Astronomy 101 Chapter 5 and 6 – Flashcards
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What is image processing?
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Computer processing of electronic images to correct for defects and remove noise
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Which of the following is an advantage the Hubble Space Telescope has over ground-based telescopes?
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There is no blurring due to the atmosphere.
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What is the main reason that ultraviolet astronomy must be done in space?
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Earth's atmosphere absorbs most ultraviolet wavelengths.
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What is meant in astronomy by the phrase "active optics"?
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Rapid modifications are made to the tilt and location of the elements of a telescope to correct for the effects of atmospheric and instrumental distortion.
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Which design is subject to chromatic aberration?
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refractor
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Why are most large telescopes reflectors, not refractors?
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Reflectors do not suffer from chromatic aberration like refractors do.
Large mirrors need only one optical surface, achromats four surfaces to grind.
Large, very clear lenses are harder to cast than more tolerant mirror blanks.
Large lenses deform under their own weight, but mirrors can be supported.
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What is the resolution of a telescope?
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its ability to distinguish two adjacent objects close together in the sky
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What is the light-gathering power of an 8-inch telescope compared to a 4-inch telescope?
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4× better
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Diffraction is the tendency of light to:
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spread around corners.
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Refractor telescopes suffer from this separation of light into its component colors.
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chromatic aberration
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A mountain top is an especially good site for infrared telescopes since:
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less air above means better seeing in many cases.
the cold weather helps the sensitivity of infrared detectors.
there you are closer to celestial objects.
you are above most of the carbon dioxide and water vapor in the atmosphere.
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What problem does adaptive optics correct?
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turbulence in the Earth's atmosphere which creates twinkling
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Which of the following is NOT a difference between the operation of a radio telescope and that of an optical reflecting telescope?
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Optical reflectors have their detector placed at the prime focus, whereas radio telescopes do not.
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Chromatic aberration in lenses is a result of which wave property of light?
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Refraction
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How do scientists use the gravitational slingshot effect to send space probes out into space?
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They launch the space probes around other planets to use their gravity to alter the speed and direction of the probes.
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Which of the following is NOT a way in which the terrestrial and jovian planets differ?
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The jovian planets have orbits that are highly inclined to the ecliptic and do not revolve in the same direction as the terrestrial planets.
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Which of the following is NOT a characteristic of terrestrial planets?
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Lower density than jovian planets
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Why is dust important to the condensation sequence?
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Without dust, there would be nothing for the solar nebula gas to condense onto.
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In light of modern solar system theory, why do the orbits of the planets all lie near the same plane?
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The early solar nebula flattened into a disk.
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What property of the early solar nebula resulted in the high degree of differentiation among the planets?
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Temperature gradient
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Where in the solar system does the asteroid belt lie?
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Between the orbits of Mars and Jupiter
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Which of the major planets listed below has the highest mass?
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Saturn
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Which of the following objects are composed of material mostly unchanged since the formation of the solar system?
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Comets and asteroids
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What is the composition of comets?
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Icy with dust
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Planetesimals were created through what process?
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accretion
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What is the primary reason that the jovian planets contain so much more volatile liquid and gaseous material than the terrestrial planets?
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They orbited at sufficiently greater distances from the Sun that these volatile materials were ices and liquids that were easier to accumulate.
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What theory do astronomers use to rectify the apparent problem of insufficient time to form jovian planets?
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the gravitational instability theory
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What class of objects has been observed, lying just beyond the orbit of Neptune and roughly in the plane of the solar system that lends additional credence to the condensation hypothesis for planetary system formation?
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Kuiper belt objects
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Which of these bodies has the lowest density?
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a comet
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Mercury's most unusual orbital feature, as compared to the other planets, is:
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the shape of its orbit.
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Which characteristic listed below describes the jovian planets?
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low density
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Which of the characteristics below describes the terrestrial planets?
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possessing weak magnetic fields
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In composition and density, the asteroids most resemble:
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pieces of terrestrial planets.
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The Kuiper Belt is found where in the solar system?
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beyond the orbit of Neptune
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What happens when a solar nebula contracts?
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It flattens out.
It spins faster.
It heats up.
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Conservation of angular momentum means that a spinning body tends to:
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keep spinning.
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What was the primary role of dust in the formation of the solar system?
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Dust acted as condensation nuclei; platforms to which other particles could attach and form larger particles of matter.
