Ch. 6

Light gathering power - the light gathering power of a 20-inch reflector is ___ that of a 2-inch refractor.

100 times

Figuring 30 - How much more light can the Keck telescope(with its 10-m diameter mirror) gather than an amateur telescope whose mirror is 25 cm(0.25 m) across?

1600

Figuring 27 - Theoretically(that is, if seeing were not an issue), the resolution of a telescope is inversely proportional to its diameter. Approximately how much better is the resolution of the ALMA when operating at its longest baseline than the resolution of the Arecibo telescope? (Hint: Look up both diameters in the text book.)

50 times better

45. The U.S has plans to build a 30-meter telescope, while the Europeans are thinking about 39-meter telescope. What technological innovation allows astronomers to be thinking about telescopes with that large an aperture?

The mirror in these telescopes will be constructed from many smaller mirrors which will work together

28. What type of telescope can be used routinely on the surface of the Earth during the day?

a radio telescope

10. Which of the following is not an advantage that a reflector telescope has over a refractor telescope?

a reflector doesn't have to deal with the twinkling of the stars, as a refractor does

24. to break up light into the component colors that it contains, astronomers use a device called:

a spectrometer

11. The largest visible-light telescopes in the world use what device to collect as much light as possible before the light is brought to a focus(to act as the light bucket)?

a spectroscope

25. Why is an image recorded with a CCD better for astronomers than an image recorded on photographic film or plates?

all of the above

43. Why do astronomers prefer to put infrared telescopes on high-flying airplanes or on satellites in space?

because the water vapor in the lower atmosphere is very good at absorbing infrared

13. A new technique called adaptive optics allows astronomers to:

compensate for changes in the Earth's atmosphere and achieve better resolution

36. Which of the following is NOT an advantage that the Hubble Space Telescope has over large telescopes on Earth?

the Hubble has a larger aperture than any visible-light telescope on Earth

17. When they build big new(visible - light) telescopes, astronomers want to put them in places where they will get the best views of the sky. Which of the following is not an important part of how astronomers select places for new telescopes?

the place must be near a university or college

9. An astronomer is studying galaxies of stars that are very far away and thus look extremely faint(using visible light). What kind of telescope should she and her graduate students apply for observing time on?

the telescope with the biggest aperture possible

30. Radio telescopes of modest size can't make out as much detail(have poor resolution) than visible light telescopes. How do astronomers overcome this limitation?

we can connect several radio telescopes some distance apart together electronically to give us the resolution of a larger telescope