Loose Leaf For Explorations: Introduction To Astronomy
9th Edition
ISBN: 9781260432145
Author: Thomas T Arny, Stephen E Schneider Professor
Publisher: McGraw-Hill Education
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Chapter 18, Problem 5ETY
To determine
The claiming that supports the argument that we are the only civilization in the Milky Way.
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Most of the stars we can see with the unaided eye in our night sky are hundreds or even thousands of lightyears away from Earth. (The very closest ones are only a few dozen lightyears away, but most are much further.) The vast majority of stars in our galaxy are many tens of thousands of lightyears away. IF intelligent life existed on planets orbiting some of these stars – and that’s a huge IF! – comment on the likelihood and practicality of (a) visiting, (b) communicating with, or (c) verifying the existence of those life forms. Describe how you might go about approaching EACH of these three tasks, or if you think they are even possible. (One or two sentences for each part would be appropriate.)
Suppose there are l0,000 civilizations broadcasting radio signals in the Milky Way GaIaxy right now. On average, how many stars would we have to search before we would expect to hear a signal? Assume there are 500 billion stars in the galaxy. How would the answer change if there were only 100 civilizations instead of 10,000?
Suppose there are 9000.0 civilizations broadcasting radio signals in the Milky Way Galaxy at the moment. On average, how many stars would have to be searched before a signal is heard? Assume that there are 8 × 1011 stars in the Galaxy and one civilization per star.
Chapter 18 Solutions
Loose Leaf For Explorations: Introduction To Astronomy
Ch. 18 - Why do astronomers think that the Universe is...Ch. 18 - What is meant by the age of the Universe? How old...Ch. 18 - Prob. 3QFRCh. 18 - What is Olbers paradox?Ch. 18 - Prob. 5QFRCh. 18 - Prob. 6QFRCh. 18 - Prob. 7QFRCh. 18 - Prob. 8QFRCh. 18 - Prob. 9QFRCh. 18 - Prob. 10QFR
Ch. 18 - Prob. 11QFRCh. 18 - Prob. 12QFRCh. 18 - Prob. 13QFRCh. 18 - Prob. 14QFRCh. 18 - Prob. 15QFRCh. 18 - Prob. 16QFRCh. 18 - Prob. 17QFRCh. 18 - Prob. 18QFRCh. 18 - Prob. 19QFRCh. 18 - Prob. 20QFRCh. 18 - Prob. 1TQCh. 18 - Prob. 2TQCh. 18 - Prob. 3TQCh. 18 - Prob. 4TQCh. 18 - Prob. 5TQCh. 18 - Prob. 6TQCh. 18 - Prob. 7TQCh. 18 - Why are there points below the green line (instead...Ch. 18 - Prob. 9TQCh. 18 - Until recently, experimental results for the...Ch. 18 - The temperature of Universe at recombination was...Ch. 18 - Prob. 3PCh. 18 - Prob. 4PCh. 18 - The temperature of the Universe at recombination...Ch. 18 - One second after the Big Bang, the density of the...Ch. 18 - Prob. 7PCh. 18 - Prob. 8PCh. 18 - Prob. 1TYCh. 18 - Prob. 2TYCh. 18 - Prob. 3TYCh. 18 - Which of the following statements about the first...Ch. 18 - Prob. 5TYCh. 18 - Prob. 6TYCh. 18 - Prob. 7TYCh. 18 - Prob. 8TYCh. 18 - Prob. 9TYCh. 18 - Prob. 1EQFRCh. 18 - Prob. 2EQFRCh. 18 - Prob. 3EQFRCh. 18 - Prob. 4EQFRCh. 18 - Prob. 5EQFRCh. 18 - Prob. 6EQFRCh. 18 - Prob. 7EQFRCh. 18 - Prob. 8EQFRCh. 18 - Prob. 9EQFRCh. 18 - What is meant by the Gaia hypothesis?Ch. 18 - Prob. 11EQFRCh. 18 - Prob. 1ETQCh. 18 - Prob. 2ETQCh. 18 - Prob. 3ETQCh. 18 - Prob. 4ETQCh. 18 - Prob. 5ETQCh. 18 - Prob. 6ETQCh. 18 - Prob. 7ETQCh. 18 - Prob. 8ETQCh. 18 - Prob. 1EPCh. 18 - Prob. 2EPCh. 18 - Prob. 3EPCh. 18 - Prob. 4EPCh. 18 - Prob. 5EPCh. 18 - Prob. 6EPCh. 18 - Prob. 1ETYCh. 18 - Prob. 2ETYCh. 18 - Prob. 3ETYCh. 18 - Prob. 4ETYCh. 18 - Prob. 5ETYCh. 18 - Prob. 6ETYCh. 18 - Prob. 7ETY
