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Part 2: Build Your Own Planet
Lesson 1: The Sun’s Habitable Zone
Time: approximately 40 - 50 minutes
Materials: Text: Lesson 1 – Determining Our Sun’s Habitable Zone (from web site - 1
per group)
Habitable Zone Table (included with students’ Lesson 1 - 1 per group)
Overview
This lesson introduces the Planet Temperature Calculator, which
determines the approximate average surface temperature of a planet based on
values for different physical properties entered by the user. Students will use this
program to find out how the distance from the Sun affects the Earth’s average
surface temperature. Students then graph the effects of changes in distance on
average surface temperatures using Microsoft Excel. The graph is relatively
straightforward, and students without access to Excel can make the graphs by
hand.
Purpose
The purpose of this lesson is to introduce the idea of the “habitable zone.”
The habitable zone is the distance from a star that an object needs to be in order to
maintain a surface temperature that will allow water on the surface to stay in a
liquid state. If a planet is too close to a star the surface will get too hot and water
will boil away. If it is too far away it will get too cold and water will freeze.
Standards
A complete list of the standards covered by this lesson is included in
Appendix A at the end of the lesson.
Procedure
Students should get in their groups with their folders. Each group will need
access to the Planet Temperature Calculator, which is available over the World
Wide Web at: www.astro.indiana.edu/~gsimonel/temperature1.html. As a class
review the introduction to the lesson:
In this lesson we will determine our Sun’s “habitable zone.” The
habitable zone is the distance from the Sun that the Earth can be and
still support life on its surface. Remember that all life that we know of
requires liquid water to survive. Therefore, we can define our habitable
zone as the range of distances from the Sun where the Earth’s average
surface temperature is greater than 0ºC (the melting point of water) but
less than 100ºC (the boiling point). To find out where this area is we will
use the Planet Temperature Calculator. This program figures out the
average surface temperature of a planet based on information about
that planet that you enter.
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The Planet Temperature Calculator looks at the MASS of the star
that your planet is orbiting, the DISTANCE from that star, the BOND
ALBEDO (al-BEE-do) of the planet and the GREENHOUSE EFFECT of the
planet’s atmosphere. In the last lesson we said that increasing the MASS
of a star increases the energy that it gives off (and reduces its life span).
In later lessons we will look at the effects of BOND ALBEDO and
GREENHOUSE EFFECT on temperature. Today we will see how the
DISTANCE from the nearest star affects the temperature. We will enter
Earth-like values for MASS, BOND ALBEDO and GREENHOUSE EFFECT,
enter different values for DISTANCE, and record our results.
The Planet Temperature Calculator is easy to use. Groups should enter
different values for DISTANCE and record the calculated temperatures on their
Habitable Zone Tables.
1) Open the planet temperature program:
www.astro.indiana.edu/~gsimonel/temperature1.html
2) Read the information on this screen and then click on the “continue”
button. This will bring you to the MASS screen. Read the information
about MASS and then , in the white box below the text, enter the
number 1 and click the “next” button next to the box.
3) This will bring you to the DISTANCE screen. Read the information
about DISTANCE, enter the number 1 in the white box, and click the
“next” button.
4) This will bring you to the BOND ALBEDO screen. Read about BOND
ALBEDO, enter the number 29, and click the “next” button.
5) You should be at the GREENHOUSE EFFECT screen now. Read about
the GREENHOUSE EFFECT and enter the number 1 in the box. Then
click the “next” button.
6) This brings you to the “REVIEW” page. You can change any of the
values that you entered on this screen. Don’t make any changes yet, just
click on the button marked “calculate” in the bottom right corner of the
screen.
7) This page tells you what the average surface temperature of your
planet is based on the numbers that you entered. If you entered the
numbers correctly you will see that the Earth has an average surface
temperature of 15 ºC or 59 ºF. You will also see, in the white box toward
the center of the screen, that our Sun has a life cycle of 10 billion years.
That means that our Sun has enough fuel to last 10 billion years. Since
the Sun is around 4.7 billion years old, that means it will last for another
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5.3 billion years before it uses up all its nuclear fuel and dies in a violent
explosion.
Fill out the Habitable Zone Table.
