Read Chapter 6
1.) What is the function of a lens or a curved mirror in a telescope?
2.) How are telescope observations better than "naked eye" observations?
a.) telescopes can collect more light than a human eye can
b.) telescopes can have better angular resolution than a human eye
c.) both of the above
d.) none of the above
3.)
a.) In order to see the features on a planet clearly, do you want
your telescope's
diffraction limit to be smaller than the angular separation between
the features on the planet, or do you want your telescope's diffraction
limit to be larger than the angular separation between features on
the planet
b.) Explain why
4.) Compare a 5 meter telescope with a 10 meter telescope:
a.) Which has the better diffraction limit and by what factor
is it better than the diffraction limit
of the other telescope?
(The wavelength of the light to be observed is 656 nm, but
it is possible for
you to do this problem without knowing the wavelength.)
b.) Which has the larger light collecting area and by what
factor?
5.) Briefly describe the advantages of putting telescopes in space.
6.) Which one of the following could be a true statement
(taken from textbook):
a.) The image was blurry because the photographic film was not placed
at the focal plane
b.) Thanks to adaptive optics, the telescope on Mount Wilson
can now make ultraviolet images of the cosmos
c.) New technologies will soon allow astronomers to use X-ray telescopes
on the Earth's surface
d.) Thanks to interferometry, a properly spaced set of 10-meter radio
telescopes can achieve the
light-collecting area of a single, 100-kilometer radio telescope
e.) All of the above are true
7.) If our eyes don't see radio frequency light, how do astronomers make images of radio emission?
8.) Which one of the following would be an example of a spectroscopic observation? a.) Astrid, the astronomer wanted to study a particular optically thin gas cloud. Unlike the relatively bright Orion Nebula, her cloud was very dim. So, Astrid studied it by recording the light from a star located beyond the gas cloud and measuring how much 410nm, 434nm, 486nm, and 656nm light the gas cloud had absorbed. b.) Astrid, the astronomer wanted to study a particular binary star system. Her binary star system was very far away and so she was not able to resolve the two stars in her photographs. So, Astrid studied it by recording the system's flux every minute over several weeks. She could see that the flux varied in a regular, periodic fashion. c.) Astrid, the astronomer wanted to study the bubbles made by exploding stars. Since her favorite bubble was so faint, she had to put a filter on her telescope. She used a filter that only allowed 656 nm light to come through to the detector. From her observations, she was able to see the circular shape of the bubble. d.) None of the above
9.)
When we look at the night sky, we see that the stars "twinkle".
Why is that?
10.) Which types of light (i.e. which wavelengths) cannot pass easily
through the Earth's atmosphere.