ast 180- ch 6 review

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 time on? A a refractor B the telescope with the biggest aperture possible C a telescope with a small aperture but with eyepieces that have good magnification D a telescope built before 1948 E any telescope will show faint galaxies well; they should just use the one closest to their campus

B

The earliest telescopes used by astronomers were: A reflectors B refractors C radio telescopes D about the aperture of the telescope on Mount Palomar E used late at night to look into the neighbors' windows

B

What type of telescope can be used routinely on the surface of the Earth during the DAY? A a visible-light telescope B a radio telescope C an x-ray telescope D a gamma-ray telescope E you can't fool me, there is no telescope that can be used during the DAY

B

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?" A the place must have clear weather on as many nights as possible B the place must be near a university or college C the sky above the place must be dark (no light pollution) D the place must be dry (not too much water vapor in the air) E the air at the place must be quiet, not turbulent

B

Why do astronomers prefer to put infrared telescopes on high-flying airplanes or on satellites in space? A because no infrared radiation can exist anywhere near the Earth's surface B because the water vapor in the lower atmosphere is very good at absorbing infrared C because high up the Sun's energy can be used to heat the infrared telescope D because that way they are significantly closer to the objects they observe E You can't fool me, all infrared telescopes are located on the Earth's surface

B

Radio telescopes of modest size can't make out as much detail (have a lower resolution) than visible light telescopes. How do astronomers overcome this limitation? A they have built a radio telescope in the desert that completely covers 1000 square miles B this problem can't be solved; radio telescopes will always show poor detail C we can connect several radio telescopes some distance apart together electronically to give us the resolution of a larger telescope D we have launched a small radio telescope satellite into orbit, which (being above the atmosphere) can make out much more detail than any visible light telescope E the same engineers responsible for the shape of the mirror for the Hubble Space Telescope are working on this problem; stay tuned

C

The size of the device that collects radiation (such as light) is called a telescope's: A magnification B resolution C aperture D focal width E Galilean criterion

C

To break up light into the component colors that it contains, astronomers use a device called: A a telescope B a CCD C a spectrometer D Cassegrain splitter E interferometer array

C

When the James Webb Space Telescope is finally launched, what will be its distinguishing characteristic (what about it will really help astronomers)? A it will observe gamma-rays from the most energetic events in the universe B it will be the same size and design as the Hubble Space Telescope, which is wearing out C it will have the largest mirror ever put into space for observing faint objects D it will allow us to take pictures with the same resolution as a radio dish E it will be in low Earth orbit, and thus easy for astronauts to repair

C

When the twin Keck telescopes were built in the 1990's, what distinguished them from other very large telescopes of the time? A they were reflectors, while other large telescopes were all refractors B they were on a mountain, while all other telescopes had been built near big cities C they used a mirror assembly that was made of 36 smaller hexagonal mirrors working together D they had a smaller overall aperture, which made it easier to take pictures E they had a motorized drive system to allow the telescope to move smoothly

C

Which of the following is NOT an advantage that the Hubble Space Telescope has over large telescopes on Earth? A the Hubble is above the Earth's atmosphere, while on the ground star images twinkle and jiggle B the Hubble can observe at wavelengths (such as UV) which cannot be seen from the ground C the Hubble has a larger aperture than any visible-light telescope on Earth D the Hubble has a better resolution than visible-light telescopes on Earth (not counting adaptive optics) E you can't fool me, all of these are advantages the Hubble has over earth-bound telescopes

C

Your friend, a graduate student in astronomy, is giving you a special tour of the local observatory. You notice that you are viewing the image from the big telescope from underneath the primary mirror; the beam of light has come through a small hole in the main mirror to an eyepiece below. This telescope uses what focusing arrangement? A prime focus B Newtonian focus C Cassegrain focus D Galilean focus E out of focus

C

At the largest and most modern astronomical observatories on Earth today, which of the following regularly happens to the image formed by the telescope? A it is viewed by a group of graduate students who then make a sketch of it to have a permanent record B it is recorded on a piece of black & white film, which is then developed in a bath of chemicals C it is reflected by a special arrangement of mirrors back into the beam and up into the sky D it is recorded using an electronic detector called a CCD for later analysis E it is sent to the FBI so they can check for evidence of Russian hacking

D

Which of the following has a longer integration time (can collect light for a longer period of time) than the human eye? A photographic film B photographic plates C a CCD (charge coupled device) D all of the above E none of the above

D

Why is an image recorded with a CCD better for astronomers than an image recorded on photographic film or plates? A CCD's are more efficient; more of the light is recorded and not wasted B CCD's allow more accurate measurements of the brightness of each part of the image C CCD's have digital output that can go directly to a computer D all of the above E none of the above

D

In a radio telescope, the role that the mirror plays in visible-light telescopes is played by: A a spectrometer B an interferometer C computer software D a special kind of lens E a large metal dish (antenna)

E

Of the following, which has the highest resolution (ability to make out fine detail): A the German 100-meter radio dish B the 305-meter Arecibo radio dish in Puerto Rico C the 64-meter radio dish near Parkes, Australia D the Very Large Array of radio telescopes in New Mexico E the Very Long Baseline Array of Radio Telescopes, stretching from the Virgin Islands to Hawaii

E