8) Click the “return” button to go back to the REVIEW screen. Do not
change the values for MASS, BOND ALBEDO or GREENHOUSE EFFECT.
Use the Habitable Zone Table to find out what values to enter for
DISTANCE. Start by entering 0.1 for DISTANCE and click the CALCULATE
button. Record the SURFACE TEMPERATURE in degrees Celsius on the
table in the box next to “0.1” Be sure to record the temperature in
degrees Celsius. This is the number in the middle of the three stacked
boxes.
9) Click the RETURN button. Enter 0.2 for DISTANCE and click the
CALCULATE button. Record the SURFACE TEMPERATURE in degrees
Celsius on the table in the box next to “0.2” Click the RETURN button.
10) Continue finding and recording the SURFACE TEMPERATURE for
the rest of the numbers on the table.
Next students will graph their findings in Microsoft Excel. The X-axis will
display the distance from the Sun, and the Y-axis will represent the average
surface temperature.
Making graphs in Microsoft Excel is generally very easy, but some
procedures, like setting the values of your X-axis, are much less obvious than they
could be. Teachers might want to work through this next section beforehand if
possible.
Make a chart in Microsoft Excel.
11) Start Microsoft Excel. Open a new file. In column A, enter “0.1” in
space A1, “0.2” in space A2, etc., down to “1.3” in space A13. In column
B, enter the temperatures from the Habitable Zone Table. Enter the first
temperature in space B1, the second temperature in space B2, etc.
12) On the menu bar, click on Insert>>Chart (or click on the Chart icon).
This opens up the Chart Wizard box.
13) Select the Line chart and click Next.
14) Click on the Data Range tab at the top of the Chart Wizard and then
click on the little data icon on the far right side of the white box in the
middle of the Wizard, next to the space marked Data Range. Click and
drag your cursor over spaces B1 through B13, and hit Enter. (Do not
click Next yet.)
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15) Now click on the Series tab. At the bottom of the box is a space
marked Category (X) axis labels. Click on the data icon to the right of this
space. Click and drag your cursor over spaces A1 through A13, and hit
Enter. Click Next.
16) Click on the Titles tab. For the Chart title: type the name of your
group and then “The Sun’s Habitable Zone.” For Category (X) axis: type
“Distance in Astronomical Units (AU).” For Value (Y) axis: type
“Temperature in Degrees Celsius.” (Do not click Next yet.)
17) Click on the Gridlines tab. For Category (X) axis select “Minor
gridlines.” Check to make sure the “Major gridlines” is selected for Value
(Y) axis. (Do not click Next yet.)
18) Click on the legend tab. De-select “Show legend” by clicking on the
box next to “Show legend” so that the checkmark disappears. Click on
Next.
19) For Place chart: select “As new sheet.” Click Finish. Print your chart.
20) At Earth’s normal atmospheric pressure, water freezes at 0ºCelsius
(C) and boils at 100ºC. The Sun’s habitable zone is the distance from the
Sun where a planet’s average surface temperature is between 0ºC &
100ºC. On your chart, find the point where the line of the graph crosses
the horizontal line for 100ºC, and then check how far out on the X axis
(Distance in AU) this is. This is the inner limit of the Sun’s habitable zone.
Next find the point where the line of the graph crosses the horizontal
line for 0ºC, then check how far out on the X axis this point is. This is the
outer limit.
21) Our Sun’s habitable zone inner limit is ______AU. If the Earth was
any closer to the Sun than this the liquid water on its surface would boil
away.
The Sun’s habitable zone outer limit is ______AU. If the Earth was any
farther away from the Sun than this the liquid water on its surface
would freeze.
If the Earth was outside of this habitable zone, chances are that life as
we know it would not be able to survive at the surface.
Groups should keep their graphs, tables and worksheets in the group
folders.
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Appendix A
Standards Addressed
Benchmarks (Grades 3 through 5)
2A – Patterns and Relationships
Mathematical ideas can be represented concretely, graphically, and symbolically.
2C – Mathematical Inquiry
Numbers and shapes-and operations on them-help to describe and predict things about
the world around us.
4D – Structure of Matter
Heating and cooling cause changes in the properties of materials. Many kinds of changes
occur faster under hotter conditions.
