21st Century Astronomy (sixth Edition)
6th Edition
ISBN: 9780393675504
Author: Laura Kay, Stacy Palen, George Blumenthal
Publisher: W. W. Norton & Company
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Question
Chapter 1, Problem 28QP
To determine
Whether the scientist’s statement that it is a known fact that life does not exist beyond Earth is reputable.
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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
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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?
Imagine that we discovered a new planet that has the potential to support
life. This planet has plenty of water on its surface and carbon dioxide in its
atmosphere, and a nice, comfortable temperature similar to Earth. The
only difference is that this planet orbits a star that produces green light
only.
If we took some plants from Earth and planted them on this new planet,
would our plants be able to grow? Explain your answer.
Chapter 1 Solutions
21st Century Astronomy (sixth Edition)
Ch. 1.1 - Prob. 1.1CYUCh. 1.2 - Prob. 1.2CYUCh. 1.3 - Prob. 1.3CYUCh. 1 - Prob. 1QPCh. 1 - Prob. 2QPCh. 1 - Prob. 3QPCh. 1 - Prob. 4QPCh. 1 - Prob. 5QPCh. 1 - Prob. 6QPCh. 1 - Prob. 7QP
Ch. 1 - Prob. 8QPCh. 1 - Prob. 9QPCh. 1 - Prob. 10QPCh. 1 - Prob. 11QPCh. 1 - Prob. 12QPCh. 1 - Prob. 13QPCh. 1 - Prob. 14QPCh. 1 - Prob. 15QPCh. 1 - Prob. 16QPCh. 1 - Prob. 17QPCh. 1 - Prob. 18QPCh. 1 - Prob. 19QPCh. 1 - Prob. 20QPCh. 1 - Prob. 21QPCh. 1 - Prob. 22QPCh. 1 - Prob. 23QPCh. 1 - Prob. 24QPCh. 1 - Prob. 25QPCh. 1 - Prob. 26QPCh. 1 - Prob. 27QPCh. 1 - Prob. 28QPCh. 1 - Prob. 29QPCh. 1 - Prob. 30QPCh. 1 - Prob. 31QPCh. 1 - Prob. 32QPCh. 1 - Prob. 33QPCh. 1 - Prob. 34QPCh. 1 - Prob. 35QPCh. 1 - Prob. 36QPCh. 1 - Prob. 37QPCh. 1 - Prob. 38QPCh. 1 - Prob. 39QPCh. 1 - Prob. 40QPCh. 1 - Prob. 41QPCh. 1 - Prob. 42QPCh. 1 - Prob. 43QPCh. 1 - Prob. 44QPCh. 1 - Prob. 45QP
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