Guided Inquiry (6th Our Unique Planet
Purpose: The students will be able to …
Identify several factors that make life anywhere
Discuss why Earth is the only apparent planet in the
solar system capable of supporting life.
Gain an appreciation for how special our planet really is.
Compare and contrast planet features within the solar system.
Use a spreadsheet to analyze planetary data.
Standards Addressed: (Indiana Academic Science Standards)
6.2.2 Use technology, such as calculators or computer spreadsheets, in analysis of
data. (Scientific Thinking)
6.3.1 Compare and contrast the size, composition, and surface features of the
planets that comprise the solar system, as well as the objects orbiting them.
Explain that the planets, except Pluto, move around the sun in nearly
circular orbits. (The Physical Setting)
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. (The Physical Setting)
Access to Microsoft Excel
All of the planets are unique in their composition, size, distance from the sun,
atmosphere, and radius, but there are two general categories that all but one of the
planets fall into. The first category of planets is known as the Terrestrial planets. This
category includes Mercury, Venus, Earth, and Mars. Jupiter, Saturn, Uranus, and
Neptune all belong to the Jovian planet category. Because of its unique size and
composition, Pluto does not fit into either of these two categories. There is even debate
among scientists whether Pluto should be considered a planet. However, when it
comes to life, Earth is in a category of its own. The Earth‟s atmosphere, tilt, revolution,
distance from the Sun, composition, and size are a few of its many features that make
life possible. Several planets may have similar attributes, but none have the necessary
combination for complex life to exist.
There are two planetary attributes that this activity looks at which are necessary
for life support: planetary distance from the sun and the size of the planet. One of the
most basic needs for the support of life on a planet is liquid water on its surface. Water
is the universal solvent necessary for allowing chemical reactions, necessary for life, to
occur. If a planet is too close to the Sun all the liquid water would evaporate. If the
planet is too far from the Sun any possible liquid water would be frozen solid. The
distance away from the host star at which liquid water can exist on a planet‟s surface for
long periods of time is known as the Habitable Zone (Bennet, 251).
Another attribute that makes life possible on Earth is its size. If the Earth was
half of its current size it would not have been able to retain the water vapor and other
gases in its atmosphere necessary for life. The bigger a planet is the stronger the pull of
gravity will be on all of the little particles that compose its atmosphere. If the Earth
was considerably smaller it would not have a strong enough gravitational pull to hold
all the gases in the atmosphere and prevent them from eventually floating off into
Have the students imagine the following scenario:
“Imagine that you live in rural Indiana. The nearest house
is at least a mile away in any direction. The last several
days school has been canceled because it has been
unusualy cold. The night before the temperature dipped
below minus thirty degrees farenheit with the windchill.
You fall asleep with the comforting thought that school
will probably be canceled again the following day because the
temperature is supposed to stay the same. You are awakened in the middle of the night
by what at first seems like your alarm clock, but once you regain consciousness you
realize it is the fire alarm. You can‟t see anything because smoke has already filled the
room and you are having a difficult time breathing. You realize that you must get out
of the house as fast as possible. While crawling toward the window across from your
bed you stumble across your tennis shoes which you decide to quickly put on. As you
open the window you can hear your family calling to you from the front yard for you to
get out of the house. As you crawl out of the window you are releaved to have made it
out of the house alive and to see the rest of your family has also survived. The bitter
cold wind brings you back to reality and you realize that you and your family will not
be able to survive for very long out in this weather. Meanwhile the house is a blazing
inferno. You only have shorts, a t-shirt, and tennis shoes on and your family is dressed
similarly. Fortunately your mother grabbed the cell phone so she could call the fire
department. How are you going to survive in the deadly cold weather until the fire
department shows up?
Interesting Fact: Frostbite can occur in as little as thirty seconds in extreme
Facilitate a discussion about how the students think they would keep warm. Below
are some sample questions which can be used to initiate student thinking.
Is it important how close you stand to the house to stay warm?
Would you want to stand as close as possible or would you want to stand as far
away as possilbe?
How will you keep your entire body warm and prevent frostbite?
The students should come up with the fact that they will have to stand close enough
to the burning house to stay warm but not too close. They should also realize that in
order to keep their entire body warm they would have to rotate their body. They will
have to periodically turn from facing the house to facing away from the house, so one
side of the body will not be exposed to the cold for too long.