5D – Interdependence of Life
For any particular environment, some kinds of plants and animals survive well, some
survive less well, and some cannot survive at all.
9B – Symbolic Relationship
Tables and graphs can show how values of one quantity are related to values of another.
11B – Models
Seeing how a model works after changes are made to it may suggest how the real thing
would work if the same were done to it.
11C – Constancy and Change
Things change in steady, repetitive, or irregular ways-or sometimes in more than one
way at the same time. Often the best way to tell which kinds of change are happening is
to make a table or graph of measurements.
12A – Values and Attitudes
Keep records of their investigations and observations and not change the records later.
12D – Communication Skills
Use numerical data in describing and comparing objects and events.
Benchmarks (Grades 6 through 8)
2B – Mathematics, Science and Technology
Mathematics is helpful in almost every kind of human endeavor-from laying bricks to
prescribing medicine or drawing a face. In particular, mathematics has contributed to
progress in science and technology for thousands of years and still continues to do so.
4E – Energy Transformation
Most of what goes on in the universe-from exploding stars and biological growth to the
operation of machines and the motion of people-involves some form of energy being
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transformed into another. Energy in the form of heat is almost always one of the products
of an energy transformation.
Heat can be transferred through materials by the collisions of atoms or across space by
radiation. If the material is fluid, currents will be set up in it that aid the transfer of heat.
9B – Symbolic Relationship
Graphs can show a variety of possible relationships between two variables. As one
variable increases uniformly, the other may do one of the following: increase or decrease
steadily, increase or decrease faster and faster, get closer and closer to some limiting
value, reach some intermediate maximum or minimum, alternately increase and decrease
indefinitely, increase or decrease in steps, or do something different from any of these.
11B – Models
Models are often used to think about processes that happen too slowly, too quickly, or on
too small a scale to observe directly, or that are too vast to be changed deliberately, or
that are potentially dangerous.
Mathematical models can be displayed on a computer and then modified to see what
happens.
11D – Scale
As the complexity of any system increases, gaining an understanding of it depends
increasingly on summaries, such as averages and ranges, and on descriptions of typical
examples of that system.
12D – Communication Skills
Organize information in simple tables and graphs and identify relationships they reveal.
Read simple tables and graphs produced by others and describe in words what they
show.
Benchmarks (Grades 9 through 12)
1B – Scientific Inquiry
Sometimes, scientists can control conditions in order to obtain evidence. When that is not
possible for practical or ethical reasons, they try to observe as wide a range of natural
occurrences as possible to be able to discern patterns.
2B – Mathematics, Science and Technology
Mathematical modeling aids in technological design by simulating how a proposed
system would theoretically behave.
Mathematics provides a precise language for science and technology-to describe objects
and events, to characterize relationships between variables, and to argue logically.
4A – The Universe
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Mathematical models and computer simulations are used in studying evidence from many
sources in order to form a scientific account of the universe.
4B – The Earth
Life is adapted to conditions on the earth, including the force of gravity that enables the
planet to retain an adequate atmosphere, and an intensity of radiation from the sun that
allows water to cycle between liquid and vapor.
9B – Symbolic Relationship
Any mathematical model, graphic or algebraic, is limited in how well it can represent
how the world works. The usefulness of a mathematical model for predicting may be
limited by uncertainties in measurements, by neglect of some important influences, or by
requiring too much computation.
Tables, graphs, and symbols are alternative ways of representing data and relationships
that can be translated from one to another.
11B – Models
The basic idea of mathematical modeling is to find a mathematical relationship that
behaves in the same ways as the objects or processes under investigation. A
mathematical model may give insight about how something really works or may fit
observations very well without any intuitive meaning.
Computers have greatly improved the power and use of mathematical models by
performing computations that are very long, very complicated, or repetitive. Therefore
computers can show the consequences of applying complex rules or of changing the
rules. The graphic capabilities of computers make them useful in the design and testing of
devices and structures and in the simulation of complicated processes.
11C – Constancy and Change
Graphs and equations are useful (and often equivalent) ways for depicting and analyzing
patterns of change.
12B – Computation and Estimation
Use computer spreadsheet, graphing, and database programs to assist in quantitative
analysis.
12C – Manipulation and Observation
Learn quickly the proper use of new instruments by following instructions in manuals or
by taking instructions from an experienced user.
