Mastering Astronomy Chapter 16-17 – Flashcards
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Why is dark matter is inferred to exist?
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Because we can observe its gravitational influence on visible matter
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Dark energy has been hypothesized to exist in order to explain what?
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Observations suggesting that the expansion of the universe is accelerating
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The flat part of the Milky Way's rotation curve tells us that stars in the outskirts of the galaxy do what?
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Orbit the galactic center just as fast as stars closer to the center
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What is a likely candidate for the majority of the dark matter in galaxies?
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Subatomic particles that we have not yet detected
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The major evidence for the idea that the expansion of the universe is accelerating comes from the observations of what?
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White dwarf supernoave
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Is the universe hotter or cooler since the Big Bang?
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It is cooler
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What do the laws of thermal radiation tell us about objects and their wavelength?
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Hotter objects emit light with shorter wavelengths (higher energy)
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What important event occurred about 0.001 seconds after the Big Bang?
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Most matter in the early universe was annihilated by antimatter
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What was the first important event to occur in the history of the universe?
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Spacetime rapidly expanded during a brief period of inflation
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During the history of the universe, what event occurred 380,000 years after the Big Bang?
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Light began to travel freely through the universe
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When was the hydrogen nuclei in our universe created?
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By the time our universe was about 3 minutes old
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When were protons formed?
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During the particle era
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How is the cosmic microwave backward now compared to when it was first released?
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Fainter and has most of its photons at longer wavelengths
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If the era is older, is it hotter or cooler than a newer era?
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The older the era, the hotter it is
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Is an older era larger or smaller than a new era?
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Older eras are smaller
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What is the charge of an antiproton?
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Negative
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What happens when a proton collides with an antiproton?
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They convert into two photons
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What is the current temperature of the universe?
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A few degrees
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What does inflation help explain?
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The uniformity of the cosmic microwave background and the origin of galaxies
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What is the best explanation for why the sky is dark?
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Because the universe is not infinite in space
