Lunar and Planetary Institute

Solar System

Activity: Hopping Across the Solar System

Children learn about the relative distances of objects in our solar system in this outdoor activity.

Before you start
Set up a Solar System Hopping Course in an outside area or in a long hallway. Mark each planet’s position with a stake or flag.

When the children begin “hopping across the solar system” you may want to have an adult present at each planet as the distances may be quite large, depending on the chosen set-up. Additional adults also can guide the children with questions and information and keep them moving to other planets. 

Following is one scale option for the course, with the distance reduced by a factor of 10 billion. This scale is appropriate for our solar system if the Sun were the size of a softball. There are many alternatives to presenting the activity, including halving or quartering the distances or leaving off the outermost planets.

            Sun (softball; 14 cm)                        0 meters (0 feet)
            Mercury (dot; 0.05 cm)                    5.8 m (19 feet)
            Venus (sand grain; 0.12 cm)             10.8 m (35 feet)
            Earth (sand grain; 0.13 cm)              15.0 m (49 feet)
            Mars (dot; 0.07 cm)                         22.8 m (75 feet)
            Jupiter (marble; 1.43 cm)                 77.8 m (256 feet)
            Saturn (marble; 1.2 cm)                   142.4 m (466 feet)
            Uranus (peppercorn; 0.51 cm)          286.7 m (941 feet)
            Neptune (peppercorn; 0.49 cm)        448.9 m (1473 feet)
            Pluto (dot; 0.02 cm)                         591.0 m (1939 feet)

The Activity

Invite the children to share what they know about the planets. You may want to use “The Solar System I’m Rhyme” song to refresh what they recall about our solar system.

  • What is the order of the planets?
  • How far away are they?

Divide the children into teams and give each team a planet name (or have them draw planets from a box). One team should be the Sun.
Give each team a paper plate and ask them to draw their planet (or Sun) in color, on the paper plate; they can use the color images for ideas. Provide each team with a small poster board and ask them to attach their planet plate to the board and label their planet’s name on the poster in big, bold letters.

Have the children line up in the order of the planets. If they are going to make an accurate model of the solar system, what things might they consider?

  • Are all the planets the same size? (No)
  • Are the planets the size of their planet plates? (No! the planets are much bigger!)
  • What about distance from the Sun? Are the planets all the same distance from the Sun? (No)

We use models to help us represent objects and systems so that we can study and understand them more easily.  Invite the children to make a scale model of the solar system. By “a scale model” in this case, we mean a model that has smaller parts but parts that are relatively the same size and distance to each other as the real planets and Sun are.

  • If the Sun were the size of a softball, how big would Earth be? (About the size of a grain of sand — 1/100 the size of the Sun)
  • How about Jupiter? (About the size of a large marble — 1/10 of the size of the Sun)

Mercury and Pluto would be very tiny specs in this model!

Invite the children to draw a circle or dot or spec on their poster that represents the size of the planet if the Sun were the size of a softball.

Provide each child with the Hopping Across the Solar System board and a crayon. Invite them to go outside to your Solar System Hopping Course. With the help of adults, have the planet groups attach their posters at the appropriate stake or flag.

Invite the children to explore the distances from the different planets to the Sun, and the distances between planets. Each child should hop from one planet to the next, counting the number of hops needed to reach the planet. Have them write that number on their Hopping Across the Solar System board.

As they reach different planets, have the children look back at the Sun. How big is it?

Once the children have finished, regroup!  Have them compare the number of hops they made between the different planets. 

  • Did they miss running into an asteroid between Mars and Jupiter?
  • What did they notice about the distances from the Sun to the inner planets versus the distance to the outer planets? (The inner terrestrial planets — Earth, Mercury, Mars, and Venus — are much closer together. The planets get farther and farther apart.)
  • How long would it take a spacecraft to get to these other planets? (Part of this answer depends on the type of spacecraft and if it is doing other things like circling other planets. In general, it would take a spacecraft about 5 and a half months to get to Mercury if it was going in a straight shot; MESSENGER spacecraft, launched in 2004, will get to Mercury in 2011; MESSENGER is doing several loops around other planets before it arrives to orbit Mercury. And New Horizons, launched in 2006, is expected to reach Pluto at the “other end” of our solar system in 2015!)
  • What do they think happens to the temperatures as you get farther from the Sun? (In general, the greater the distance the colder the temperature! Temperatures are a scalding 380°C (715°F) on Mercury, -70°C (-94°F) on Mars, -143°C (-225°F) at Jupiter, and a frigid -235°C (-390°F) at Neptune and Pluto.)
  • How far away — at the scale of the game — is Alpha Centauri, our nearest star (besides our Sun)? (At this scale, Alpha Centauri would be about 11 centimeters across and 3,200 kilometers (2,000 miles) away, roughly the distance from New Orleans to San Francisco!)


More Activities


Children ages 5–12

How Long?
60 minutes or longer

What’s Needed?

  • 10 stakes or flags that can be placed outside to mark the positions of planets; the stakes need to be seen by the children from great distances.

For each child:

For each group of children:

  • White paper plate
  • Crayons or colored markers
  • Tape or glue
  • 11x17 sheet of poster board or cardboard
  • Images of the planets, such as those found at NASA's Planetary Photojournal Web site.

Connections to the National Science Standard(s)


Standards D (grades 5–8): Understand and communicate that 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. These objects orbit the Sun. Most objects in our solar system are in regular and predictable motion.