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30 Cards in this Set
- Front
- Back
geocentric |
view that the Earth is at the center of the solar system |
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heliocentric |
view that the sun is at the center of the solar system |
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retrograde motion |
apparent westward movement of the planets with respect to the stars |
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Aristotle |
determined the earth was spherical bc it casts a curved shadow on the moon |
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Eratosthenes |
first successful calculation of the size of the Earth |
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Aristarchus |
Proposed a heliocentric universe. First calculated distance between Earth and sun. First calculated the size of the sun and moon. |
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Nicolaus Copernicus |
Repurposed a heliocentric universe on his deathbed. |
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Tycho Brahe |
made accurate and key observations to disprove a heliocentric universe that ended up proving it |
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Johannes Kepler |
1. Planet orbits are elliptical, not circular 2. Planets speed up and slow down 3. Planets' distance to the sun is proportional to the length go their years |
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Galileo Galilei |
Venus has phases like the moon, proved a heliocentric universe |
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inertia |
property of matter that resists a change in its motion |
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Law of universal gravitation |
every body in the universe attracts every other body with a force that is proportional to their masses and inversely proportional to the square of the distance between them |
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constellation |
apparent group of stars originally named for mythical characters |
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equatorial system |
method of locating stellar objects much like the coordinate system used on Earth's surface |
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declination |
angular distance north or south of the celestial equator denoting the position of a celestial body |
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right ascension |
angular distance measured eastward along the celestial equator from the vernal equinox |
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revolution |
motion of one body about another, such as Earth about the sun |
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axial precession |
slow motion of Earth's axis that traces out a cone over a period of 26,000 years |
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mean solar day |
average time between two passages of the sun across the local celestial meridian |
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sidereal day |
period of rotation with respect to the stars |
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perihelion |
points the orbit of a plane where it is closest to the sun |
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aphelion |
point in the orbit of a planet where it is farthest from the sun |
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ecliptic |
yearly path of Sun plotted against the background of stars |
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plane of ecliptic |
imaginary plane that connects Earth's orbit with the celestial sphere |
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axial precession |
slow motion of Earth's axis that traces out a cone over a period of 26,000 years |
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synodic month |
time period of revolution of the Moon around Earth with respect to the Sun |
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sidereal month |
time period of revolution of the Moon around Earth with respect to the stars |
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phases of the moon |
progression of changes in the Moon's appearance during the month |
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solar eclipse |
eclipse of the Sun |
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lunar eclipse |
eclipse of the Moon |