In this 45-minute activity, children ages 8 to 13 build edible models of Jupiter and Earth to compare their sizes and illustrate their internal layers. They discuss how the Juno mission will infer details about Jupiter's interior by measuring its gravity field and magnetic field.
What's the Point?
- The planets are made of solids, liquids, and gases.
- The solid Earth is layered with a solid surface crust; hot, convecting mantle; and dense, metallic core. Its gaseous atmosphere is thin compared to these layers.
- Movement of the fluid in Jupiter's liquid metallic hydrogen layer and Earth's molten outer core generate magnetic fields.
- Beneath Jupiter's thick atmosphere, there is probably no solid surface. It may have a dense core of rock surrounded by fluid metallic hydrogen, and above that, a layer of liquid hydrogen.
- The interior of a planet cannot be studied directly; scientists have inferred the composition from their observations.
- The Juno mission will collect indirect evidence about Jupiter's inner layers.
For each group of 20 to 30 children:
- Optional: butcher paper, newspapers, or disposable table cloths for the activity area
- Additional plates for eating the treats, if desired
For each team of 2 to 4 children (or for each individual child if you prefer that they make their own planets):
- 1 (8” diameter) paper plate
- 1 pitted cherry, cut in half
- 1 (2 1/4 ounce) strawberry Go-GURT® package or other yogurt
- 1 (5.5" to 6" diameter) strawberry-flavored gelatin jiggler (directions below)
- Strawberry syrup (several teaspoons)
- Chocolate syrup (pea-sized amount)
- 6 cinnamon candies (e.g. Red Hots)
- 1/4 cup whipped cream
- 1 ruler
- 1 plastic knife
- Several wet wipes or damp paper towels
- A Peek into Jupiter's Interior, preferably printed in color
For each child:
For the facilitator:
- Background information:
- Shopping list
- To prepare about 12 gelatin jigglers (if used in place of yogurt):
- 2 (11" x 17") cookie sheets
- 4 large packs of strawberry-flavored gelatin (or 8 small packs)
- 5 cups boiling water
- 1 large mixing bowl
- 1 knife for cutting jigglers
- Provide tables (covered, if desired) where the children can work and eat in teams.
- Prepare the gelatin jigglers beforehand: Pour boiling water into bowl and add the gelatin. Stir until completely dissolved. Pour the mixture into the pans to a thickness of about a quarter inch. Cool in the refrigerator for about three hours. Cut the jigglers into sixths — enough for one square for each of twelve teams.
1. Introduce the activity by dividing the children into teams of three to four and explaining that each team will create edible models of Jupiter and compare them to edible models of Earth. Invite them to share what they know about Jupiter:
- How do Earth and Jupiter compare in size? Which is bigger?
- Does Earth have layers inside? Can they name some of those layers?
- What is the inside of Earth like? Children may say there is a molten layer under the surface; this is an important misconception that will be examined in the activity.
- Imagine you could cut Jupiter in half with a knife and look at it insides. Does Jupiter have layers inside? What might they be like?
- Do you think Earth and Jupiter look similar on the inside?
2. Before you begin, explain to the children that this is a fun and tasty — but messy — activity! Have them wash their hands before they start and remind them to not lick their fingers while they are working on their models. For now, they will just make the model — they will be invited to eat them at the end of the activity!
3. Create a model of Jupiter! Provide the materials to the teams and invite them to follow the recipe in their journals, using A Peek into Jupiter's Interior for guidance. Ask them to slice their cherries in half and reserve one half for their Earth models. Have them note that the model will represent a slice of Jupiter through its middle.
Jupiter's rocky core: a pitted cherry half, stuffed with five Red Hots
Jupiter's liquid metallic hydrogen inner layer: strawberry-flavored yogurt or a gelatin jiggler, cut in a circular shape
Jupiter's molecular hydrogen layer: strawberry syrup
Jupiter's gaseous atmosphere: whipped cream
4. Create a model of Earth! Provide the materials to the teams and invite them to follow the recipe in their journals, using A Peek into Jupiter's Interior for guidance. Have them note that the model will represent the Earth, sliced in half to reveal its interior.
