Astronomy
Astronomy
1st Edition
ISBN: 9781938168284
Author: Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher: OpenStax
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Chapter 2, Problem 43E

Suppose you are on a strange planet and observe, at night, that the stars do not rise and set, but circle parallel to the horizon. Next, you walk in a constant direction for 8000 miles, and at your new location on the planet, you find that all stars rise straight up in the east and set straight down in the west, perpendicular to the horizon. How could you determine the circumference of the planet without any further observations? What is the circumference, in miles, of the planet?

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Chapter 2 Solutions

Astronomy

Ch. 2 - The Sun was once thought to be a planet. Explain...Ch. 2 - Is the ecliptic the same thing as the celestial...Ch. 2 - What is an asterism? Can you name an example?Ch. 2 - Why did Pythagoras believe that Earth should be...Ch. 2 - How did Aristotle deduce that the Sun is farther...Ch. 2 - What are two ways in which Aristotle deduced that...Ch. 2 - How did Hipparchus discover the wobble of Earth’s...Ch. 2 - Why did Ptolemy have to introduce multiple circles...Ch. 2 - Why did Copernicus want to develop a completely...Ch. 2 - What two factors made it difficult, at first, for...Ch. 2 - What phases would Venus show if the geocentric...Ch. 2 - Describe a practical way to determine in which...Ch. 2 - What is a constellation as astronomers define it...Ch. 2 - Draw a picture that explains why Venus goes...Ch. 2 - Show with a simple diagram how the lower parts of...Ch. 2 - Parallaxes of stars were not observed by ancient...Ch. 2 - Why do you think so many people still believe in...Ch. 2 - Consider three cosmological perspectives-the...Ch. 2 - The north celestial pole appears at an altitude...Ch. 2 - What were two arguments or lines of evidence in...Ch. 2 - Although the Copernican system was largely correct...Ch. 2 - During a retrograde loop of Mars, would you expect...Ch. 2 - The Great Pyramid of Giza was constructed nearly...Ch. 2 - Explain why more stars are circumpolar for...Ch. 2 - What is the altitude of the north celestial pole...Ch. 2 - If you were to drive to some city south of your...Ch. 2 - Hipparchus could have warned us that the dates...Ch. 2 - Explain three lines of evidence that argue against...Ch. 2 - What did Galileo discover about the planet Jupiter...Ch. 2 - What did Galileo discover about Venus that cast...Ch. 2 - Suppose Eratosthenes had found that, in...Ch. 2 - Suppose Eratosthenes’ results for Earth’s...Ch. 2 - Suppose you are on a strange planet and observe,...
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