Mindtap Astronomy, 1 Term (6 Months) Printed Access Card For Seeds/backman's Foundations Of Astronomy, 14th
14th Edition
ISBN: 9781337399975
Author: Michael A. Seeds, Dana Backman
Publisher: Cengage Learning
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Chapter 25, Problem 10P
To determine
The number of communicative civilization per galaxy.
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A radio broadcast left Earth in 1911. 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 0.20. How many possible planets with life could have heard this signal?
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.
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…
Chapter 25 Solutions
Mindtap Astronomy, 1 Term (6 Months) Printed Access Card For Seeds/backman's Foundations Of Astronomy, 14th
Ch. 25 - Explain how astrobiology is a science and not a...Ch. 25 - Describe one special quality of water that makes...Ch. 25 - Mars and Europa are two Solar System bodies that...Ch. 25 - How does the DNA molecule produce a copy of...Ch. 25 - What would happen to a life-form if the genetic...Ch. 25 - What would happen to a life-form if the genetic...Ch. 25 - What would happen to a life-form if the...Ch. 25 - Describe an example of natural selection acting on...Ch. 25 - Prob. 9RQCh. 25 - What evidence do scientists have that life on...
Ch. 25 - Define organic, as in organic molecule. How is...Ch. 25 - Why is liquid water generally considered necessary...Ch. 25 - Some meteorites contain organic molecules. What...Ch. 25 - What is the difference between chemical evolution...Ch. 25 - Prob. 15RQCh. 25 - Why was Earths early atmosphere able to support...Ch. 25 - Molecules of which gas were needed in Earths...Ch. 25 - Does intelligence make a creature more likely to...Ch. 25 - Describe one hypothesis for how cells first...Ch. 25 - What is the evidence that the first organisms on...Ch. 25 - Name three locations in our Solar System to search...Ch. 25 - Why are upper-main-sequence (high-luminosity) host...Ch. 25 - Prob. 23RQCh. 25 - How does the stability of technological...Ch. 25 - Prob. 25RQCh. 25 - Prob. 26RQCh. 25 - Why are scientists confident Earth has never been...Ch. 25 - Why does the Drake equation implicitly assume the...Ch. 25 - A single human cell encloses about 1.5 m of DNA....Ch. 25 - If you represent Earths history by a line that is...Ch. 25 - Consider Figure 25-8. What is the ratio of the...Ch. 25 - Suppose a human generation is defined as the...Ch. 25 - If a star must remain on the main sequence for at...Ch. 25 - Prob. 6PCh. 25 - If you detected radio signals with an average...Ch. 25 - Prob. 8PCh. 25 - The first radio broadcast was made on January 13,...Ch. 25 - Prob. 10PCh. 25 - The DNA in a single cell in your body contains...Ch. 25 - Prob. 2SOPCh. 25 - Look at Figure 25-11. Since the time we sent the...Ch. 25 - The star cluster shown in this image contains a...Ch. 25 - If you could search for life in the galaxy shown...
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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
- Consider Figure 25-8. What is the ratio of the length of time since the origin of fish to the time since the origin of mammals? What does this value indicate?arrow_forwardCalculate the numb of communicative civilizations per galaxy using your n estimates of the factors in Table 20-1.arrow_forwardWhat is the difference between chemical evolution and biological evolution?arrow_forward
- What are the advantages to using radio waves for communication between civilizations that live around different stars? List as many as you can.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_forwardThe Drake equation tells us that the number of technological civilizations in our Galaxy at this time is: Group of answer choices About 100,000. About 14 billion. About 200 billion. It cannot predict this number at this time. About 6,000. About 1 million. Somewhere in the range 1-10.arrow_forward
- The Drake equation attempts to calculate the number of communicative civilizations in the galaxy. What does the factor F S represent and why is it considered to be the most uncertain of all the factors in this equation?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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