Earth's inner rock and metal core: a cinnamon candy
Earth's molten outer core: chocolate syrup
Earth's mantle: cherry flesh
Earth's crust: cherry skin
Earth's gaseous atmosphere: whipped cream
5. Invite the teams to examine the cross sections of their planets.
- How do their sizes compare? Jupiter is much larger! The entire Earth is about the same size as Jupiter's core.
- What do the different layers represent? Refer to steps 3 and 4.
- In what ways are they similar? They both have layers and a central solid core. Their cores are made of similar materials — rock and metals.
- How do these models represent the planets? Their overall sizes and the thicknesses of their layers are approximately to scale. Each layer is made of different materials.
- How do they not represent the planets? They are smaller and made of different materials than real planets. They represent just a slice through the planet rather than the entire sphere.
Facilitator's Note: With older children, continue with a deeper discussion comparing the structure and composition of Jupiter and Earth, as outlined in step 6.
6. With children ages 10 to 13, discuss how scientists study the unique interiors of Jupiter and Earth.
- In what ways are the interiors of Earth and Jupiter different? They are made of some different kinds of materials. Earth's core includes a layer of chocolate syrup that represents the liquid molten outer core. Jupiter has a large layer of liquid metallic hydrogen that is unlike anything found in (or on) Earth. Earth has a solid surface called the crust. Jupiter has another form of hydrogen forming a liquid layer. Jupiter's atmosphere — the part we can see from space — is not deep compared to the other layers, but it is very thick compared to Earth's.
- What properties can scientists observe to learn about planets? The children may have many ideas. Encourage those that relate to previous activities, including size, distance from the Sun, and appearance through a telescope.
Share that Earth's outer core, a molten layer of material — mostly iron — is very important. Convection (flow) of material in Earth's outer core creates Earth's magnetic field. As the children will explore in Neato-Magneto Planets, this magnetic field can be detected with compasses.
Facilitator's Note: Earth's magnetic field protects us from dangerous particles from the Sun called solar wind. Without a magnetic field, these particles would wear away our atmosphere and dangerous radiation from the Sun would reach Earth's surface.
While Earth's magnetic field protects us on the surface, it poses a danger to spacecraft that travel beyond Earth. The magnetic field traps radiation in the region of space surrounding Earth. Likewise, the area around Jupiter is filled with high levels of radiation. Much of the sensitive electronic equipment onboard the Juno spacecraft is housed behind titanium shielding to protect it. The spacecraft’s highly elliptical orbits will take it close to Jupiter's upper atmosphere, then direct the spacecraft to a safer distance and minimize the time spent in high–radiation areas. Even with this protection and careful planning, the spacecraft will slowly deteriorate as it orbits Jupiter. Over the course of 15 months, Juno will experience radiation that is equivalent to more than 100 million dental x–rays. Its electronics will eventually fail, but it is hoped that they will have collected data from a region of space where no humans can safely explore.
Invite the children to give their Jupiter models a gentle shake and observe the "jiggle" of its largest layer. That special layer of fluid within Jupiter — liquid metallic hydrogen — also creates a magnetic field through convection. Jupiter's magnetic field is very large and very strong, and Juno will map it. Understanding Jupiter’s magnetic field helps scientists understand the liquid metallic hydrogen layer that generates it.
- How can liquids exist inside a planet? They are HOT inside!
Add that the pressure of a planet's mass also crushes its internal layers, and some types of materials even become solid under those temperatures and pressure. The interiors of the Earth and Jupiter are not completely molten. The combination of composition, temperature, and pressure determine whether a layer is liquid or solid.
Facilitator's Note: The children may have many misconceptions about Earth's interior. They may believe the crust floats on a molten layer, but as modeled in this activity, only the outer core is liquid. Pieces of Earth's crust do move on top (giving rise to earthquakes), but they are riding a layer of ductile solid rock.
Ask the children to record the secrets they unlocked today in their journals with drawings and notes about their Jupiter and Earth models. Break out the spoons and enjoy the treats!
If possible, build on the children's knowledge by offering them a future Jupiter's Family Secrets activity. Invite the children to attend the next program, Weather Stations, to discover how Jupiter's "whipped cream" atmosphere holds turbulent weather and mysterious clouds.