Astronomy Ch 3 – Flashcards
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What does Kepler's third law tell us?
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More distant planets orbit the sun at slower average speeds, obeying a precise mathematical relationship.
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Where was the sun located in Ptolemy's model?
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Between the orbits of Venus and Mars.
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During the Dark Ages in Europe, the scientific work of the ancient Greeks was preserved and further developed primarily by scholars where?
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Baghdad. Scholars working in the Muslim Empire translated and saved many ancient Greek works.
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Which method of weather prediction did the people of Africa use?
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African people learned that the orientation of the crescent of the moon is closely tied to rainfall patterns.
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The Polynesian navigators of the South Pacific found their way primarily by observing the position of Polaris in the night sky.
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False. They used the waves.
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The names of the seven days of the week are based on what?
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After the seven naked-eye objects to move along the constellations.
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How did the Ptolemaic model explain the apparent retrograde motion of the planets?
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Each planet was assumed to move around a small circle that turns upon a larger circle. The resulting path includes a loop in which the planet goes backward as seen from the earth.
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What was the ancient goal of astrology?
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Forecasting human events
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Why was Ptolemy important in the history of astronomy?
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He created and published a model that could correctly predict future planetary positions. His model was used for 1500 years.
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Who developed a system for predicting planetary positions that remained in used for some 1500 years?
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Ptolemy
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Scientific theories can never be proved true beyond all doubt.
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True
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How did Eratosthenes estimate the size of earth in 240 BC?
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He did it by comparing the altitude of the Sun on the summer solstice in the Egyptian cities of Syene and Alexandria.
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What does Kepler's second law tell us?
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As a planet moves around its orbit, it sweeps out equal areas in equal time.
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When and where did the Library of Alexandria exist?
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It existed in 300 BC for some 700 years. In the city of Alexandria.
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Was the Ptolemaic model of the solar system useless for predicting planetary positions?
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No, he created a model that could correctly forecast future planetary positions to within a few degrees of arc.
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Which scientists discovered the principle that we now call Newton's first law of motion?
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Isaac Newton
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What is a hypothesis?
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A tentative model proposed to explain some set of observed facts, but which has not yet been rigorously tested and confirmed.
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Who discovered that the orbits of the planets are ellipses?
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Kepler
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When Copernicus first created his Sun-centered model of the universe, it did not lead to substantially better predictions of planetary motions than the Ptolemaic model. Why not?
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The Ptolemaic model accounted for retrograde motion.
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At the Sun Dagger in New Mexico, a dagger-shaped beam of sunlight pierces a spiral when?
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At noon on the summer solstice
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Copernicus:
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Changed the way we perceive ourselves in the universe
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Tycho:
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Compiled naked-eye observations accurate to within less than one arc minute
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Galileo:
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Built the telescope
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Newton:
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Law of gravity
