On July 19, 2013, Cassini slipped into Saturn's shadow and turned to image the planet, seven of its moons, its inner rings and Earth.


In this activity, split into three 30-40 minute sessions, students will:

  • Experience the vastness of the solar system and the size differences among the Sun, our home planet Earth, and this unit’s theme — Saturn.
  • Walk a playground or other large area to create a scale model for size and distance in our solar system. A variation for an indoor model is included.
  • Participate in the creation of an orbital (“radial”) scale model of the solar system.
  • Compare their early thoughts about the solar system to their new experience and questions once they have participated in the scale and distance exercises.
  • Reflect on what it would be like to travel to Saturn.
  • Activity Goals: Start to understand scale — in size and distance — in comparing the Sun, Earth, and Saturn; begin to learn about Saturn and the Cassini-Huygens mission and spacecraft; practice the scientific thinking skills of predicting, comparing, and relating.

Note: This activity is part of the Jewel of the Solar System activity guide, which includes:

  1. What Do I See When I Picture Saturn?
  2. Where Are We in the Solar System? (current activity)
  3. Discovering Saturn: The Real "Lord of the Rings"
  4. Saturn's Fascinating Features
  5. My Spacecraft to Saturn
  6. All About Titan and Huygens Probe
  7. Drop Zone! Design and Test a Probe
  8. Celebrating Saturn and Cassini



Space Needed

  • Session 1 and 3: Classroom, cafeteria, or other space with tables, chairs, and extra floor space

  • Session 2: School campus (to fit at least 247 yard-long walking paces)

Sessions 1 and 2

  • Cut out the images for the Sun on a stick, Earth on a stick, and Saturn on a stick, and glue each to a separate piece of thin cardboard or a manila folder. Tape each object to a tongue depressor or craft stick so that students can easily hold them.
  • Solar system scale model

    Prepare the Chart of the Size Models for Walk on the Wild Size as shown here. Image credit: NASA/JPL-Caltech

  • Prepare the Chart of the Size Models for Walk on the Wild Size as shown (right). (Be sure to draw and label a 1-inch bar.) You will use this chart to show the students how the scale of the model compares to the actual distances in the solar system, and what distance in space one pace represents.

  • Brief yourself on the Instruction Sheet from "Take a Walk on the Wild Size," and, optionally, print it out for each student to take home.

  • Identify a large portion of a school campus. Because the distances in space are so big (247 yard-long paces to Saturn, 1019 paces to Pluto!), everyone will need to take a short hike to complete this model.

Session 3

  • Tape and/or glue butcher paper or 4 poster boards together to create a large square (about 2 meters on a side).

  • Mark the center of the square, for the Sun’s position in the model.

  • Pre-cut a piece of string to be 80 cm or longer.

  • Write the name of each planet on the right half of a separate piece of tape. (These will be used to wrap around the string.) Since the inner planets are so close together, you might need to put several inner planet names in order on a single wide piece of tape, and/or cut the tape into narrower strips.

  • Distribute each student’s Saturn Discovery Log back to him or her for journaling.

Equity/Leveling the Playing Field

  • In this activity, youth present their work to the group. This may be more comfortable for some than others.

  • Create an environment where they will feel comfortable presenting in front of the group telling them that they should think of themselves as “critical friends” who give positive constructive input.

  • Explain that critical friends will give positive feedback and helpful suggestions for improvement.

  • “Mirroring” is a good way to ensure this will happen, such as: “What I like about your work is...” “What you drew that is missing from my drawings is…”

  • This can be followed by a “critical friends” statement, such as “What I would change about your drawing is…”

  • Emphasize the idea of being supportive and helpful.

Leader Tips

  • Pace out the walking scale model in advance yourself to find the best location and to anticipate student questions. A very large space is required. It’s impressive when done, but not every site has this kind of space. This scale was chosen to correctly model the size of the Sun to the distances to the planets at the same time. (All numbers are rounded.) See “Taking Science to the Next Step” if you need to adapt the walk for a smaller/ indoor space.

  • Set any ground rules you need to before taking the group outside — this could include staying with the group at all times or agreeing on a signal that it’s time to stop.

  • Some cities make their own permanent solar system scale models, such as the Smithsonian Institution in Washington, DC. See the webpage here for a partial list.


The sizes and distances that we explore in space are far greater than those we are accustomed to on Earth. Students (and adults) may not easily grasp the enormity of space or the size difference between Earth, the Sun, and the other planets.

