A) Redshifts of galaxies are difficult to measure.
B) The recession velocities of distant galaxies are so great that they are hard to measure.
C) We do not know Hubble's constant very accurately yet.
D) Hubble's law is only useful theoretically;it is difficult to use in practice.
E) The motion of Earth relative to the Milky Way is difficult to account for.
G) A) and C)
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We use established theories fo...View Answer
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A) They are rare events,so we have observed them in only a tiny fraction of all galaxies.
B) We cannot see them beyond a distance of about 100 million light-years.
C) They can occur only in spiral galaxies,not elliptical galaxies.
D) We would,but we don't have enough telescopes.
F) B) and D)
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B) False
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A) spirals only
B) ellipticals only
C) lenticulars only
D) irregulars only
E) all but irregulars
G) C) and D)
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A) the galaxies that are farthest away
B) the galaxies that have the most hot,young O and B stars
C) the galaxies that are the reddest in color
D) the galaxies that are nearest to us
F) A) and C)
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A) Yes,a constant never changes.
B) No,Hubble's constant is roughly equal to 1 divided by the age of the universe,and 10 billion is a substantial enough number to notice a difference.
C) If we went back further in time,it would be different,but 10 billion years is not enough.
D) It would only change if we went 10 billion years into the future.
F) A) and D)
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A) the Milky Way.
B) clusters of galaxies.
C) the observable universe.
D) the Local Group.
F) All of the above
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A) spirals only
B) ellipticals only
C) lenticulars only
D) irregulars only
E) spirals and lenticulars
G) C) and D)
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A) velocity and distance
B) luminosity and distance
C) velocity and temperature
D) luminosity and temperature
E) age and distance
G) None of the above
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B) False
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B) False
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A) the Big Bang
B) all galaxies are moving away from us equally fast
C) the more distant a galaxy is from us,the faster it moves away from us
D) the closer a galaxy is to us,the faster it moves away from us
E) more distant galaxies appear younger
G) A) and E)
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A) A spiral galaxy contains mostly younger stars.
B) A spiral galaxy has a spherical halo.
C) An elliptical galaxy lacks a disk component.
D) Elliptical galaxies are not as big as spiral galaxies.
E) There are no dwarf spiral galaxies,but there are dwarf ellipticals.
G) B) and D)
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A) All white-dwarf supernovae involve the explosion of stars of nearly the same mass.
B) White-dwarf supernovae are so bright that they can be detected even in very distant galaxies.
C) White-dwarf supernovae are common enough that we detect several every year.
D) White-dwarf supernovae occur only among young and extremely bright stars.
E) All white-dwarf supernovae have similar light curves,which makes them easy to distinguish from massive-star supernovae.
G) B) and E)
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A) No,because Hubble did not know the Local Group existed when he discovered his law.
B) No,because galaxies in the Local Group are gravitationally bound together.
C) No,because we do not know the precise value of Hubble's constant.
D) Yes,it works so well that we have never detected any measurable deviations from its predictions.
F) B) and C)
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