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Ptolemy states his geocentric theory of the solar system
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He computed the circumference of the earth, the regularity of eclipses of the sun and moon, and how long the earths revolution around the sun is.
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A meteor shower is when meteoroids come in contact with the earth's atmosphere. Meteoroids are small bodies of rock moving through the solar system,
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Ja'far Shakir hypothesizes that celestial bodies are subject to the same physics laws as Earth and suggests that there is a force of attraction between celestial bodies.
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Copernicus states his heliocentric theory of the solar system. Most things revolve around the sun
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Galileo Galilei discovers Jupiter's moons and Saturns rings, disproving part of Ptolemy's theory of the solar system
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The ratio of the squares of the periods of any two planets is equal to the ratio of the cubes of their average distances from the sun.
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Cassini computes how fast Jupiter, Mars, and Venus rotate
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Gravity keeps planets in their orbits. Without it they would be flung into deep space. Centrifugal force is the other factor that keeps planets in their orbits. Without it they would be drawn into the sun.
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Halley predicts the path of Halley's comet and figures out its return path in 1757. A comet is a chunk of rock and ice orbiting the sun. When passing close by the sun, a bright tail appears made of ice and rock coming off of the comet.
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Asteroids are a rocks a few miles across that orbit the sun. Most of them orbit in clusters, between the orbits of Mars and Jupiter.
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It is different from the outer planets because it is terrestrial and hs no rings. The other outer planets have rings and are gaseous and very large. Pluto is more like the inner planets: rocky and small.
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A heliosheath is the region where the solar wind is slowed.
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