Our solar system contains our star (the Sun), eight planets, dwarf planets, moons, and a variety of other objects.

Distances in space are so vast that scientists use astronomical units (AU) for measurement. An AU is the distance from Earth to the Sun — 150 million kilometers or 93 million miles.


  • Astronomical unit (AU): The distance from Earth to the Sun (93 million miles, or 150 million kilometers).
  • Diameter: The length of a straight line through the center of an object — so, the diameter gives us the measurement of how far it is across a planet, moon, or the Sun.
  • Model: A graphical or 3-D example for imitation or comparison; a representation (sometimes in miniature) to show how something is configured or constructed.
  • Radial: Radiating from, or situated around, a common center (the Sun).
  • Solar system: The collection of planets and other bodies that revolve around the Sun.


Session 1 – Wondering About and Sizing Up What’s Out There (About 30 minutes)

  1. Lead the children in sharing their ideas about our solar system. Capture their thoughts on a white board or chart paper. (Do not worry about whether an idea is right or wrong for the moment.) Some suggested questions are:

    • What planets have you heard about in our solar system?

    • What other kinds of bodies or objects have you heard about out there in the solar system?

    • What have you heard about traveling in space?

    • What questions do you have about the solar system?

  2. Explain to the students that over the next few sessions, the group will learn about the planet Saturn and think about what it would be like to go that far into the solar system. Explain that they will model the size of the Sun, Earth, and Saturn, and how far they are apart, at the same time.

  3. Ask the students: How many stars do you think there are in the solar system? Reveal that there is only one – our Sun. Explain that our Sun is also the largest object in our solar system — it would take a little more than 109 Earths to span the Sun’s diameter. Remind students that the Sun is in the center of the solar system and the planets orbit (go around) the Sun.

  4. Show the students the Sun on a stick that is approximately 8 inches in diameter, and say: This is a model of the Sun. Then Ask: If this were our Sun, how big do you think Earth would be? How big do you think Saturn would be? Have them guess.

  5. Show the students the Earth on a stick and Saturn on a stick models, revealing the true scaled size for Earth and Saturn in this model.

  6. Display the Chart of the Size Models for Walk on the Wild Size you created and have the students take turns reading it out loud. Emphasize that each “giant” (yard-long) step represents 3.6 million miles (5.8 million kilometers - km) on the actual scale of the solar system! Then have them estimate some distances using this conversation guide:
  7. Now that we have established the size scale for the Sun, Earth, and Saturn, how much space do you think we need to build our scale model of distances between them?

    Let’s have one volunteer come to the front of the room and be the Sun. (Have the volunteer hold the Sun stick.)

    Let’s have another volunteer be the Earth and stand next to the Sun. “Earth” will keep taking giant steps away from the Sun in a straight line and you all count them. Call out “Stop” as soon as you think that “Earth” is far enough from the “Sun.” (The correct distance is 26 giant steps. If the students stop “Earth” earlier, respond “Not far enough” until they run out of room or get to the right distance.)

    The distance between Earth and the Sun is, on average, about 93 million miles (150 million km), or in our model, 26 giant steps.

    How far apart do you think you need to stand to model the distance from the Sun and Earth to Saturn? (Have a volunteer come up to stand where the students think Saturn would be.)

    We’ll learn the right distance for Saturn in our next session, and walk the distances to the other planets. For that, we’ll need to go outside!

  8. Collect the Sun, Earth, and Saturn stick models.

  9. (Optional) Leader Reading: Read aloud the last 2 paragraphs of page 3 from the mini-book “Introducing Saturn,” showing the illustrations.

Quick Facts Reference: Size Comparison

  • The Sun’s diameter is about 864,337 miles (1,390,718 km).

  • Earth’s diameter is about 7,918 miles (12,740 km).

  • Saturn’s diameter is about 74,913 miles (120,535 km).

  • It would take about 109 Earths to span the diameter of the Sun.

  • It would take about 12 Saturns to span the diameter of the Sun.

  • It would take about 9.5 Earths to span the diameter of Saturn at the equator.

Session 2 – Taking a Walk on the Wild Size (About 40 minutes)

  1. Repost the Chart of the Size Models for "Walk on the Wild Size" in the room.

  2. Prepare the students for their walking adventure through the solar system, using this conversation guide:
  3. Most of you have had some kind of experience with models. A model is a representation of something else, often something too big, too small, too far away, or too complicated to observe directly.