Draw the parallel between this example and that of a star and an orbitting planet in
The burning house is like the Sun and you are like the Earth. Just like the fact
that you would need to stand close enough to the house so it would keep you
warm but not too close otherwise you will be burned, a planet needs to be close
enough but not too close to have a suitable temperature for life. Too close and the
planet would be too hot for life, too far away and it would be too cold for life to
exist. The sun is a big burning ball of gas; it is much, much hotter and gives off
much more heat than a burning house, so a planet would need to be far away
from its parent star to have a comfortable temperature, suitable for life.
Space is much colder than even the coldest day in Antarctica. The coldest
temperature ever recorded on Earth was in Vostok, Antarctica on July 21st 1983.
The temperature that day reached -89 ºC. However, this is incomparable to the
temperature of deep space. If you were floating out in space, not exposed to the
sun, your body would reach a temperature below -268 ºC (5K)!!
Also a planet must continue to rotate, otherwise one side would freeze over, and
the other side would become very hot.
Exploration: (The pre-activity discussion is modified from the lesson “Life on
Other Planets” from the Indiana Science Grade 6 Curriculum
Framework, October 2002)
1. Begin by asking the students what kinds of things on Earth make life
possible. What kind of things do organisms on Earth require to survive?
(adequate temperature, water, food/energy (plants, other animals, and the
sun), oxygen to breath, etc…)
2. Ask students: “How do organisms on Earth get their food/energy?”
3. Discuss with students how the sun is the source of energy for almost all
organisms on Earth, plant and animal.
4. Discuss how nothing could survive without the sun, but having a sun is not
enough. A planet must be close enough to the Sun but not too close. Refer
back to the burning house in the engagement discussion (page 2).
5. Ask students: “Have scientists found any signs of life on other planets in the
6. Discuss with students how no known life forms have been found on other
planets, but that scientists continue to look for evidence.
7. Discuss with students that there are many things that are necessary in order
for a planet to be hospitable for life other than the list that was previously
8. Discuss with the students how a planet‟s size affects its ability to hang on to
an atmosphere, which is needed for complex life to exist. This idea is
discussed in further detail in the introduction on page two.
9. Tell the students that they are going to try and design a planet that can
support life. Remind them that these are only two of the many different
things that must be „just right‟ for complex life to exist.
10. Tell the students that as a planet designer they will be able to change how far
the planet is from the Sun and how large it is. Based on these two decisions
the program will tell them if their planet has an adequate temperature for life,
and if it will be able to “hang on” to its atmosphere.
The program is an excel file titled “Our Unique Planet” and can be
downloaded from the P.I.E. Wesite:
The students can input any number into each of the two fields on the
first page of the worksheet (only the yellow colored cells).
This task in not meant to be too easy. This will give the students an
appreciation for how special our planet really is.
11. Once each group finds a set of numbers that would yield a livable planet,
write them up on the board, so the class can compare each set of values.
12. Discuss that there is a range of values that will yield a livable planet, but that
range is very small. Also, mention that the actual temperatures for the
planets vary from the calculated tempertures on the spreadsheet due to the
differences in the planet‟s atmospheres, rotation rates, and other features.
(Eg. The calculated temperature of Venus is around 135ºC, but due to its
atmosphere and internal heating the temperature on the surface of the planet
is around 427ºC.)
1. Have the students click on the “Planetary Data Sheet 1” tab at the bottom of the
excel file. This sheet has planetary distances from the sun and the sizes of each
planet in our solar system.
2. Have the students enter the data for the Earth on the “Planet Design” sheet to
show that the Earth is in the right place in the solar system and is the correct size
3. Have the students enter in the data for the other planets in the solar system, to
see if any of the other planets have a friendly environment to life. The students
should notice that the planets might satisfy one of the criteria for life, but not all.
The students may be surprised that the values for Mars will yield a planet
capable of supporting life. Point these two features are positive for life, but
that there are other features of Mars that do not allow life to exist.
1. Have the students research the other planets in our solar system to find out why
they do not have environments suitable for life, besides unsuitable temperatures.
2. The following websites contain information about the other planets in our solar
system. These websites will allow the students to compare and contrast surface
features, size, and composition of the planets.
a. http://www.nineplanets.org/ (Planet Information)
b. http://www.indianchild.com/know_the_planets.htm (Planet
3. Assign individual planets to each groups of students to research. Have the
students record the gathered information on the Planet Worksheet (page 9).
The excel file, Our Unique Planet.xls, has a table on the worksheet
titled “Planet Data Sheet 2” that compares many different features of
the planets. This can be used as a reference to check student compiled
data on each of the planets. The file also has some additional
information on the planets that might be relevent to the discussion
about planetary differences.
