June 16, 2021: A summer project is to build a sidewalk solar system model. The scale uses the sun’s size as the size of a basketball. Earth’s distance is 88 feet.
by Jeffrey L. Hunt
Build a sidewalk solar system model. It’s a great summer project to show children the relative sizes and distances of the sun and planets.
The equipment needed is a tape measure (the longer, the better), sidewalk chalk for temporary markers or spray paint for a longer-term model.
With any model, making all the scales work is the challenge. This is evident with the relative sizes and distances of the planets. Can we make the planets large enough, but keep their distance from the sun reasonable? Well, not really. A long neighborhood sidewalk is needed.
We start with the sun’s actual diameter, 840,000 miles. Let’s reduce it to the diameter of a basketball, about 9.55 inches. At this scale the planets’ sizes are tiny, especially the inner planets until Jupiter is marked. Then place the planets at their distances from the sun.
| Object | Scale size (inches) | Scale Distance (feet) |
| Mercury | 1/32 | 34.3 |
| Venus | 1/10 | 63.4 |
| Earth | 1/10 | 88 |
| Mars | 1/20 | 133 |
| Jupiter | 15/16 | 457 |
| Saturn | 13/16 | 838 |
| Uranus | 5/16 | 1690 |
| Neptune | 5/16 | 2646 |
If you’re building a classic solar system, including Pluto, its distance from the sun in 2021 is 3018.4 feet from the sun. The planet is small, only 1/200 inch, just a tiny dot.
Have fun with this model.
Articles and Summaries
- Venus as an Evening Star
- Venus Evening Star (Summary)
- Mars during 2021 (Summary)
- Planets during June 2021
LATEST ARTICLES
- 2023, December 26: Cold Moon, Venus, Jupiter, Saturn
December 26, 2023: The Cold Moon is visible during the nighttime hours. Venus shines before sunrise while Jupiter and Saturn are visible after sundown. - 2023, December 25: Telescope First Light, Bright Planets
December 25, 2023: For sky watchers with new telescopes, here’s what to look at before dawn or after sunset. - 2023, December 24: Morning Moon, Pleiades, Antares Heliacal Rising
December 24, 2023: The moon appears near the Pleiades star cluster during the earlier morning hours. Antares is at its first morning appearance, known as the heliacal rising. - 2023, December 23: Check out Planet Uranus, Pleiades near Moon
December 23, 2023: Look for the planet Uranus and the Pleiades star cluster through a binocular during nighttime hours. - 2023, December 22: Mercury at Inferior Conjunction, Bright Jupiter, Gibbous Moon
December 22, 2023: Mercury is between Earth and Sun, known as inferior conjunction. Jupiter and the gibbous moon are celestial companions during nighttime hours.