Use computers for producing tables and graphs and for making spreadsheet calculations.
12E – Critical-Response Skills
Check graphs to see that they do not misrepresent results by using inappropriate scales
or by failing to specify the axes clearly.
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National Standards (Grades 5-8)
Transfer of Energy
The sun is a major source of energy for changes on the earth's surface. The sun loses
energy by emitting light. A tiny fraction of that light reaches the earth, transferring
energy from the sun to the earth. The sun's energy arrives as light with a range of
wavelengths, consisting of visible light, infrared, and ultraviolet radiation.
Earth in the Solar System
The earth is the third planet from the sun in a system that includes the moon, the sun,
eight other planets and their moons, and smaller objects, such as asteroids and comets.
The sun, an average star, is the central and largest body in the solar system.
National Standards (Grades 9-12)
Understandings about Scientific Inquiry
Scientists rely on technology to enhance the gathering and manipulation of data. New
techniques and tools provide new evidence to guide inquiry and new methods to gather
data, thereby contributing to the advance of science. The accuracy and precision of the
data, and therefore the quality of the exploration, depends on the technology used.
Matter, Energy, and Organization in Living Systems
The energy for life primarily derives from the sun. Plants capture energy by absorbing
light and using it to form strong (covalent) chemical bonds between the atoms of carboncontaining (organic) molecules. These molecules can be used to assemble larger
molecules with biological activity (including proteins, DNA, sugars, and fats). In
addition, the energy stored in bonds between the atoms (chemical energy) can be used as
sources of energy for life processes.
Energy in the Earth System
Earth systems have internal and external sources of energy, both of which create heat.
The sun is the major external source of energy. Two primary sources of internal energy
are the decay of radioactive isotopes and the gravitational energy from the earth's
original formation.
Global climate is determined by energy transfer from the sun at and near the earth's
surface. This energy transfer is influenced by dynamic processes such as cloud cover and
the earth's rotation, and static conditions such as the position of mountain ranges and
oceans.
Indiana Standards
Grade 5
English/Language Arts – Structural Features of Informational and Technical
Materials
5.2.1 – Use the features of informational texts, such as formats, graphics, diagrams,
illustrations, charts, maps, and organization, to find information and support
understanding.
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Mathematics – Problem Solving
5.7.1 – Analyze problems by identifying relationships, telling relevant from irrelevant
information, sequencing and prioritizing information, and observing patterns.
Science – Communication Skills
5.2.7 – Read and follow step-by-step instructions when learning new procedures.
The Universe
5.3.2 – Observe and describe that stars are like the sun, some being smaller and some
being larger, but they are so far away that they look like points of light.
The Earth and the Processes that Shape It
5.3.4 – Investigate that when liquid water disappears it turns into a gas (vapor) mixed
into the air and can reappear as a liquid when cooled or as a solid if cooled below the
freezing point of water.
Matter and Energy
5.3.8 – Investigate, observe, and describe that heating and cooling cause changes in the
properties of materials, such as water turning into steam by boiling and water turning
into ice by freezing. Notice that many kinds of changes occur faster at higher
temperatures.
Systems
5.6.1 – Recognize and describe that systems contain objects as well as processes that
interact with each other.
Grade 6
English/Language Arts – Comprehension and Analysis of Grade-LevelAppropriate Text
6.2.5 – Follow multiple-step instructions for preparing applications.
Mathematics – Number Sense
6.1.1 – Understand and apply the basic concept of negative numbers (e.g., on a number
line, in counting, in temperature, in “owing”).
Algebra and Functions
6.3.9 – Investigate how a change in one variable relates to a change in a second
variable.
Problem Solving
6.7.1 – Analyze problems by identifying relationships, telling relevant from irrelevant
information, identifying missing information, sequencing and prioritizing information,
and observing patterns.
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6.7.8 – Use graphing to estimate solutions and check the estimates with analytic
approaches.
Science – The Scientific Enterprise
6.1.6 – Explain that computers have become invaluable in science because they speed up
and extend people’s ability to collect, store, compile, and analyze data; prepare research
reports; and share data and ideas with investigators all over the world.
