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9 terms

Space

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summer solstice
June 21; longest period of daylight in the year; represents the start of summer
winter solstice
December 21; shortest day of the year; represents the start of winter
equinox
day and night are of equal length
geocentric model
proposed by Aristotle; Earth-centered model of the solar system
heliocentric model
proposed by Copernicus; Sun-centered model of the solar system
Kepler
discovered that orbits of the planets were ellipses and not circles
celestial sphere
imaginary "sphere of sky" surrounding Earth
ecliptic
apparent path of the Sun through the sky during the year
celestial equator
imaginary line around the celestial sphere directly above Earth's equator