Lunar and Planetary Institute

Children reinforce their understanding of the cause of seasons on Earth and extend this knowledge into our solar system, as they model seasonal changes on planets.

Before you start: The children should understand why Earth has seasons. Activities exploring seasons can be found here.

Invite the children to discuss seasons (information can be found in “About Seasons”). What did they learn in the SkyTellers science story? Note their responses — correct and incorrect — to revisit at the close of the activity.

• What causes seasons on Earth? (Earth's axis is tilted relative to its plane of orbit and points in a fixed direction as it orbits our Sun, thus different parts of our globe are “pointed toward” our Sun, experiencing summer at different times of the year)
• Does distance from the Sun affect Earth's seasons? (Not really, as there is such small variation in Earth's orbital distance)
• Do other planets have seasons? (Yes)
• What would cause seasons on other planets?
• Could distance be a factor in the seasons on other planets? (Yes, if a planet's path around the Sun takes it significantly closer to the Sun in one part of its orbit than another part, like Mercury)

Divide children into groups and provide each group with the Tilt and Time Table.

• What is axial tilt? (How much a planets' pole of rotation is from being perpendicular to the plane of its orbit around the Sun)
• What do they observe about the tilt of different planets?
• What might this mean about seasons on different planets?
• Which planet will experience the most extreme seasons?
• Which will not experience seasons because of tilt? Why?

Assign each group a planet and provide them with a Styrofoam ball. Invite them to decorate their planet, using toothpicks to mark the planet axes — one for each pole.

• All the planets are the same size in the model — is this true in our real solar system? (No)

Once the planets are decorated and have north and south axes, ask one child to represent the Sun. Ask another from each group to hold the group's planet and stand in the order of the planets, from the closest to the Sun to the farthest. The children should be a few feet apart. The other children can help determine the correct order of the planets.

Have “Earth” walk (orbit) around the Sun, maintaining its axial tilt (~23.5 degrees) and keeping the axis pointed to the same place in the room.

• When does winter occur for the northern hemisphere? Spring?  Fall? Summer?
• What is changing as Earth moves around the Sun?
• Repeat for Jupiter or Uranus.
• What are their seasons like? (Jupiter has very little, or no, axial tilt, so it does not have seasonal differences; the distribution of incoming sunlight does not change throughout the year)
• What about Uranus? (Uranus has an extreme tilt of 82 degrees. This means that when one pole is pointed toward the Sun (summer), the opposite hemisphere is in constant darkness (winter). Given Uranus' 84-year orbit, each season is about 20 years long!)
Continue with the other planets. How long would each season be? Have the children imagine what it would be like to live on those planets as the seasons changed. How long does it take for the planet to orbit the Sun? How long is each season?

Tilt and Time Table

 Name Axial Tilt Time for One Orbit Around the Sun (one year) (in units of Earth years and days) Planetary Size (scaled to millimeters) Distance from the Sun (scaled to meters) Mercury 0° 88days 9 mm 57.91 Venus 177° 225 days 21 mm 108.20 Earth 23° 365 days 23 mm 149.60 Mars 25° 687 days 12 mm 227.94 Jupiter 3° 12 years 250 mm 778.33 Saturn 27° 29 years 220 mm 1429.40 Uranus 98° 84 years 90 mm 2870.99 Neptune 30° 164 years 87 mm 4504.30 Pluto 120° 248 years 4 mm 5913.52

More Activities

Last updated
January 4, 2007

Who?
Ages 10–16

How Long?
45–60 minutes

What's Needed?
For each group of children:

• 1 “Tilt and Time Table”
• 1 Styrofoam ball at least four inches in diameter
• Colored markers
• General craft materials (glue, glitter, pipe cleaners, etc.)
• Two toothpicks

Connections to the National Science Standard(s)

Standards A&D (grades 5–8): Identify questions about seasonal changes using their own observations. Use data to answer questions about how objects in the solar system have regular and predictable motion that explains such phenomena as seasons. Critique and communicate explanations.

Standards A&G (grades 9–12): Identify questions about seasonal changes using their own observations. Using logic and mathematical data, formulate an explanation about and conceptual understanding of how axial tilt affects seasonal variations. Critique and communicate explanations.