Astronomy
1st Edition
ISBN: 9781938168284
Author: Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher: OpenStax
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Textbook Question
Chapter 2, Problem 41E
Suppose Eratosthenes had found that, in Alexandria, at noon on the first day of summer, the line to the Sun makes an angle 30° with the vertical. What, then, would he have found for Earth’s circumference?
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Chapter 2 Solutions
Astronomy
Ch. 2 - From where on Earth could you observe all of the...Ch. 2 - Give four ways to demonstrate that Earth is...Ch. 2 - Explain, according to both geocentric and...Ch. 2 - In what ways did the work of Copernicus and...Ch. 2 - What were four of Galileo’s discoveries that were...Ch. 2 - Explain the origin of the magnitude designation...Ch. 2 - Ursa Minor contains the pole star, Polaris, and...Ch. 2 - How many degrees does the Sun move per day...Ch. 2 - How many degrees does the Moon move per day...Ch. 2 - Explain how the zodiacal constellations are...
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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