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Chapter 3: Question 31
What problem do refractor telescopes have that reflectors don't?
A. bad seeing
B. atmospheric blurring
C. chromatic aberration
D. light loss from secondary elements
E. diffraction limited resolution
- C. Chromatic Aberration
- Chromatic Aberration: when light is separated into its component colors
- Diffraction Limited Resolution: for light, of any given wavelength, large telescopes produce less diffraction than small ones
Chapter 3: Question 30
Which of the following is NOT a reason to use a reflecting telescope rather than a refractor?
A.Heavy lenses, which can only be supported at their edges, tend to deform under their own weight.
B.Lenses absorb light, while mirrors do not.
C.Lenses are harder to focus than mirrors.
D.Lenses are subject to chromatic aberration.
E.A lens must have two precision surfaces; a mirror needs only one.
Chapter 3: Question 11
The light-gathering ability of a telescope is most dependent on the diameter of its primary objective. True or False?
Chapter 3: Question 13
A telescope with an 8-inch mirror will collect twice as much light as one with a 4-inch mirror.
True or False?
Chapter 3: Question 14
The 400" Keck reflector can see objects 100 times fainter than the 40" Yerkes lens. True or False?
Chapter 3: Question 15
Radio telescopes have poorer angular resolution than optical telescopes because radio waves have a much longer wavelength than optical waves. True or False?
Chapter 3: Question 39
What is the resolution of a telescope?
A.its ability to see very faint objects its ability to separate light into its component colors for analysis
B.its ability to make distant objects appear much closer to us
C.its ability to focus more than just visible light for imaging
D.its ability to distinguish two adjacent objects close together in the sky
Chapter 3: Question 42
Green light has a shorter wavelength than orange light. In a 5 inch telescope, green light will...
A.reduce the effects of atmospheric turbulence.
B.provide worse angular resolution than orange light.
C.come to the same exact focus as orange light.
D.provide better angular resolution than orange light.
E.allow dimmer stars to be observed.
Chapter 3: Question 18
The opacity of the atmosphere is partially corrected via adaptive optics. True or False?
Chapter 3: Question 43
What problem does adaptive optics correct?
A.chromatic aberration due to use of only a single lens objective
B.the light pollution of urban areas
C.turbulence in the Earth's atmosphere that creates twinkling
D.defects in the optics of the telescope, such as the original Hubble mirror
E.the opacity of the Earth's atmosphere to some wavelengths of light
(this multiple choice question has been scrambled)
Reflecting Telescopes characterisitics and examples:
- -World's largest telescope
- -Most commonly used by professionals astronomers today
- -Ex: The Hubble Space Telescope
Refracting Telescopes characteristics and examples:
- -Incoming light passes through glass
- -Very large telescopes become "top-heavy"
- -The world's largest is 1-meter in diameter
- -Ex: Galileo's Telescopes
Chapter 3: Question 20
Optical telescopes are usually used only at night, but radio telescopes can be used day or night. True or False?
Chapter 3: Question 21
The Earth's atmosphere is the major factor limiting the use of ground-based radio telescopes. True or False?
Chapter 3: Question 22
Optical interferometry is more in use than radio interferometry. True or False?
Chapter 3: Question 44
What is true of radio telescopes?
A.They are most sensitive to the opacity of the ozone layer.
B.They have better angular resolution than a reflector.
C.They are the smallest, most compact telescopes.
D.They have poorer angular resolution than a refractor of the same size.
E.They can only be used above the atmosphere.
Chapter 3: Question 46
In astronomy, an interferometer can be used to...
A.improve the angular resolution of radio telescopes.
B.increase the sensitivity of infrared telescopes to longer wavelengths.
C.decrease the effects of light pollution in getting darker sky backgrounds.
D.yield better seeing conditions with optical telescopes.
E.speed up the processing of CCD images.
Chapter 3: Question 28
Galaxies look the same whether viewed in visible or X-ray wavelengths. True or False?
Chapter 3: Question 27
The Compton GRO was the first telescope used for our exploration of high-energy astronomy. True or False?
Chapter 3: Question 26
The mirrors for X-ray telescopes are the same shape as those of optical reflectors. True or False?
Chapter 3: Question 25
Due to our ozone layer, ultraviolet astronomy must be done from space. True or False?
Chapter 3: Question 24
Like radio and optical astronomy, infrared astronomy is easily done with ground-based telescopes. True or False?
Chapter 3: Prelecture Question 14
Which of the following regions of the elctromagnetic spectrum is useful for studying distant galaxies?
E.All of the above
Chapter 3: Question 50
Which of the following is currently supplying high resolution X-ray images from space?
Conceptual Self-Test 3.02
The term seeing is used to describe how faint an object can be detected by a telescope. True or False?
Conceptual Self-Test 3.03
One of the primary advantages of CCDs over photographic plates is the former's high efficiency in detecting light. True or False?
