Astronomy
1st Edition
ISBN: 9781938168284
Author: Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher: OpenStax
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Textbook Question
Chapter 30, Problem 29E
Suppose astronomers discover a radio message from a civilization whose planet orbits a star 35 lightyears away. Their message encourages us to send a radio answer, which we decide to do. Suppose our governing bodies take 2 years to decide whether and how to answer. When our answer arrives there, their governing bodies also take two of our years to frame an answer to us. How long after we get their first message can we hope to get their reply to ours? (A question for further thinking: Once communication gets going, should we continue to wait for a reply before we send the next message?)
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Suppose we find an Earth-like planet around one of our nearest stellar neighbors, Alpha Centauri (located only 4.4 light-years away). If we launched a "generation ship" at a constant speed of 1500.00 km/s from Earth with a group of people whose descendants will explore and colonize this planet, how many years before the generation ship reached Alpha Centauri? (Note there are 9.46 ××1012 km in a light-year and 31.6 million seconds in a year.
Read the Blitzer Bonus attached herewith. The future is now: You have the opportunity to explore the cosmos in a starship traveling near the speed of light. The experience will enable you to understand the mysteries of the universe in deeply personal ways, transporting you to unimagined levels of knowing and being. The downside: You return from your two-year journey to a futuristic world in which friends and loved ones are long gone. Do you explore space or stay here on Earth? What are the reasons for your choice?
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Chapter 30 Solutions
Astronomy
Ch. 30 - What is the Copernican principle? Make a list of...Ch. 30 - Where in the solar system (and beyond) have...Ch. 30 - Give a short history of the atoms that are now in...Ch. 30 - What is a biomarker? Give some possible examples...Ch. 30 - Why are Mars and Europa the top targets for the...Ch. 30 - Why is traveling between the stars (by creatures...Ch. 30 - What are the advantages to using radio waves for...Ch. 30 - What is the “cosmic haystack problem”? List as...Ch. 30 - What is a habitable zone?Ch. 30 - Why is the simultaneous detection of methane and...
Ch. 30 - What are two characteristic properties of life...Ch. 30 - What are the three requirements that scientists...Ch. 30 - Can you name five environmental conditions that,...Ch. 30 - Would a human have been possible during the first...Ch. 30 - If we do find life on Mars, what might be some...Ch. 30 - What kind of evidence do you think would convince...Ch. 30 - What are some reasons that more advanced...Ch. 30 - What are some answers to the Fermi paradox? Can...Ch. 30 - Why is there so little evidence of Earth’s...Ch. 30 - Why was the development of photosynthesis a major...Ch. 30 - Does all life on Earth require sunshine?Ch. 30 - Why is life unlikely to be found on the surface of...Ch. 30 - In this chapter, we identify these characteristic...Ch. 30 - Given that no sunlight can penetrate Europa’s ice...Ch. 30 - Why is Saturn’s moon Enceladus such an exciting...Ch. 30 - In addition to an atmosphere dominated by...Ch. 30 - How can a planet’s atmosphere affect the width of...Ch. 30 - Why are we limited to finding life on planets...Ch. 30 - Suppose astronomers discover a radio message from...Ch. 30 - The light a planet receives from the Sun (per...Ch. 30 - Think of our Milky Way Galaxy as a flat disk of...
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