Solar system to scale on the oval

The idea

At one scale the planets are specks metres to hundreds of metres apart, which no textbook diagram can show without breaking the scale.

What you need

• the NASA Planetary Fact Sheet distances and diameters (Mercury 57.9, Venus 108.2, Earth 149.6, Mars 228.0, Jupiter 778.5, Saturn 1432.0, Uranus 2867.0, Neptune 4515.0 million km)
• 1 trundle wheel or 50 m tape; 8 marker flags
• a 14 cm ball (the Sun at 1 to 10 billion), 2 pins with 1.3 mm heads (Earth and Venus), 1 grain of sand for Mercury and Mars, a 14 mm marble or bead for Jupiter and a 12 mm bead for Saturn, 2 peppercorns for Uranus and Neptune (5 mm)
• 1 roll of adding-machine tape for the JPL Solar System Scroll folding version indoors

How to do it

1. Choose the scale 1 to 10,000,000,000 (1 cm = 100,000 km). Compute each planet's distance in metres and diameter in millimetres before going outside.
2. Place the Sun ball at one end of the oval and pace out each planet's distance with the trundle wheel, planting a flag with its object.
3. Stand at Neptune and look back: record whether the Sun ball is still visible and whether any planet is.
4. Indoors, fold the adding-machine tape as in the JPL Solar System Scroll (halves and quarters) and check the folded positions against the computed distances.
5. Compute where Pluto would sit at this scale from its distance in the same fact sheet (5,906.4 million km) and whether it would fit on the school grounds.

What you should see

At 1 to 10 billion the Sun is a 13.9 cm ball, Earth a 1.28 mm pin head 14.96 m away, Mars a 0.68 mm grain 22.8 m out, Jupiter a 14.3 mm pea at 77.9 m, Saturn 12.1 mm at 143.2 m, Uranus 5.1 mm at 286.7 m and Neptune 5.0 mm at 451.5 m; the Moon sits 38 mm from the Earth pin. The whole model needs a straight line of 452 m: the inner four planets fit within 23 m of the Sun, while Uranus at 287 m and Neptune at 452 m run past the edge of most school ovals, which is itself the lesson; the dwarf planet Pluto would sit 590.6 m out. The learner knows the model worked when each planet from Venus outward sits 1.38 to 2.01 times as far from the Sun as the one before, apart from the 3.4 times jump from Mars to Jupiter, and the inner four planets crowd within 23 m of the Sun.

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.

• Planets are evenly spaced; each planet from Venus outward is 1.38 to 2.01 times as far from the Sun as the one before, with a 3.4 times jump from Mars to Jupiter.
• Diagrams showing planets side by side at one scale are to scale; at any scale that shows planet sizes, the distances do not fit on a page.

Safety card

Curriculum references

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

• Science 7-10 Syllabus (2023), NSW Education Standards Authority (implemented from 2026; codes read at curriculum.nsw.edu.au on 22 and 23 September 2026)SC4-OTU-01SC4-WS-04SC4-WS-05
• Australian Curriculum v9AC9S7I04

Sources

The pages the author read to write this activity.

1. curriculum.nsw.edu.au/learning-areas/science/science-7-10-2023/outcomes
2. vocabulary.curriculum.edu.au/MRAC/2024/04/LA/SCI/export/MRAC/2024/04/LA/SCI.jsonld
3. nssdc.gsfc.nasa.gov/planetary/factsheet
4. www.jpl.nasa.gov/edu/resources/lesson-plan/solar-system-scroll
5. nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html
6. hyperphysics.gsu.edu/hbase/kepler.html