Technology and Science
6.1.7 – Explain that technology is essential to science for such purposes as access to
outer space and other remote locations, sample collection and treatment, measurement,
data collection and storage, computation, and communication of information.
Computation and Estimation
6.2.2 – Use technology, such as calculators or computer spreadsheets, in analysis of
data.
Communication Skills
6.2.5 – Organize information in simple tables and graphs and identify relationships they
reveal. Use tables and graphs as examples of evidence for explanations when writing
essays or writing about lab work, fieldwork, etc.
6.2.6 – Read simple tables and graphs produced by others and describe in words what
they show.
The Earth and the Processes that Shape It
6.3.4 – Explain that we live on a planet which appears at present to be the only body in
the solar system capable of supporting life.
Matter and Energy
6.3.17 – Recognize and describe that energy is a property of many objects and is
associated with heat, light, electricity, mechanical motion, and sound.
Interdependence of Life and Evolution
6.4.10 – Describe how life on Earth depends on energy from the sun.
Shapes and Symbolic Relationships
6.5.4 – Demonstrate how graphs may help to show patterns — such as trends, varying
rates of change, gaps, or clusters — which can be used to make predictions.
Models and Scale
6.7.2 – Use models to illustrate processes that happen too slowly, too quickly, or on too
small a scale to observe directly, or are too vast to be changed deliberately, or are
potentially dangerous.
Grade 7
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Mathematics – Algebra and Functions
7.3.9 – Identify functions as linear or nonlinear and examine their characteristics in
tables, graphs, and equations.
Data Analysis and Probability
7.6.1 – Analyze, interpret, and display data in appropriate bar, line, and circle graphs
and stem-and-leaf plots and justify the choice of display.
Problem Solving
7.7.1 – Analyze problems by identifying relationships, telling relevant from irrelevant
information, identifying missing information, sequencing and prioritizing information,
and observing patterns.
7.7.9 – Use graphing to estimate solutions and check the estimates with analytic
approaches.
Science – Communication Skills
7.2.7 – Incorporate circle charts, bar and line graphs, diagrams, scatterplots, and
symbols into writing, such as lab or research reports, to serve as evidence for claims
and/or conclusions.
Matter and Energy
7.3.14 – Explain that energy in the form of heat is almost always one of the products of
an energy trans-formation, such as in the examples of exploding stars, biological growth,
the operation of machines, and the motion of people.
Grade 8
Mathematics – Algebra and Functions
8.3.8 – Demonstrate an understanding of the relationships among tables, equations,
verbal expressions, and graphs of linear functions.
Problem Solving
8.7.1 – Analyze problems by identifying relationships, telling relevant from irrelevant
information, identifying missing information, sequencing and prioritizing information,
and observing patterns.
8.7.9 – Use graphing to estimate solutions and check the estimates with analytic
approaches.
Science – Manipulation and Observation
8.2.4 – Use technological devices, such as calculators and computers, to perform
calculations.
The Physical Setting
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8.3.14 – Describe how heat can be transferred through materials by the collision of
atoms, or across space by radiation, or if the material is fluid, by convection currents
that are set up in it that aid the transfer of heat.
Shapes and Symbolic Relationships
8.5.3 – Demonstrate that mathematical statements can be used to describe how one
quantity changes when another changes.
8.5.4 – Illustrate how graphs can show a variety of possible relationships between two
variables
Models and Scale
8.7.3 – Use technology to assist in graphing and with simulations that compute and
display results of changing factors in models.
Earth and Space Science
The Universe
ES.1.3 – Compare and contrast the differences in size, temperature, and age between our
sun and other stars.
ES.1.5 – Understand and explain the relationship between planetary systems, stars,
multiple-star systems, star clusters, galaxies, and galactic groups in the universe.
ES.1.8 – Discuss the role of sophisticated technology, such as telescopes, computers,
space probes, and particle accelerators, in making computer simulations and
mathematical models in order to form a scientific account of the universe.
The Earth
ES.1.10 – Recognize and describe that earth sciences address planet-wide interacting
systems, including the oceans, the air, the solid earth, and life on Earth, as well as
interactions with the Solar System.
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Appendix B
Copy of Habitable Zone Table (included with lesson)
Distance from Sun, in
Astronomical Units (AU)
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
Average Surface Temperature, in Degrees Celsius