beginner?

Astronomy 210 Midterm 1, spring semester 2013
Cuesta College, San Luis Obispo, CA

[20 points.] An astronomy question on an online discussion board(*) was asked and answered:
Kasey: What is the best kind of telescope for a beginner? I want something you can see a lot of things with.
Larry454: You mentioned that you want to be able to see a lot of things. Most astronomical targets are not hard to see because they are too small, they are hard to see because they are too dim. So this means you want a large diameter telescope.
Discuss why this telescope purchasing advice is correct, and the criteria used in your decision. Support your answer using the properties of telescopes and telescope powers.

*Adapted from: http://answers.yahoo.com/question/index?qid=20101126084506AAu2hxx.

Solution and grading rubric:
  • p = 20/20:
    Correct. Discusses how diameter of primary mirror determines the light-gathering power, such that a large diameter mirror would result in making dimmer objects brighter. May also discuss other powers as well (resolving power, magnyfing power).
  • r = 16/20:
    Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors.
  • t = 12/20:
    Contains right ideas, but discussion is unclear/incomplete or contains major errors.
  • 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 30674
Exam code: midterm01n4sT
p: 29 students
r: 1 student
t: 1 student
v: 0 students
x: 0 students
y: 0 students
z: 0 students

Section 30676
Exam code: midterm01sAb1
p: 44 students
r: 1 student
t: 1 student
v: 0 students
x: 0 students
y: 0 students
z: 0 students

A sample "p" response (from student 1934):

Another sample "p" response (from student 3792):

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