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32 Cards in this Set
- Front
- Back
Geocentrism
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The interpretation that the universe is earth-centered.
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Our solar system
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The sun and all the objects that orbit it |
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Galaxy
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"a great island of stars in space, containing from a few hundred million to a trillion or more stars"
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Milky Way
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Our galaxy, a large galaxy containing more than 100 billion stars. Member of the LOCAL GROUP
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Galaxy clusters
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Groups of galaxies with more than a few dozen members
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Universe
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the sum total of all matter and energy, encompassing the superclusters and voids and everything within them.
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Is the universe expanding, contracting, or staying the same?
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Expanding
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Big Bang
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Start of expansion of the universe, approx 14 billion years ago
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Birth of our solar system
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4.5 billion years ago
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The only two chemical elements in the early universe
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Hydrogen and helium
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Gravity
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Force that causes gas and dust to form stars and planets
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Nuclear fusion
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The beginning of a star, gravity compresses a material in the cloud to the point where the center becomes dense and hot enough to generate energy from nuclear fusion - the process in which lightweight atomic nuclei smash together to make heavier nuclei
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Supernovae
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An explosion signifying the death of a star
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Star
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A large glowing ball of gas that generates heat and light through nuclear fusion in its core--such as our sun
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Planet
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A moderately large object that orbits a star and shines primarily by reflecting light from its star. Three modern conditions 1: orbits a star, 2: is large enough for its own gravity to make it round 3: has cleared most other objects from orbital path.
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moon
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An object that orbits a planet
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Asteroid
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Small and rocky object that orbits a star.
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Comet
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Relatively small and ice-rich object that orbits a star.
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Supercluster
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Gigantic region of space where many individual galaxies and many groups and clusters of galaxies are packed more closely together than elsewhere in the universe.
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Light-year
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the DISTANCE that light can travel in 1 year, which is about 9.46 trillion kilometers.
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Rotation
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The spinning of an object around its axis
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Orbit (revolution)
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The orbital motion of one object around another
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Observable universe
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the Portion of the entire universe that we can potentially observe--things that lie within 14 billion light-year of earth.
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Great Red Spot
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Storm on Jupiter's surface
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How many stars in the Milky Way
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100 Billion
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Cosmic calendar
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analogizing the history of the universe into 1 year, with big bang at january 1 etc.
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Direction that earth rotates
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West to east--counterclockwise as viewed from above the north pole.
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Astronomical unit (AU)
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Earth's average orbital distance
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Ecliptic plane
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Earth's orbital path, a flat plane
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Earth's axis tilt
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23 and 1/2 from a line perpendicular to the ecliptic plane. Oriented so the earth points almost directly at a star called Polaris, or the North Star.
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Local solar neighborhood
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the region of the sun and nearby stars
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Copernican revolution
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The discovery that earth is not the center of the universe but rather just one planet orbiting the sun.
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