Download AST 150: Radioactive Dating Game Activity

Name ______________________________________________________
AST 150: Radioactive Dating Game Activity
http://phet.colorado.edu/simulations/sims.php?sim=Radioactive_Dating_Game
Purpose: You will use the radioactive decay rate and original-daughter element ratios of carbon-14
and uranium-238 to determine the ages of different objects.
Procedure:
1. Load PhET Radioactive Dating Game
2. Click on tab for Decay Rates
3. Select Carbon-14. Using the graph,
the estimated half-life for C-14 is
_________ years.
Bucket
Slider
4. Move the bucket slider all the way to
the right. This will place 1000 C-14
atoms onto the screen.
a. Click on the Start/Stop to stop the
C-14 decay. Click on Reset All
Nuclei
Start/Stop
button
Step
button
b. Click on the Start/Stop to start the C-14 decay. Stop the decay as you get close to one halflife.
c. Use the Step button to stop decay at one half-life.
• After 1 half-life, how many C-14 atoms of the 1000 original remain? _______
d. Use the Start/Stop and Step buttons to reach two half-lives. After two half-lives, how many
C-14 atoms remain? ________
• What fraction of C-14 atoms present at 1 half-life remain after 2 half-lives? _______
e. Use the Start/Stop and Step buttons to reach three half-lives. After three half-lives, how
many C-14 atoms remain? ________
• What fraction of C-14 atoms present at 2 half-life remain after 3 half-lives? _______
f. Repeat Steps (a) to (e) with uranium-238.
• Estimated half-life for U-238 is _________ years.
• After 1 half-life, how many U-238 atoms of the 1000 original remain? _______
• What fraction of U-238 atoms present at 1 half-life remain after 2 half-lives? _______
• What fraction of U-238 atoms present at 2 half-life remain after 3 half-lives? _______
g. Based on the results of 4a to 4f, explain the meaning of the word “half-life” in one sentence.
5.
Click on the Measurement tab.
6. Under Probe Type, select Uranium-238 and
Objects. Under Choose an Object, select
Rock.
7. Click on Erupt Volcano. Let the simulation
run until you reach 1 half-life. What % of the
original uranium remains? _________. How
many years did this take? ____________
8. Under Probe Type, select Carbon-14 and
Objects. Under Choose an Object, select
Tree.
9. Click on Plant Tree. Let the simulation run until you reach 1 half-life. What % of the original
carbon remains? _________. How many years did this take? ____________
10. Explain why uranium-238 is used to measure the age of rocks while carbon-14 is used to
measure the age of the tree trunk?
11. Click on Dating Game tab. There are
objects on the surface and in the five
layers beneath the surface. There are both
rocks and fossils in each layer.
12. Select the Carbon-14 detector. Move the
Geiger counter to each fossil and record
the % of original in the table below
13. On the ½ life graph, move the green arrow
right or left until the % of original matches
the reading on the detector. Record your
estimated age for each fossil in the table
14. Repeat Steps 12 and 13 using the Uranium2-38 detector to estimate the rock ages. For fossils
with no remaining C-14 signal, use the rock ages to estimate fossil ages in the same layer.
15. Summarize how C-14 and U-238 dating together can be used to determine fossil ages.
Table:
Radiometric Ages for Various Objects
Object
Animal Skull
Living Tree
Distant Living Tree
House
Dead Tree
Bone
Wooden Cup
1st human skull
2nd human skull
Fish Bones
Fish Fossil 1
Rock 1
Dinosaur Skull
Rock 2
Trilobite
Rock 3
Rock 4
Rock 5
Measured using
C-14 or U-238?
% of
Original
Guessed
Age
Measured
Age
AST 150 Activity: Solar System Properties Overview
Purpose: To develop an understanding of the large-scale patterns which exist within the solar system.
Materials: Graph paper, calculator, color pencils, planetary data.
Procedure: Using the graph paper provided and the data tables that follow, create bar graphs to
represent the following characteristics of the planets. Include Pluto and Eris on your graphs.
Characteristics:
• Mass
• Radius
• Density
• Number of moons
• Inclination of orbit
• Eccentricity of orbit
• Sidereal Rotation Period
• Axis Tilt
Analysis:
Using your graphs as a guideline, group the planets based on similar traits. List your groups on a
separate sheet of paper. You may have as many groups as you like, but each group must contain at
least two planets. For each group, describe the characteristics which separate the planets in the group
from those in other groups. Provide a statistical range for your parameters in each group.
Questions:
Answer on a separate sheet of paper:
1. Often, elementary school science classes learn that there are two types of planets – gas giants
and rocky planets.
a. Are there any planets that don’t seem to fit too well with either of these groups?
b. Do the gas giants all fit together, or is a further division evident?
2. Are there some patterns that are the same for all, or nearly all of the planets, regardless of what
group they’re in? Describe any such patterns.
3. Are there any features of individual planets that stand out as being odd or out of place? If so,
which features?