    Scientists and engineers often build models to test a challenge or visualize how something will work. The model could be as simple as drawing something on a white board so that everyone sees the same thing, and as complex as creating a computer program to test how their spacecraft will land on a planet. When scientists want to send a spacecraft to space, they often make a model of their destination to figure out how best to get there.

    For our model, as we make the trip to Saturn, the distances are so big that we’ll need to go outside.

    We’ll be pacing the distances from the Sun to the orbits of the planets, walking in a straight line. While this model is true for size and distance comparisons, it is not true for the locations of planets in their orbits around the Sun. A straight line-up of the planets essentially never happens. Since models are only representations, they don’t represent everything accurately.

  4. Point out the facts on the Chart of the Size Models for "Walk on the Wild Size" and again emphasize that for each “giant” (yard-long) step, you would travel 3.6 million miles on the actual scale of the solar system!

  5. Prepare the group to go outside, and make any recommendations for rules of conduct while there. Take and use the instruction sheet for "Take a Walk on the Wild Size."

  6. Have the students line up at your selected large and/or outdoor location. Using the instruction sheet, begin pacing together, and read off the distances as you go, beginning at the Sun.

  7. Once you have completed the walk, get their impressions:

    • What surprised you about the distance?

    • What do you notice about how the Sun looks from Saturn compared to how it looked from Earth? (e.g. The Sun is a smaller size. You cannot see as much detail on the Sun from Saturn’s distance.)

Session 3 – Creating a Radial Scale Model (About 40 minutes)

  1. Prepare the students to think about a different kind of model, using this conversation guide:
  2. Earlier we made a model to show the distance between planets and the Sun. Now we are going to make a radial model for the planets’ distance from the Sun. The radial model shows the planets in their orbit around their common center — the Sun. Scientists, too, often create different models of the solar system for different purposes.

    As we saw in the last session, because distances in space are so large, scientists have come up with different ways of measuring these distances. They use an astronomical unit (AU) for the distance from Earth to the Sun (about 93 million miles, or 150 million kilometers). Other measurements in space are then referred to as the number of AUs between two bodies (or the number of 93-million-mile segments).

  3. Spread out the sheet of butcher paper/poster board and mark the Sun at the center.

  4. For this model, every astronomical unit (AU) is about 2 centimeters (cm). Ask students to predict where they think Earth and Saturn will be, relative to the placement of the model Sun. They can also predict how many astronomical units they think this will be.

  5. Measure the different distances along the string and put the piece of tape marked with each of the planets’ names.
  6. PlanetScale Distance (in cm)Actual Average Distance (in Astronomical Units, or AU)
    Mercury0.8 cm
    0.4 AU
    Venus1.5 cm
    0.7 AU
    Earth2 cm1 AU
    Mars3 cm1.5 AU
    Jupiter10 cm5 AU
    Saturn19 cm9.5 AU
    Uranus38 cm19 AU
    Neptune60 cm30 AU
    Pluto (Dwarf Planet)79 cm39.5 AU
  7. On the large paper, attach the piece of string to the center of the Sun. Have the students mark the planets at the appropriate distance, as you rotate the string around the Sun as each planet is placed. Planets should be spread out in several directions — not lined up as they were in the earlier model.
  8. Solar system scale model

    Your final model should look something like this. Image credit: NASA-JPL/Caltech



Prompt a discussion about the activity with your students using this conversation guide. (Suggestions for starting/continuing the conversation are included):

  • What surprised you?
    It’s a lot farther between each planet and really far to Saturn.

  • What do you notice?
    The radial model shows that the planets don’t line up in a row.

  • What do you notice about how the Sun looks from Saturn compared to how it looks from Earth?
    The Sun is a smaller size. You cannot see as much detail on the Sun from Saturn’s distance.

  • Do you think it is colder on Saturn than Earth?
    The heat from the Sun is much less because it is much farther away.

  • What problems or challenges do you think a spacecraft has to overcome in order to travel from Earth to Saturn?
    The spacecraft needs enough energy to make all the instruments and cameras work during the several-year flight to Saturn.

  • What kinds of information about Saturn and Titan do you think a spacecraft could gather that we are unable to gather from Earth?
    Because it is close to Saturn, it can see clouds and landscapes better. The spacecraft can take better pictures to send back to Earth

  • What questions do you have?
    I wonder ...? What if ...?

