# Flashcards on Mastering Astronomy Chapter 1

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If we represent the solar system on a scale that allows us to walk from the Sun to Pluto in a few minutes, then:
the planets would all be marble size or smaller and the nearest stars would be thousands of miles away.
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What do astronomers mean by the Big Bang?
the event that marked the beginning of the expansion of the universe
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An astronomical unit is
Earth's average distance from the Sun
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Put the following into perspective: the size of our solar system; the distance to nearby stars; the size of the Milky Way Galaxy; the size of the observable universe. Rank from largest to smallest. To rank items as equivalent, overlap them.
The observable universe, The Milky Way Galaxy, Distances to nearby stars, solar system
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Our solar system consists of
the sun and all the objects that orbit it
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On a scale where the Sun is about the size of a grapefruit and the Earth is about 15 meters away, how far away are the nearest stars besides the Sun?
about the distance across the United States
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A television advertisement claiming that a product is light-years ahead of its time does not make sense because
it uses \"light-years\" to talk about time, but a light-year is a unit of distance
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The total number of stars in the observable universe is roughly equivalent to
the number of grains of sand on all the beaches on Earth.
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Which of the following has your \"cosmic address\" in the correct order?
You, Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe
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When we look at an object that is 1,000 light-years away we see it _
as it was 1,000 years ago
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Suppose we look at two distant galaxies: Galaxy 1 is twice as far away as Galaxy 2. In that case
we are seeing Galaxy 1 as it looked at an earlier time in the history of the universe than Galaxy 2
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Could we see a galaxy that is 20 billion light-years away? (Assume that we mean a \"lookback time\" of 20 billion years.)
No, because it would be beyond the bounds of our observable universe.
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Suppose we make a scale model of our solar system, with the Sun the size of a grapefruit. Which of the following best describes what the planets would look like?
The planets are all much smaller than the Sun. Four planets are within about 20 meters of the Sun, while the rest planets are spread much farther apart.
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If you could count stars at a rate of about one per second, how long would it take to count all the stars in the Milky Way Galaxy?
Several thousand years
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The total number of stars in the observable universe is about
the same as the number of grains of sand on all the beaches on Earth
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Using the ideas discussed in your textbook, in what sense are we \"star stuff\"?
Nearly every atom from which we are made was once inside of a star.
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How are galaxies important to our existence?
Galaxies recycle material from one generation of stars to the next, and without this recycling we could not exist.
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If we imagine the history of the universe compressed into one year, dinosaurs became extinct
yesterday morning
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Relative to the age of the universe, how old is our solar system?
It is about one-third the age of the universe.
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How do the speeds at which we are moving with Earth's rotation and orbit compare to the speeds of more familiar objects?
Earth's rotation carries most people around the axis faster than a commercial jet travels, and Earth's orbit carries us around the Sun faster than the Space Shuttle orbits Earth.
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Why do the patterns of the stars in our sky look the same from year to year?
Because the stars in the constellations are so far away.
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Where is our solar system located within the Milky Way Galaxy?
Roughly halfway between the center and the edge of the visible disk of the galaxy
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Astronomers infer that the universe is expanding because distant galaxies all appear to
be moving away from us, with more distant ones moving faster
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Which statement about motion in the universe is not true?
The mysterious dark matter is the fastest-moving material in the universe.
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The star Betelgeuse is about 600 light-years away. If it explodes tonight,
we won't know about it until 600 years from now.
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The fact that nearly all galaxies are moving away from us, with more distant ones moving faster, helped us to conclude that:
The universe is expanding
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What do we mean when we say that the universe is expanding?
Average distances between galaxies are increasing with time.
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If the 14 billion year history of the universe were compressed to one year, and \"now\" is exactly midnight December 31, approximately how long ago were your grandparents born?
0.15 second ago
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What is the \"Raisin Cake model\" intended to explain?
that every raisin in a raisin cake moves farther away from every other raisin: there is no special central raisin (and no special central galaxy)
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Which of the following correctly lists our \"cosmic address\" from small to large?
Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe
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The Earth rotates one a _ on its acis and orbits the Sun once each _ The eliptic plane is the plane defines by _ 's orbit around _. Axis tolt of a planet is the amount that _ is tipped relative to a line perpendicular to the ecliptic plane.
day, year, Earth, the Sun, its axis
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Which of the following best describes what we mean by the universe?
the sum total of all matter and energy
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The term observable universe refers to
that portion of the universe that we can see in principle, given the current age of the universe
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Could we see a galaxy that is 50 billion light-years away?
No, because it would be beyond the bounds of our observable universe.
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The age of our solar system is about: