Astro 1001 Chapter 6 Questions
The light-collecting area of an 8-meter telescope is _____ times that of a 2-meter telescope.
16
How much greater is the light-collecting area of a 6-meter telescope than a 3-meter telescope?
Four times
Which of the following best describes why radio telescopes are generally much larger in size than telescopes designed to collect visible light?
Getting an image of the same angular resolution requires a much larger telescope for radio waves than for visible light.
Where should you put a telescope designed for ultraviolet observations?
In earth orbit
What do we mean by the diffraction limit of a telescope?
It is the angular resolution the telescope could achieve if nothing besides the size of its light-collecting area affected the quality of its images.
Which of the following best describes what we mean by the focal plane of a telescope?
It is the place where, if we mounted film or an electronic detector, we could get a clear (not blurry) image of an object viewed through the telescope.
Can the Hubble Space Telescope resolve the two stars?
No
Choose the correct statement describing, what will you see if you look at them with a telescope that has an angular resolution of 0.5 arcsecond.
One point of light that is the blurred image of both stars.
The angular separation of two stars is 0.1 arcseconds and you photograph them with a telescope that has an angular resolution of 1 arcsecond. What will you see?
The photo will seem to show only one star rather than two.
Why are astronomers interested in building observatories capable of detecting neutrinos, cosmic rays, and gravitational waves?
These things are not forms of light, and therefore can provide different types of information than light about objects that emit them.
Why can't X-ray and gamma-ray telescopes use the same designs as visible-light telescopes?
X rays and gamma rays have so much energy that they cannot be reflected in the same way as visible light.
The Hubble Space Telescope obtains higher-resolution images than most ground-based telescopes because it is:
above Earth's atmosphere.
Now remember that humans have two eyes that are approximately 7 centimeters apart. Estimate the diffraction limit for human vision, assuming that your "optical interferometer" is just as good as one eyeball as large as the separation of two regular eyeballs.
θ2-eye=1.8''
What is the angular separation of the two stars? Give your answer in degrees.
θ=2.7×10^6
What is the angular separation of the two stars? Give your answer in arcseconds.
θ=9.7×10−3′′ ″
How does this compare to the diffraction limit of a 10-meter telescope?
θeye/θtelescope=1300
Calculate the diffraction limit of the human eye, assuming a wide-open pupil so that your eye acts like a lens with diameter 0.8 centimeter, for visible light of 500-nanometer wavelength.
θeye=16″
