21ST CENT.ASTRONOMY(LL)W/CODE WKBK PKG.
6th Edition
ISBN: 9780393874921
Author: PALEN
Publisher: Norton, W. W. & Company, Inc.
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Chapter 24.4, Problem 24.4CYU
To determine
The evaluation of Drake equation by the astronomers.
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The 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.
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.)
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.
Chapter 24 Solutions
21ST CENT.ASTRONOMY(LL)W/CODE WKBK PKG.
Ch. 24.1 - Prob. 24.1CYUCh. 24.2 - Prob. 24.2CYUCh. 24.3 - Prob. 24.3ACYUCh. 24.3 - Prob. 24.3BCYUCh. 24.4 - Prob. 24.4CYUCh. 24 - Prob. 1QPCh. 24 - Prob. 2QPCh. 24 - Prob. 3QPCh. 24 - Prob. 4QPCh. 24 - Prob. 5QP
Ch. 24 - Prob. 6QPCh. 24 - Prob. 7QPCh. 24 - Prob. 8QPCh. 24 - Prob. 9QPCh. 24 - Prob. 10QPCh. 24 - Prob. 11QPCh. 24 - Prob. 12QPCh. 24 - Prob. 13QPCh. 24 - Prob. 14QPCh. 24 - Prob. 15QPCh. 24 - Prob. 16QPCh. 24 - Prob. 17QPCh. 24 - Prob. 18QPCh. 24 - Prob. 20QPCh. 24 - Prob. 21QPCh. 24 - Prob. 22QPCh. 24 - Prob. 23QPCh. 24 - Prob. 24QPCh. 24 - Prob. 25QPCh. 24 - Prob. 26QPCh. 24 - Prob. 27QPCh. 24 - Prob. 29QPCh. 24 - Prob. 30QP
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- Why are upper-main-sequence (high-luminosity) host stars unlikely sites for intelligent civilizations?arrow_forwardWhat are the advantages to using radio waves for communication between civilizations that live around different stars? List as many as you can.arrow_forwardThe 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_forward
- 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?)arrow_forwardWhat are the three requirements that scientists believe an environment needs to supply life with in order to be considered habitable?arrow_forwardSuppose 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.arrow_forward
- 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_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_forwardWhich of the following is not considered a likely solution to the question of why we are not currently aware of an extraterrestrial civilization? Group of answer choices There is no civilization because civilizations are not common. The civilization is probably undetectable to us because it makes use of technologies that do not obey the known laws of physics. There is no galactic civilization because civilizations do not leave their home worlds. There is no civilization because most civilizations destroy themselves before achieving interstellar travel. The civilization is deliberately avoiding contact with us.arrow_forward
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