4. Consider the exoplanets we have studied so far, how many more categories would you need to
add?
diameter
(Earth=1)
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto
Eris
0.382
0.949
1
0.532
11.209
9.44
4.007
3.883
0.180
0.188-0.235
diameter
(km)
mass
(Earth=1)
mean
distance
from Sun
(AU)
orbital
period
(Earth
years)
orbital
eccentricity
mean
orbital
velocity
(km/sec)
rotation
period (in
Earth days)
inclination
of axis
(degrees)
inclination
of orbit
(degrees)
mean
temperature
at surface
(C)
gravity at
equator
(Earth=1)
escape
velocity
(km/sec)
mean
density
(water=1)
atmospheric
composition
number of
moons
rings?
4,878
12,104
12,756
6,787
142,800
120,000
51,118
49,528
2300
2400-3000
0.055
0.815
1
0.107
318
95
15
17
.002
.0028
0.39
0.72
1
1.52
5.20
9.54
19.18
30.06
39.44
67.7
0.24
0.62
1
1.88
11.86
29.46
84.01
164.8
247.7
557
0.2056
0.0068
0.0167
0.0934
0.0483
0.0560
0.0461
0.0097
0.2482
0.44177
47.89
35.03
29.79
24.13
13.06
9.64
6.81
5.43
4.74
3.436
58.65
-243*
1
1.03
0.41
0.44
-0.72*
0.72
-6.38*
?
0.0
177.4
23.45
23.98
3.08
26.73
97.92
28.8
122
?
7
3.39
0
1.85
1.30
2.485
0.772
1.769
17.16
44.187
-180 to
430
465
-89 to
58
-82 to
0
-150
-170
-200
-210
-220
-230
0.38
0.9
1
0.38
2.64
0.93
0.89
1.12
0.06
0.082
4.25
10.36
11.18
5.02
59.54
35.49
21.29
23.71
1.27
1.31
5.43
5.25
5.52
3.93
1.33
0.71
1.24
1.67
2.03
1.18-2.31
none
CO2
N2 +
O2
CO2
H2+He
H2+He
H2+He
H2+He
CH4
CH4
0
0
1
2
63
62
27
13
3
1
no
no
no
no
yes
yes
yes
yes
http://www.windows2universe.org/our_solar_system/planets_table.html
no
No
AST 150: Planet Quest Activity
Name:_____________________
Visit the site http://planetquest.jpl.nasa.gov/index.cfm Answer the following questions: 1. What is the current planet count?
a. Candidates?
b. Confirmed?
2. What is the difference between a candidate planet versus a confirmed planet? (hint click the planet
count)
Click on the New Worlds Atlas link http://planetquest.jpl.nasa.gov/newworldsatlas
3. How many stars have been found to have planets?
4. How many gas giants?
5. How many Hot Jupiters?
6. How many super earths?
7. How many terrestrial (earthlike) planets have been found?
Start with the Planetquest Historic Timeline and Answer the following questions:
http://planetquest.jpl.nasa.gov/system/interactable/2/timeline.html
1. What year did Frank Drake predict extraterrestrial civilizations?
2. What year was the Hubble Space telescope launched?
3. What year was the first extrasolar planet discovered?
4. What was the first multiple planet system discovered?
5. When did the Spitzer space telescope first detect direct light from an exoplanet?
Now select the Interstellar Trip planner
http://planetquest.jpl.nasa.gov/system/interactable/5/index.html
Select three different journeys (destination/vehicle combos) and record your results:
Now select the current news page http://planetquest.jpl.nasa.gov/news
Choose one current news story and write a one paragraph summary:
AST 150 Drake Equation Activity: Is There Life on Other Worlds?
Goals
• To estimate the number of worlds in the Milky Way galaxy that have life
• To think about the size and composition of the galaxy and how that affects the possibility of
extraterrestrial life
• To understand and estimate the terms of the Drake Equation
Background
Hundreds of new planets have been discovered orbiting other stars in the Milky Way galaxy and we
have just begun to explore. Since there are many alien solar systems, the question of whether there is
intelligent life living there becomes more prevalent. It raises many other questions as well. What is
life? How does it begin and evolve on another planet? What conditions can life tolerate? How do we
look for extraterrestrial life?
Do you think there is intelligent life in our galaxy with which we can communicate? In 1961, Dr.
Frank Drake identified eight terms to help people think about what would have to take place for such
communication to be possible.
where:
N = the number of civilizations in our galaxy with which communication might be possible;
and
R* = the average rate of star formation per year in our galaxy
fp = the fraction of those stars that have planets
ne = the average number of planets that can potentially support life per star that has planets
fℓ = the fraction of the above that actually go on to develop life at some point
fi = the fraction of the above that actually go on to develop intelligent life
fc = the fraction of civilizations that develop a technology that releases detectable signs of their
existence into space
L = the length of time such civilizations release detectable signals into space
This is just one attempt to try and quantify the probability of extraterrestrial life. However, each of
these factors has values that are open to interpretation. See what you think the chances are by making
your own estimate for each of the terms below. The conservative and optimistic values indicate the
range of opinion among scientists with regard to each term. You can use the conservative or optimistic
estimates or use another value, depending on your own intuition.
