COSMIC PERSPECTIVE
9th Edition
ISBN: 9780135729458
Author: Bennett
Publisher: PEARSON
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Chapter 24, Problem 55EAP
SETI Signal. Consider a civilization broadcasting a signal with a power of 10,000 watts. The Arecibo radio telescope, which is about 300 meters in diameter, could detect this signal if it was coming from as far away as 100 light-years. Suppose instead that the signal is being broadcast from the other side of the Milky Way Galaxy, about 70,000 light-years away. How large a radio telescope would we need to detect this signal? (Hint: Use the inverse square law for light.)
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In 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.
The Apollo program (not the lunar missions with astronauts) being conducted at the Apache Point Observatory uses a 3.5 - m telescope to direct lasers at retro-reflectors left on the Moon by the Apollo astronauts. the Moon is 384, 472 km away approximately how long do the operators need to wait to see the laser light return to Earth? (Hint: The speed of light is 300,000 km/s.]
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 24 Solutions
COSMIC PERSPECTIVE
Ch. 24 - Prob. 1VSCCh. 24 - Prob. 2VSCCh. 24 - Prob. 3VSCCh. 24 - Prob. 4VSCCh. 24 - Prob. 5VSCCh. 24 - Prob. 6VSCCh. 24 - Prob. 1EAPCh. 24 - Prob. 2EAPCh. 24 - Prob. 3EAPCh. 24 - Prob. 4EAP
Ch. 24 - How are laboratory experiments helping us study...Ch. 24 - Prob. 6EAPCh. 24 - Prob. 7EAPCh. 24 - Prob. 8EAPCh. 24 - Prob. 9EAPCh. 24 - Prob. 10EAPCh. 24 - Prob. 11EAPCh. 24 - Prob. 12EAPCh. 24 - Prob. 13EAPCh. 24 - Prob. 14EAPCh. 24 - Prob. 15EAPCh. 24 - Prob. 16EAPCh. 24 - Prob. 17EAPCh. 24 - For each of the following futuristic scenarios,...Ch. 24 - Prob. 19EAPCh. 24 - Prob. 20EAPCh. 24 - Prob. 21EAPCh. 24 - Prob. 22EAPCh. 24 - Prob. 23EAPCh. 24 - Prob. 24EAPCh. 24 - Prob. 25EAPCh. 24 - Prob. 26EAPCh. 24 - Choose the best answer to each of the following....Ch. 24 - Choose the best answer to each of the following....Ch. 24 - Choose the best answer to each of the following....Ch. 24 - Choose the best answer to each of the following....Ch. 24 - Choose the best answer to each of the following....Ch. 24 - Prob. 32EAPCh. 24 - Choose the best answer to each of the following....Ch. 24 - Prob. 34EAPCh. 24 - Choose the best answer to each of the following....Ch. 24 - Prob. 36EAPCh. 24 - The Turning Point. The end of this chapter...Ch. 24 - Prob. 39EAPCh. 24 - Prob. 43EAPCh. 24 - Prob. 45EAPCh. 24 - Prob. 46EAPCh. 24 - Prob. 47EAPCh. 24 - Prob. 48EAPCh. 24 - Prob. 49EAPCh. 24 - Prob. 50EAPCh. 24 - What’s Wrong with This Picture? Many science...Ch. 24 - Nearest Civilization. Suppose there are 10,000...Ch. 24 - SETI Search. Suppose there are 10,000...Ch. 24 - SETI Signal. Consider a civilization broadcasting...Ch. 24 - Prob. 56EAPCh. 24 - Prob. 57EAP
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Similar questions
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- Tutorial 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_forwardIf you could search for life in the galaxy shown in this image, would you look among stars in the disk, in the central bulge, in the halo, or in all of those places? Discuss the factors that influence your decision.arrow_forwardWould a human have been possible during the first generation of stars that formed right after the Big Bang? Why or why not?arrow_forward
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- If you detected radio signals with an average wavelength of 37 cm and suspected that they came from a civilization on a distant Earth-like exoplanet, roughly how much of a change in wavelength (in cm) should you expect to detect as a result of the orbital motion of the distant exoplanet? (Hint: Use the Doppler shift formula.) (Note: Earth's orbital velocity is 30 km/s.) cmarrow_forwardSuppose that stars were born at random times over the last 1010 years. The rate of star formation is simply the number of stars divided by 1010 years. The fraction of stars with detected extrasolar planets is at least 11 %. The rate of star formation can be multiplied by this fraction to find the rate planet formation. How often (in years) does a planetary system form in our galaxy? Assume the Milky Way contains 3 × 1011 stars.arrow_forwardPlanetary Nebula Age. Suppose a planetary nebula is 1 pc in radius. If the Doppler shifts in its spectrum show it is expanding at 20 km/s, how old is it? (Note that 1 pc equals 3.1x1013 km, and 1 year equals 3.2x107 seconds, to two significant figures.) Please round your answer to two significant digits. At = yearsarrow_forward
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