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Orbit Demonstration

Orbit Demonstration

Ages 7-1220-30 minutesEasy Difficulty

About This Activity

Create a hands-on model to visualize how planets orbit the sun due to gravity, and learn about the basic principles of planetary motion in our solar system.

Materials Needed

  • Tennis ball (representing the sun)
  • Various smaller balls (representing planets)
  • Flashlight
  • Large flat sheet or thin blanket
  • Marbles of different sizes
  • Optional: String or chalk to mark orbital paths

Safety Notes

  • Be careful when using small marbles with younger children as they pose a choking hazard
  • Clear a large enough space to spread out the sheet completely
  • Keep the flashlight away from water or wet surfaces

Instructions

  1. Spread the large sheet on a flat surface or floor.
  2. Place the tennis ball (sun) in the center of the sheet.
  3. Press down slightly so the tennis ball creates a depression in the sheet.
  4. Place the smaller balls (planets) on the sheet at various distances from the tennis ball.
  5. Gently roll the smaller balls so they travel around the tennis ball in circular or elliptical paths.
  6. Use the flashlight to illuminate the setup from above to better see the orbits and shadows.
  7. Experiment with different speeds and distances to see how the orbits change.

How It Works

The depression created by the tennis ball represents the gravitational field of the sun. The sheet mimics space-time, which gets curved by massive objects. When you roll the smaller balls, they follow curved paths around the 'sun' similar to how planets orbit in our solar system due to gravity.

Tips for Success

  • Try using marbles of different sizes to represent different planets
  • Roll the marbles at different speeds to see how velocity affects orbit shapes
  • Mark the sheet with chalk or string to trace the orbital paths
  • Discuss why some planets orbit closer to the sun than others
  • For older children, introduce concepts like escape velocity and gravitational pull