Question: Which of the following statements about light focusing is not true?

Answer: The focal plane of a reflecting telescope is always located within a few inches of the primary mirror.

Question: Suppose the angular separation of two stars is smaller than the angular resolution of your eyes. How will the stars appear to your eyes?

Answer: The two stars will look like a single point of light.

Question: Which of the following is a principal advantage of CCDs over photographic film?

Answer: CCDs capture a much higher percentage of the incoming photons than does film.

Question: Order the following in order of increasing efficiency of detecting photons of visible light.

Answer: eye, photographic film, CCD

Question: Which of the following statements best describes the two principal advantages of telescopes over eyes?

Answer: Telescopes can collect far more light with far better angular resolution.

Question: Currently, the largest optical telescope mirrors have a diameter of?

Answer: 10 meters

Question: What do we mean by the diffraction limit of a telescope?

Answer: It is the best angular resolution the telescope could achieve with perfect optical quality and in the absence of atmospheric distortion.

Question: Which of the following could not be measured by an observation that uses only imaging?

Answer: the rate at which a variable star brightens and dims

Question: Which of the following could not be determined by an observation that uses only spectroscopy?

Answer: the size of a distant galaxy

Question: What is meant by spectral resolution?

Answer: It is a measure of how close two spectral lines can be distinguished