The Badge Archive

Activity Description: Scouts measure and draw circles to show how the planets compare in size.

• Fulfills Step 1 of GSUSA Brownie Space Science Adventurer and Junior Space Science Investigator badge requirements.

Info Needed: Planets in our solar system are very different in size. Explore the Solar System in a hands-on, memorable way.

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Items Needed:

• Chart showing scaled planet diameters
• Rulers or measuring tapes
• Large sheets of paper or sidewalk chalk
• Pencils or markers
• (Optional) Pre-cut string lengths for each planet
• (Optional) Labels or printed planet names
• (Optional) Tape or glue if using cut paper circles

Instructions (Estimated Total Time: 25–35 min):

1. Review the planet size chart (3–5 min)
   • Scouts look at the chart to see how wide each planet should be.
   • Explain that the circles will be scaled to fit the space available.
2. Measure and mark each circle (8–10 min)
   • Scouts use rulers or string to measure the correct diameter for each planet.
   • Mark the center and edge points before drawing.
3. Draw the circles (8–10 min)
   • Scouts carefully draw each circle using their measurements.
   • Use sidewalk chalk outdoors or markers on paper indoors.
4. Label and compare (5–7 min)
   • Scouts label each planet and look at how the sizes compare.
   • Ask which planet surprised them the most or looked different than expected.
5. (Optional) Display or save the drawings (2–3 min)
   • Tape paper circles to a wall or take a photo of chalk drawings before cleanup.

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Planet Circle Sizes for Activity

Planet	Actual Diameter (km)	Relative to Jupiter	Scaled Circle Diameter (inches)
Jupiter	142,984	1.00	7.5
Saturn	120,536	0.84	6.3
Uranus	51,118	0.36	2.7
Neptune	49,528	0.35	2.6
Earth	12,756	0.089	0.67
Venus	12,104	0.085	0.64
Mars	6,792	0.047	0.35
Mercury	4,879	0.034	0.26