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 4, Problem 3ETQ
To determine
The harder step in the development of intelligent life.
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200 years has passed and now it is year 2220. The Earth is out of basic resourcesas they have been drastically drained in the past 200 years. The president of theUnited World Council (UWC) has approved you and your crew’s Mission toMars. You will pilot the most advanced spaceship the world has ever known, theExcelsior! It will carry equipment that will help to transform Mars so as toresemble the Earth, especially so that it can support human life.Before the mission can launch a few items need to be figured out. What is thecapacity of the fuel tank? How long should the fuel burn to achieve escapevelocity (otherwise the Excelsior will be stuck in the Earth’s gravitational pull)?How long will it take the Excelsior to arrive at Mars?1. The ground crew is filling the fuel tanks. You know th
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?
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 4 Solutions
Loose Leaf For Explorations: Introduction To Astronomy
Ch. 4 - Prob. 1QFRCh. 4 - Prob. 2QFRCh. 4 - Prob. 3QFRCh. 4 - Prob. 4QFRCh. 4 - Prob. 5QFRCh. 4 - Describe the Kelvin temperature scale.Ch. 4 - Prob. 7QFRCh. 4 - Prob. 8QFRCh. 4 - Prob. 9QFRCh. 4 - Prob. 10QFR
Ch. 4 - Prob. 11QFRCh. 4 - Prob. 12QFRCh. 4 - Prob. 1TQCh. 4 - Prob. 2TQCh. 4 - Prob. 3TQCh. 4 - Prob. 4TQCh. 4 - (4.3/4.4/4.5) Given that water absorbs microwaves...Ch. 4 - Prob. 6TQCh. 4 - Prob. 7TQCh. 4 - Prob. 8TQCh. 4 - Prob. 9TQCh. 4 - Prob. 10TQCh. 4 - (4.1) Use the Suns distance of 150 million...Ch. 4 - (4.1) Suppose you are operating a...Ch. 4 - Prob. 3PCh. 4 - Prob. 4PCh. 4 - Prob. 5PCh. 4 - Prob. 6PCh. 4 - Prob. 7PCh. 4 - Prob. 8PCh. 4 - (4. 6) Calculate the Doppler shift for blue light...Ch. 4 - Prob. 10PCh. 4 - (4.2) Which kind of light travels fastest? (a)...Ch. 4 - Prob. 2TYCh. 4 - Prob. 3TYCh. 4 - Prob. 4TYCh. 4 - Prob. 5TYCh. 4 - Prob. 6TYCh. 4 - Prob. 7TYCh. 4 - Prob. 8TYCh. 4 - What is Galilean relativity? Give an example of...Ch. 4 - Prob. 2EQFRCh. 4 - Prob. 3EQFRCh. 4 - Prob. 4EQFRCh. 4 - What is meant by panspermia?Ch. 4 - Prob. 6EQFRCh. 4 - Prob. 7EQFRCh. 4 - Prob. 1ETQCh. 4 - Prob. 2ETQCh. 4 - Prob. 3ETQCh. 4 - Prob. 1EPCh. 4 - Mercury orbits the Sun at speeds ranging from 59...Ch. 4 - Prob. 3EPCh. 4 - Prob. 1ETYCh. 4 - The Miller-Urey experiment demonstrated that (a)...Ch. 4 - Prob. 3ETYCh. 4 - Prob. 4ETYCh. 4 - Prob. 5ETY
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- Tutorial 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_forwardLooking at the speed-time graphs of the four aliens, who shows the greatest rate of slowing down?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
- What is the difference between chemical evolution and biological evolution?arrow_forwardIn this chapter, we identify these characteristic properties of life: life extracts energy from its environment, and has a means of encoding and replicating information in order to make faithful copies of itself. Does this definition fully capture what we think of as “life”? How might our definition be biased by our terrestrial environment?arrow_forwardWhy is life unlikely to be found on the surface of Mars today?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_forwardSuppose 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_forwardWhy is traveling between the stars (by creatures like us) difficult?arrow_forward
- Looking at the speed-time graphs of the four aliens, who shows the greatest rate of speeding up?arrow_forwardWhich of the following seems least reasonable regarding life on Earth? Group of answer choices There is much scientific evidence suggesting that all creatures living on Earth today appear to have evolved from a common ancestor. Louis Pasteur discredited the concept of spontaneous generation by demonstrating that even bacteria and other microorganisms arise from parents resembling themselves. There is ample physical evidence that the earliest life forms on Earth were multicellular creatures, perhaps resembling some of our primitive fish. When the earth formed some 4.6 billion years ago, it was a lifeless, inhospitable place. Before the mid-17th century, most people believed that God had created humankind and other higher organisms and that insects, frogs, and other small creatures could arise spontaneously in mud or decaying matter About billion years into its development, the Earth it was teeming with organisms resembling blue-green algae.arrow_forwardWhich of the following is least reasonable regarding the difficulty in contacting extraterrestrial life using space flight and radio communication. Group of answer choices Space flight to the nearest star would take thousands of years with current technology. Even if another intelligent civilization is within a few hundred light-years of us, conversations would be very slow with a turnaround time of decades or even centuries. The spacecraft that NASA sent to Proxima Centauri a few years ago should be approaching its target within a decade or two, depending on solar wind conditions. Earth has been broadcasting at radio wavelengths since the 1930's, so any civilization within a radius of about 100 light-years or so could have received the broadcast by now. Without some major breakthrough, interstellar space flight is totally impractical.arrow_forward
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