Sharing the Findings

  • Ask students to work in teams and spend a few minutes writing down everything they just discovered or learned in their Saturn Discovery Logs. Ask them to also list all of their new questions.


After the activity, ask yourself the following questions:

  • Did the students show a curiosity to learn more about the solar system?
  • Did the students’ discoveries indicate an understanding of the immensity of our solar system? Of how far away Saturn is?
  • Did the students understand that the planets are not lined up in a row, but in orbit around the Sun?


Information for Families

  • Do the parents in your program have busy schedules — does working and taking care of the kids leave time to go to a museum? Is it difficult to get to museums? Use your Web browser and search for “science museum virtual tour” for locations that can be visited online or with a smart phone. Young people today are living during the most amazing era of exploration in human history. For the first time, we are able send back pictures and information from other worlds. Encourage parents to share the adventure with their children at the SpacePlace parent’s page.

Careers at NASA

  • What would a career exploring other worlds be like? How can you work at JPL as a student? Find out here. How can you work at JPL as an adult? Find out here.

  • Ask students to brainstorm a new “job at NASA.” What would it be? What would that person try to find out? Describe the mission that person would lead. Chart the students’ responses.

Role Model Resource

Ed Stone

Dr. Ed Stone is a professor of physics at the California Institute of Technology and the Chief Scientist for Jet Propulsion Laboratory’s Voyager mission, which has traveled to the outer planets making amazing discoveries, and continued the journey beyond to the boundaries of our solar system. Since the launch of the two Voyager spacecraft in 1977, Dr. Stone has coordinated 11 teams of scientists in their investigations of Jupiter, Saturn, Uranus, and Neptune, and became nationally known as the JPL public spokesman during the planetary flybys, explaining the Voyagers’ scientific discoveries to the public. He later served as the Director of JPL. He’s interested in how things work — science is, after all, about understanding how nature works. He found that learning about how things work is best done by actually trying to make and build things! He also feels that to be a successful scientist, as in most aspects of life, you need to develop skills for good listening and for talking with people. Watch a video about Ed and Suzanne Dodd, the Voyager project manager. | Learn more about the Voyager missions


To help you visualize representations of the solar system and Saturn’s place in it, check these out:

Taking Science to the Next Step

  • If you need a smaller space for the scale model (such as a gym or playground), divide everything by 10:

    • On “photo” setting, photocopy at 10 percent reduction the Sun, Earth, and Saturn image page. (Your copier may require you to do two reductions at 33 percent each instead.) Earth will be a pinpoint at this scale.

    • In the Chart of the Size Models for "Walk on the Wild Size," change the model Sun’s diameter to 85/100 of an inch (0.85), model Earth diameter to 8/1000 of an inch (0.008), and model Saturn diameter to 75/1000 of an inch (0.075). One inch in this model represents 1,000,000 miles (1:1,000,000).

    • Divide the number of steps needed by 10 (round to the nearest whole number) before pacing. Send home the directions for pacing the solar system, so students can do the activity again with family and friends. Convert the size model and pacing model to metric units, which are commonly used by engineers! (As you learn more about astronomy, read different books, and visit different websites, you may find information presented in miles, kilometers, or both.) Here is an easy way to convert from miles to kilometers, and kilometers to miles — 1 mile = 1.609 kilometers.

    • To convert from miles to kilometers (km), multiply by 1.609. For example, if the diameter of Saturn is 74,913 miles, multiply 74,913 miles by 1.609 km per mile = 120,535 km.

    • To convert from kilometers to miles, divide by 1.609. For example, if the diameter of Saturn is 120,535 km, to find out miles, divide 120,535 km / 1.609 km per mile = 74,913 miles.

  • Make other models of the solar system: see the “Solar System Model Builders’ Guide” on the Museum Alliance website.

  • If there’s enough space (for example, a football field), try pacing out the solar system but instead of lining up the planets, ask each student representing a planet to walk in a different direction and create a radial model. This way, students will understand that the planets are not “all lined up” in a straight line.


  • Ask the students to write a short science fiction story about going to Saturn. Tell them to include as many Saturn or space facts as possible. Include information like how far away Saturn is, or the name of its largest moon, Titan. Share the stories with the children. Discuss why it took Cassini seven years to get to Saturn.