The solar system is immense -- so large that it cannot be easily and accurately reflected in a single image showing any degree of detail about the planets. The numbers we use to describe distances in the solar system (such as 93 million miles, which is the distance from the Earth to the Sun) are so large that few people can comprehend them. Careful construction of a scale model of each planet, then positioning them at scaled distances away from each other on a school ground, will help students understand the vast size of space, and will counter the misconceptions fostered by common representations of the solar system.
Begin this activity by discussing the concept of scale. Discuss the usefulness of models as representations of objects that are either too large to easily fit into the classroom, or too small for our unaided eyes to detect important features. Comparing a toy car to a real car, and figuring out the scale at which the toy was produced, may be a good introduction to this topic.
Before creating the planets, measure the school or playground space in which you will install your model. If you wish to create visible planet models to the same scale, several city blocks may be required. Calculate what scale of Sun you will have to use to fit all or most of the planets in this space. If space is limited, consider placing the outermost planets off school grounds, where they can be visited by bus or a short walking field trip, or placing the planets in a slightly curved line around the edge of a field.
Before using this solar system scale calculator, have your students estimate what size the Sun and planets will need to be to fit their scaled orbits within your schoolyard. This calculator allows you to enter the desired size of your model Sun, then it calculates the scaled diameters for all the planets and their orbits. Enter the students' estimates, then adjust the size of the Sun until your model will fit within your school's space.
Calculating the scaled planet sizes and orbital distances can also be done as math practice, using the table below. First calculate your scaling factor by dividing the largest usable playground distance by the longest measurement that will have to fit in your model: Pluto's distance from the Sun.
Scaling factor = playground length (in meters) / Pluto's distance from the Sun (5,870,000,000 kilometers)
Then multiply this scaling factor by each planet's distance from the Sun, and each planet's diameter. You may decide that your space is too small to make scale models of the planets, or make the planets to a different scale.
| Distance from Sun (kilometers) |
Scale distance from Sun (meters) |
Diameter (kilometers) |
Scale Diameter (meters) |
|
Sun |
0 | 0 | 1,390,000 | |
Mercury |
57,900,000 | 4,879 | ||
Venus |
108,200,000 | 12,104 | ||
Earth |
149,600,000 | 12,756 | ||
Mars |
227,900,000 | 6,794 | ||
Jupiter |
778,600,000 | 142,984 | ||
Saturn |
1,433,500,000 | 120,536 | ||
Uranus |
2,872,500,000 | 51,118 | ||
Neptune |
4,497,100,000 | 49,528 | ||
Pluto |
5,870,000,000 | 2,390 |
Construct models of the Sun and the nine planets. The models can be images on paper or three dimensional representations, but make the scaled size and color as accurate as possible. Small planets may need to be placed on a contrasting background so that they can be viewed at a distance. A small description of the planet, with some important facts about each, could be placed on a sign below each model.
The models can be manipulated to help students discover planetary trends and patterns for themselves. For example, place the planets in order by size. How does this compare to their order from the Sun? Is there a gradual change in size between smallest and largest, or are there distinct size groups? Divide the planets into groups base on their planetary composition, or atmospheric composition. Do planets with similar composition have other similar characteristics? Does color seem to be related to composition? Is color related to order from the Sun, or size?
As a class, place the planets at their scaled distances from the Sun. Do you see any pattern to their placement, such as increasing interplanetary distance as the planets get farther from the Sun? Where does the asteroid belt go? (Most of the asteroids in the solar system are in the asteroid belt between Mars and Jupiter.) Where do you think the comets would fit in this model? (Clouds of comets have been theorized to extend from about the orbit of Pluto, which is 39 times as far from the Sun as Earth, to 100,000 times the distance between the Sun and the Earth. They are dark chunks of ice until they approach the inner reaches of the solar system, near the planets. Here heat from the Sun forms their magnificent tails.)
If students have also been researching the planets, take a walking tour of your solar system, and allow each group to present when their planet is reached.
Even a scale model like this creates another misconception. Because the planets have been arranged in a straight line out from the Sun, many students may believe that they always appear in line in the solar system. This is never the case. For a view of the Solar System as it looks today, visit space.jpl.nasa.gov/. Select this viewpoint and target: show me Solar System as seen from above. Set the desired date and time. In field of view, select 30 degrees to see the orbits of the outer planets clearly, and 5 degrees to see the orbits of Jupiter and the inner planets. Selecting the box beside planet orbits will make it easier to see their relative distances from each other and the Sun.
spacelink.nasa.gov/Instructional.Materials/Curriculum.Support/Space.Science/Our.Solar.System/Charting.The.Planets/Charting.the.Planets Charting the Planets is an Educational Publication of the National Aeronautics and Space Administration. It encourage students in middle and high school to practice reading and interpreting a chart of planetary data, detecting patterns and cycles in the solar system.
spacelink.nasa.gov/Instructional.Materials/On-line.Educational.Activities/Planets/index.html Spacelink: Those Whirling, Twirling Planets is written for elementary school children learning the names, order, diameters, and simple characteristics of the planets.
www.jpl.nasa.gov/ice_fire//outreach/pdf_lib/au1.2.pdf A.U.! Over There! Is an activity guide about measuring the scale of the solar system using relative distances, focusing on interplanetary distances measured in Astronomical Units. This guide is available free for download in PDF format.
lyra.colorado.edu/sbo/mary/Scale/ Make a scale model solar system, Saturn system, and comet. Includes teacher guides and student handouts.
www.nthelp.com/eer/HOAtpss.html A classic activity in which students use rolls of toilet paper to measure of the scale of the solar system.
www.noao.edu/education/peppercorn/pcmain.html This classic "Earth as a peppercorn" model invites students to make a scale model of the planets' sizes and orbital distances using common household materials.
spacelink.nasa.gov/Instructional.Materials/NASA.Educational.Products/Solar.System.Puzzle.Kit/Solar.System.Puzzle.Kit.pdf The Solar System Puzzle Kit allows students to create an eight-cube paper puzzle of the solar system, reinforcing their knowledge of the planets. This guide is available free for download in PDF format.
hea-www.harvard.edu/ECT/the_book/Chap5/Chapter5.html Provides background information about the solar system, multiple scale modeling exercises, information and activities about ellipses and planetary orbits, lessons about radar mapping, why the sky is blue, Saturn's rings and Jupiter's atmosphere, planetesimals, and more.
netra.exploratorium.edu/ronh/solar_system/index.html This web page allows you to enter a size for the Sun, then it calculate the scaled diameters for all the planets and their orbits.
starchild.gsfc.nasa.gov/docs/StarChild/solar_system_level1/activity/solar_system_shuffle.html Match planet, moon, and solar system facts to the objects they describe, then have the computer check your answers.
amazing-space.stsci.edu/trading/directions.html This is a web-based interactive game in which students answer factual questions about the solar system and collect "solar system trading cards".
Web page by Challe Hudson. Copyright 2001 Morehead Planetarium.