DSST Astronomy

# Of samos was the first astronomer of the alexandrian

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_______________ of Samos was the first astronomer of the Alexandrian school and devised an ingenious method to find the relative distances from the Earth to the sun and moon. Explanation: Aristarchus. His procedure rests on the three assumptions that the moon goes about the Earth in a perfectly circular orbit, that the moon's orbital velocity is perfectly uniform, and that the sun is near enough that its rays travel along diverging paths to different parts of the moon's orbit. Although all three of these assumptions are incorrect, he pioneered a scientific approach that could be used to determine the distances from the Earth to the sun and moon. Aristarchus also devised an ingenious technique to determine the relative ___________ of the sun, moon, and Earth. Detailed Explanation: Sizes. Although the data obtained and used by him were inaccurate and his results somewhat far from the truth, at least they were better than any available before and the first objective measures of astronomical dimensions based on logical reasoning. The table below shows sizes and distances in terms of the Earth's diameter : Aristarchus Modern Moon's distance 10 30 Moon's diameter 1/3 0.272 Sun's distance 200 11,700 Sun's diameter 7 109

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The _________________ hypothesis states that the Earth orbits the sun and the Earth is not the center of the universe. Detailed Explanation: Heliocentric. Aristarchus was the first to profess this belief. This is opposed to the geocentric model of the universe, which states that the Earth is at the center of the universe and all objects revolve around it. Aristotle and Ptolemy were believers in the geocentric model. The greatest astronomer of ancient times was _________________. Detailed Explanation: Hipparchus. His studies are credited with the development of both plane and spherical trigonometry, highly accurate observations, the use of old observations to determine changes, and the invention of a geometrical representation describing the motions of the sun and moon more precisely than ever before. Another Greek astronomer, Cladius ______________, compiled a series of thirteen volumes on astronomy known as the Almagest. Explanation: Ptolemy or Ptolemeus. Most of the Almagest is a compilation of the astronomical achievements of the past, especially Hipparchus. However, it does contain some of his own contributions including the measurement of the distance to the moon by a technique essentially identical to the one used today. Nicolas _______________ was born in Thorn on the Vistula in Poland. His forte was mathematics. Explanation: Copernicus. His great contribution to science was a critical reappraisal of the existing theories of cosmology and the development of a new model of the solar system. Copernicus's excellence as a mathematician and astronomer gave him the information to determine values for the distances of the various ____________ from the sun.
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