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Homework Help: Reflecting telescope optics problem-Angle on the sky to angle on a mirror

  1. Dec 2, 2012 #1
    1. The problem statement, all variables and given/known data

    When viewed from Earth, the Moon subtends an angle of 0.5° in the sky. How large an image of the Moon will be formed by the 3.6 m diameter mirror of the Canada-France-Hawaii Telescope, which has a focal length of 8.5 m?

    2. Relevant equations

    1/s + 1/s' = 1/f, but I'm not sure what else.

    3. The attempt at a solution

    I'm really not sure where to begin. My book only talks about refracting telescopes and we've yet to talk about reflecting telescopes in class. I thought initially it might have something to do with the distance to and radius of the moon but I couldn't figure out how to work those into the problems. I'd appreciate any help you have. Thanks!
  2. jcsd
  3. Dec 3, 2012 #2
    The angle the object subtended at the mirror is the same angle that the image subtends - just like for refracting telescopes.

    Attached Files:

    Last edited: Dec 3, 2012
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