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Investigating Science 11–12 · Year 11

A scale model of the solar system on the school oval

Module 3: Scientific Models

Practical, model not builtLow risk

This site has no interactive model of its own. Where a step or a material names a Concept Studio model, simulation or tool, it has not been built; an external simulation a step names (for example PhET) is not part of this site.

The idea

Built to one scale for both sizes and distances, the solar system is specks separated by enormous gaps, something no page diagram can show.

What you need

  • a trundle wheel or 100 m tape, marker cones or cards
  • a ball of about 93 mm diameter for the Sun; beads, seeds or pinheads for the planets, measured with a ruler or calipers
  • NASA planetary fact sheet values for diameters and distances

How to do it

  1. Choose the scale 1 astronomical unit (149.6 million km) = 10 m and calculate each planet’s model diameter and distance.
  2. Select objects of the right size for each planet.
  3. Pace out Mercury, Venus, Earth, Mars, Jupiter and Saturn from the Sun on the oval and place the cards.
  4. Mark Uranus and Neptune on a map of the school surroundings.
  5. Compare the model with a textbook diagram and list what each representation shows and hides.

What you should see

At 1 AU = 10 m the Sun (radius 695 700 km) is 93.0 mm across; Mercury sits 3.9 m out, Venus 7.2 m, Earth (0.85 mm) 10.0 m, Mars 15.2 m, Jupiter (9.6 mm) 52.0 m, Saturn 95.7 m, Uranus 191.6 m and Neptune (3.3 mm) 301.8 m, beyond most ovals. The Moon is a 0.23 mm grain 2.6 cm from Earth. The learner concludes that a diagram can show sizes or distances to scale but not both.

What changes

This activity lists no variables to change, measure and keep the same.

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

  • The planets are close together, as diagrams show them.
  • The planets line up in a row.
  • The Sun is about the size of the largest planets.

Safety card

Low riskLearners carry it out

Hazards

  • sun exposure
  • tripping on cones

Controls

  • hats and sunscreen
  • stay within the school grounds

Note

No hazardous chemicals or heat sources: record the activity in the school's RiskAssess risk assessment, following the NSW Department of Education Science safety and compliance page; the Chemical Safety in Schools package is not triggered.

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

Sources

The pages the author read to write this activity.

  1. www.nsw.gov.au/education-and-training/nesa/curriculum/science/investigating-science-stage-6-2017
  2. nssdc.gsfc.nasa.gov/planetary/factsheet
  3. nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html
  4. www.jpl.nasa.gov/edu/resources/project/make-a-scale-solar-system
  5. blog.doublehelix.csiro.au/make-a-solar-system-to-scale
  6. instructional-resources.physics.uiowa.edu/8a1015-scale-model-demos-solar-system

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