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- Would a human have been possible during the first generation of stars that formed right after the Big Bang? Why or why not?arrow_forwardThink of our Milky Way Galaxy as a flat disk of diameter 100,000 light-years. Suppose we are one of 1000 civilizations, randomly distributed through the disk, interested in communicating via radio waves. How far away would the nearest such civilization be from us (on average)?arrow_forwardIn a globular cluster, astronomers (someday) discover a star with the same mass as our Sun, but consisting entirely of hydrogen and helium. Is this star a good place to point our SETI antennas and search for radio signals from an advanced civilization? Group of answer choices No, because such a star (and any planets around it) would not have the heavier elements (carbon, nitrogen, oxygen, etc.) that we believe are necessary to start life as we know it. Yes, because globular clusters are among the closest star clusters to us, so that they would be easy to search for radio signals. Yes, because we have already found radio signals from another civilization living near a star in a globular cluster. No, because such a star would most likely not have a stable (main-sequence) stage that is long enough for a technological civilization to develop. Yes, because such a star is probably old and a technological civilization will have had a long time to evolve and develop there.arrow_forward
- TRUE OR FALSE: According to an optimistic evaluation of Frank Drake’s equation, there can be as many as ten thousand technologically communicative civilizations in our Milky Way galaxy alone.arrow_forwardTutorial A radio broadcast left Earth in 1925. How far in light years has it traveled? If there is, on average, 1 star system per 400 cubic light years, how many star systems has this broadcast reached? Assume that the fraction of these star systems that have planets is 0.30 and that, in a given planetary system, the average number of planets that have orbited in the habitable zone for 4 billion years is 0.85. How many possible planets with life could have heard this signal? Part 1 of 3 To figure out how many light years a signal has traveled we need to know how long since the signal left Earth. If the signal left in 1925, distance in light years = time since broadcast left Earth. d = tnow - tbroadcast d = light years Submit Skip (you cannot come back)arrow_forwardTutorial A radio broadcast left Earth in 1923. How far in light years has it traveled? If there is, on average, 1 star system per 400 cubic light years, how many star systems has this broadcast reached? Assume that the fraction of these star systems that have planets is 0.50 and that, in a given planetary system, the average number of planets that have orbited in the habitable zone for 4 billion years is 0.40. How many possible planets with life could have heard this signal? Part 1 of 3 To figure out how many light years a signal has traveled we need to know how long since the signal left Earth. If the signal left in 1923, distance in light years = time since broadcast left Earth. d = tnow - broadcast d = 97 97 light years Part 2 of 3 Since the radio signal travels in all directions, it expanded as a sphere with a radius equal to the distance it has traveled so far. To determine the number of star systems this signal has reached, we need to determine the volume of that sphere. V, = Vb…arrow_forward
- I don’t understand how that it was estimated as length of a mouse is 4 to 15 cm in length. Is that a guess and the answer just varies?also where did 10^-1 come fromarrow_forwardWhat are the advantages to using radio waves for communication between civilizations that live around different stars? List as many as you can.arrow_forwardWhy is traveling between the stars (by creatures like us) difficult?arrow_forward
- Why are we limited to finding life on planets orbiting other stars to situations where the biosphere has created planet-scale changes?arrow_forwardWhat are some answers to the Fermi paradox? Can you think of some that are not discussed in this chapter?arrow_forwardWhat are some reasons that more advanced civilizations might want to send out messages to other star systems?arrow_forward
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