TERM
BACKGROUND
1 The total These numbers are based on observations of the stars in our galaxy, the Milky Way galaxy, and of other galaxies we believe to be like our own. Most scientists believe the number of stars to be 400 billion. number of stars in the Milky Way galaxy Conservative
estimate
Optimistic
estimate
100 billion
600 billion
Your
estimate
2 The percent of stars that are appropriate
3 The percent of these stars that have planetary systems 4 The average number of habitable planets or moons within a solar system 5 The percent of habitable planets or moons that develop life 6 The percent of planets with life that develop intelligent life 7 The percent of intelligent life that develops radio technology 8 The percent of “current” civilizations having radio technologies Many scientists believe that a star has to be like our sun, which is a Main Sequence, G-­‐type star. Only about 5% of the stars in our galaxy are G-­‐type stars, though about 10% are the closely related F-­‐ and K-­‐type stars. About 50% of stars exist in binary or multiple systems, which many scientists feel make them inappropriate. Appropriate stars may not have planets circling them. We have only just begun detecting extra-­‐solar planets, so we don’t really know how common they are. 5%
45%
5%
50 – 100%
Our only example of this term is our own solar system. Could Earth be the only habitable place in our solar system? Is our system typical? Remember that if one system has no habitable planets or moons and another has four, the average would be two per system. 0.1 On average, there is one habitable planet in every ten systems
0.000001% Life is a rare accident that is unlikely to happen elsewhere
4 On average, there are four habitable planets in every system 100% Life will arise if conditions are appropriate
0.0001% or less Only one in a million planets with life will develop intelligent life
0.0001% or less Only one in a million planets with intelligent civilizations will develop radio technology
0.0001% or less One in a million civilizations with radio tech will develop it in time to detect signals from another civilization
100% Any planet with life will develop intelligent life
Having a planet or moon that is appropriate for life doesn’t necessarily mean that life will arise. No real data are available to help us estimate this term. Earth is the only planet on which we know there is life. However, bacterial life existed on Earth shortly (geologically speaking) after its formation, possibly indicating that the development of life is easy. Many scientists believe that whether or not life arises depends on many factors. On Earth, humans developed intelligence, apparently as an evolutionary advantage. However, this term depends on how you define intelligence. Are dolphins, gorillas, octopus, and ants intelligent? Furthermore, single-­‐celled life existed on Earth very early, and multicellular life took 2.5 billion years to form. Maybe the development of complex life, let alone intelligent life, is unusual. Communication with intelligent extraterrestrials requires that we hear from them. Given the vast distances of space, they would probably send signals which travel at the speed of light, such as radio waves. On Earth, humans have only just developed radio technology, so possibly this term should have a low value. But, we did eventually develop radio technology, so maybe this is true of all intelligent beings. Will an extraterrestrial’s signals overlap with the lifespan of the receiving civilization? Extraterrestrials that sent signals a million years ago from a world a million light years away would still overlap with us, even if they died out long ago. So, how long do civilizations with radio technology last? A high level of technological development could bring with it conditions that ultimately threaten the species. Or maybe, once a society has radio technology, it may survive for a long time. Finally, radio signals may give way to more advanced, less noisy technologies such as optical fiber. No one would hear us! 100% All intelligent life will develop radio technology
10% One in a ten civilizations with radio technology will develop it in time to detect signals from another civilization Questions and Analysis
1. To find out your estimate of the number of worlds in the Milky Way galaxy that have intelligent life that
we can detect using radio technology, fill out the Drake Equation worksheet and multiply the eight
terms together. Write your answer here:
2. Based on your estimates, how good are our chances of hearing from intelligent extraterrestrials?
3. How does your answer to Question 2 compare to what you thought before you began the activity?
4. Can your answer to Question 1 be less than one? Why or why not?
5. When making estimates, in which terms did you have the most confidence? The least? Why?
6. Are you more optimistic or conservative when it comes to thinking about extraterrestrial life with radio
technology in the Milky Way galaxy? Why?
7. How could you adjust the estimates in the equation to have it come out so that Earth is the only planet in
the Milky Way galaxy with radio technology?
8. If tomorrow’s newspaper headline read, “Message Received from Outer Space” what would it mean to
you?
9. What would your reaction be if we discovered microbes on another planet? Plants? Insects? Mammals?
Intelligent life?
10. If microbial life were discovered on another planet, what implications might such a discovery have?
11. How would you define extraterrestrial now? How does your current definition differ from the one that
the class developed earlier in the activity?
12. What do you think is the most abundant life form on Earth?
13. If life exists elsewhere, what do you think it will look like?