Conceptual Self-Test 3.04
Radio telescopes are large in part to improve their angular resolution, which is poor because of the long wavelengths at which they are used to observe the skies. True or False?
Conceptual Self-Test 3.05
Infared astronomy can only be done from space. True or False?
Conceptual Self-Test 3.06
Gamma-ray telescopes employ the same basic design that optical instruments use. True or False?
Conceptual Self-Test 3.07
Because gamma rays have very short wavelengths, gamma-ray telescopes can achieve extremely high angular resolution. True or False?
Conceptual Self-Test 3.08
The main reason that most professional research telescopes are reflectors is that...
A.their images are inverted.
B.they do not suffer from the effects of seeing.
C.large mirrors are easier to build than large lenses.
D.mirrors produce sharper images than lenses do.
Conceptual Self-Test 3.10
The primary reason professional observatories are built on the highest mountaintops is to...
A.improve chromatic aberration.
B.reduce atmospheric blurring.
C.be above the rain clouds.
D.get away from city lights.
Conceptual Self-Test 3.11
When multiple radio telescopes are used for interferometry, resolving power is most improved by...
A.increasing the number of telescopes in a given area.
B.the distance between telescopes.
C.the diameter of each telescope.
D.the electrical power supplied to each telescope.
Conceptual Self-Test 3.12
The Spitzer Space Telescope (SST) is stationed far from Earth because...
A.doing so avoids the obscuring effects of Earth's atmosphere.
B.Earth is a heat source and the telescope must be kept very cool.
C.this increases the telescope's field of view.
D.the telescope is sensitive to electromagnetic interference from terrestrial radio stations
Conceptual Self-Test 3.13
The best way to study young stars hidden behind interstellar dust clouds would be to use...
Conceptual Self-Test 3.14 VIS
Resolution is sharpest when the ratio of wavelengths to telescope size is...
B.close to 1
D.none of these
Conceptual Self-Test 3.15 VIS
The best frequency wave in which to study the hot (million-kelvin) gas found among the galaxies in the Virgo cluster would be...
A.in X rays.
B.in gamma rays.
C.at radio frequencies.
D.in the infrared rays.
Chapter 1: Question 16
In Ptolemy's geocentric model, retrograde motion occurs when the planet is closest to us, on the inside portion of...
Chapter 1: Question 14
In Ptolemy's geocentric model, the planet's motion along its deferent is all that is needed to understand retrograde motion. True or False?
Chapter 1: Question 22
Which of these was NOT seen telescopically by Galileo?
B.Four moons around Jupiter
C.craters and mare on the Moon
D.Venus' phase cycle
Chapter 1: Question 12
Galileo's observations of the entire phase cycle of Venus proved that Ptolemy's epicycles could not be correct in keeping Venus between us and the Sun. True or False?
Vocabulary in Context: Kepler's Planetary Orbits
1. Earth is located at one __ of the Moon's orbit.
2. According to Kepler's second law, Jupiter will be traveling most slowly around the Sun when at __.
3. Earth orbits in the shape of a/an __ around the Sun.
4. The mathematical form of Kepler's third law measures the period in years and the __ in astronomical units (AU).
5. According to Kepler's second law, Pluto will be traveling fastest around the Sun when at __.
6. The extent to which Mars' orbit differs from a perfect circle is called its __.
- 4.Semi-major Axis
- -Aphelion: greatest distance from the Sun
- -Perihelion: point of closest approach to the Sun
- -Eccentricity: how far off an orbit is from an elliptical path
Ranking Task: Kepler's Third Law of Planetary Motion
1. Planets move fastest when they are at the __ (right side).
2. Planets move slowest when they are at the __ (left side).
3. Planetary Orbits go __.
4. Does mass effect orbital periods?
5. Kepler's Third Law formula is __.
- 1. Aphelion
- 2. Perihelion
- 3. Counter-clockwise
- 4. No
- 5. P^2 (in Earth)=A^3 (in AU)
- -P=orbital period
- -A=Semimajor axis
Ranking Task: Kepler's Second Law
1. Kepler's second law states: an imaginary line connecting the Sun to any planet sweeps out __of the ellipse in __.
2. When a planet is ___ to the Sun it moves ___ than when ___ away.
3. When an object is __ to the Sun then, it covers ___ than when it was ___.
- 1. equal areas/ equal intervals of time
- 2. closest/faster/farther
- 3. close/greater distance/farther away
Chapter 1: Question 8
Kepler found the orbits of planets are ellipses, not circles. True or False?
Chapter 1: Question 25
Tycho Brahe's contribution to Kepler's Laws of Planetary Motion were...
A.a precise lunar calendar.
B.a mathematical explanation of epicycles.
C.his detailed and accurate observations of the planets' positions.
D.the correct explanation of lunar phases.
E.his observations of Jupiter's moons.
Chapter 1: Question 3
According to Newton's Second Law, if you double the force acting on a body, the acceleration will double. True or False?