COSMIC PERSPECTIVE
9th Edition
ISBN: 9780135729458
Author: Bennett
Publisher: PEARSON
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Chapter 16, Problem 51EAP
To determine
To Write:A report about molecules found in space.
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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…
25. When Mars is 90 million km from Earth, a) How long would it take for a radio wave from a video camera mounted on the back of a Mars Rover to tell ground control on earth that the Rover is about to go over a cliff? b) How long would it take for a radio signal from Earth to reach the Rover saying "STOP". c) Why do our Mars Rovers have to be "intelligent" enough to figure out how to deal with obstacles themselves?
18 If we develop spacecraft that can take humans to nearby solar systems at a few percent of the speed of light, how long would it be before we could conceivably populate all
habitable planets in the entire Milky Way?
A
B
D
E
A few hundred thousand years
A few hundreds of millions of years
We could never colonize the galaxy unless we had ships that could travel very close to the speed of light.
A few million years
A few billion years
Chapter 16 Solutions
COSMIC PERSPECTIVE
Ch. 16 - Prob. 1VSCCh. 16 - Prob. 2VSCCh. 16 - Prob. 3VSCCh. 16 - Prob. 4VSCCh. 16 - Prob. 1EAPCh. 16 - Prob. 2EAPCh. 16 - Prob. 3EAPCh. 16 - Prob. 4EAPCh. 16 - Prob. 5EAPCh. 16 - Prob. 6EAP
Ch. 16 - Prob. 7EAPCh. 16 - Prob. 8EAPCh. 16 - Prob. 9EAPCh. 16 - Prob. 10EAPCh. 16 - Prob. 11EAPCh. 16 - Prob. 12EAPCh. 16 - Prob. 13EAPCh. 16 - Prob. 14EAPCh. 16 - Prob. 15EAPCh. 16 - Prob. 16EAPCh. 16 - Prob. 17EAPCh. 16 - Prob. 18EAPCh. 16 - Prob. 19EAPCh. 16 - Prob. 20EAPCh. 16 - Prob. 21EAPCh. 16 - Prob. 22EAPCh. 16 - Prob. 23EAPCh. 16 - Prob. 24EAPCh. 16 - Prob. 25EAPCh. 16 - Prob. 26EAPCh. 16 - Prob. 27EAPCh. 16 - Prob. 28EAPCh. 16 - Prob. 29EAPCh. 16 - Prob. 30EAPCh. 16 - Prob. 31EAPCh. 16 - Prob. 32EAPCh. 16 - Prob. 33EAPCh. 16 - Prob. 34EAPCh. 16 - Prob. 35EAPCh. 16 - Prob. 37EAPCh. 16 - Prob. 38EAPCh. 16 - Prob. 39EAPCh. 16 - Prob. 40EAPCh. 16 - Prob. 41EAPCh. 16 - Prob. 42EAPCh. 16 - Prob. 43EAPCh. 16 - Prob. 44EAPCh. 16 - Prob. 45EAPCh. 16 - Prob. 46EAPCh. 16 - Prob. 47EAPCh. 16 - Prob. 48EAPCh. 16 - Prob. 49EAPCh. 16 - Prob. 50EAPCh. 16 - Prob. 51EAPCh. 16 - Prob. 52EAPCh. 16 - Prob. 53EAPCh. 16 - Prob. 54EAPCh. 16 - Prob. 55EAPCh. 16 - Internal Temperature of the Sun. The Sun is...Ch. 16 - Prob. 57EAPCh. 16 - Angular Momentum of a Close Binary. Some close...Ch. 16 - Prob. 59EAP
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