4. Have each of the groups share the gathered information about each planet. Have
each group briefly share about the planet surface features. Next, have each
group briefly share about the size of their planet (each planet‟s relative size
compared to that of Earth is included in “Planet Data Sheet 2” on the excel file).
Lastly, each group should share about planet composition.
5. Have the students generate ideas why the planets they just described might not
be suitable for life. If they have a difficult time thinking of things, ask them why
they would not be able to survive on this or that planet.
6. Show the students the preview for the video “A Privelaged Planet”
This video preview presents more characteristics necessary to support the
development and to sustain the presence of life. Some of the additional
characteristics are included in the Extension section of the lesson.
7. Discuss with the students that when they designed their own planet, they only
looked at two of the many different factors necessary for life to exist, but in
reality there are many!
The video preview may create some student interest in further research
regarding additional characteristics necessary for the development and support of life.
This extension section can be used for students who wish to go beyond what was
discussed and covered in the activity. This is also one of the student assessment
Have the students research other characteristics that can be attributed to the
support of life on Earth. The students can pick from the following list or try to find
other characteristics that make life possible on Earth. Have the students write a
paragraph about each characteristic, including why it is necessary for life and what
would happen if the characteristic was not present. Each student should write about at least
two different characteristics.
Correct location in the galaxy Presence of a large moon
Correct distance from the Sun Plate tectonics
Protected by giant planets Magnetic field
Correct type of star Oxygen rich atmosphere
The following section provides multiple different forms of student assessment.
Students are able to pick between taking a traditional assessment, creating an art
project, writing a newspaper article, or doing additional research and writing a report.
These options allow students to display their current knowledge in different ways
based on their own interests or strengths.
Assessment: **The students have four different options to choose from**
The student assessment could consist of solely the completed Planet Worksheet,
or you may want to use the following suggested questions for further assessment as
part of a quiz or test. These questions were taken directly from the classroom
assessment suggestions for the 6th Grade Indiana State Science Standards.
1. Which of the following is one reason Earth is believed to be the only planet in our
solar system currently capable of supporting life?
A. Earth is the only planet with an atmosphere.
B. Earth is the only planet with gravity.
C. Earth is the only planet with a solid surface.
D. Earth is the only planet with water.
2. Write the letter of the planet next to the correct description.
____smallest planet A Mercury
____closest to the sun B Jupiter
____composed of gas C Pluto
3. Which of the following statements is true? (Circle the best answer)
A. Earth is believed to be the only planet in our solar system currently able to
B. Mars and Earth are believed to be the only planets in the solar system currently
able to support life.
C. All planets are believed to be able to support life.
D. Primitive life forms have been found on the planet Venus.
4. List several different things about the planet Earth that make it unique in its ability to
Answer Key: 1. D; 2. B, A, C; 3. A; 4. See the introduction section on page two.
Visual: (Art Project)
Have the students imagine what it would be like to take a trip to another planet
in our solar system. Based on their knowledge of the planet‟s features, have the
students draw or paint a picture of what they would experience on the surface of the
planet, without a protective space suit or artificial oxygen supply.
Written: (Newspaper Article)
Have the students write a mock newspaper article about the unique
characteristics of the Earth compared to other planet‟s in our solar system. The article
should include several characteristics that make life possible on the Earth and why each
is important for the survival of life as we know it. The reader should come away with
an appreciation for how special our planet really is.
Advanced: (Further Research)
Have the students who choose this option, do what is outlined in the Extension
section on page seven. The students should end up with a short report concerning
additional characteristics necessary for the support of planetary life. Each paragraph
should explain each characteristic, including why it is necessary for life and what would
happen if the characteristic was not present.
1. http://www.nineplanets.org/ (Planet Information)
2. http://www.indianchild.com/know_the_planets.htm (Planet Information)
3. http://www.bbc.co.uk/science/space/solarsystem/ (BBC videos of planet
4. http://www.nasm.si.edu/research/ceps/etp/etp.htm (Images and comparisons
of planetary features)
1. Bennet, Jeffery, Megan Donahue, Nicholas Schneider, Mark Voit. The Essential
Cosmic Perspective. 2nd Ed. Addison Wesley. 2003.
4. Life on Other Planets. Indiana Science Grade 6 Curriculum Framework. Indiana
Department of Education October 2002 p. 101-102.
Author: Aaron Debbink
Names __________________________________________ Period __________________
Planet Surface Features: (What type of things would you find on the surface of the
Planet Size: (How much larger or smaller is this planet than Earth?)
Planet Composition: (What type of things would you find inside of the planet?)