Bonsall Elementary Model Solar System

In honor of Carl Sagan and in honor of the Sagan Planet Walk... and as a direct result of my son Charles' 6th grade Science Fair project, we have built a scale model of the Solar System that I think you will be interested in learning about.

On Friday, February 4th, 2000, in Bonsall, California... what I believe to be one of the largest and most accurate scale representations of the Solar System - viewable in one large unobstructed setting - was erected by myself, my son and some neighbors, in the school yard of Bonsall Elementary School.

The 440 foot model consist of yellow florescent construction cord radiating out from a Sun's position to the various planet positions. The angular positions depicted were for January 1st, 2000, at 0:00:00 UT. On the 'nail-head' of each position was placed a small printed laminated card (magnetized) illustrating the true diameters of the scaled Sun and the various planets. This model was three months in the making.

In our model, the Sun is 25 mm in diameter, about the size of a Quarter. The Earth, which is about one third the size of a period in this e-mail (0.23 mm), is 2.69 meters from the Sun's position. At the Earth's position we also depicted the Moon's location (which requires a magnifying glass to see it) plus, where the Earth would be one day later. Saturn (2.17 mm in dia.) is positioned 25.66 meters away and lonely Pluto (0.04 mm in dia.) and Charon sit out at 106.26 meters (approximately 348 ft).

Next to each of the planet's positions was a large laminated color picture of the Solar object with a listing of interesting facts printed on the back.

Our plan - for future presentations - is to have a teacher or older student stand near each of the various planet groupings. They would then describe some of the more interesting facts as groups of students came by 'on a solar tour'. Facts such as, how far a given planet is from the Sun, how long it takes sunlight to reach it, how much one would weigh on that planet (solid planets only), how long it will take for that planet to be back in the same position again... and, more scientific and historic data for the older groups, etc.

As we concluded our first tour on Friday the 4th, at Pluto's position, I asked the students which one would like to experience what it feels like to travel at the speed of light - "in the scale of our model". Of course, everybody raised their hand. I then had them line up facing our Sun's position 348 ft. away and told them that when I said "Go", they were to "rush" forward at the speed of "1 ft./min."... and that at THAT speed - the scaled speed of light - it would take them 5 1/2 hours to reach the Sun. They all laughed.


1) We selected a scale based upon the diameter of the Sun at 25 mm because it is about the size of a Quarter. As our group started out on tour I handed each member a Quarter. As we progressed farther and farther out from the Sun's position, I ask them to look at the Quarter in their hand and to reflect on the vast distances involved. At Pluto's position, I ask them to tell me what is keeping Pluto from wandering off on its merry own way. Of course, "gravity" was their answer. Then I pointed out, gravity yes, but specifically the lack of gravitational competition. I then pointed off in the distance while holding up my Quarter and named the next nearest star and its distance, in scaled miles, in relation to our model. Their mouth dropped. (At this point I collected my Quarters back!)

Our scale was also selected because it was the largest representation we could produce and still find a large flat grassy area big enough to display it "in an unobstructed fashion". It was also the smallest representation we could make and still represent the planet Pluto (which does require a magnifying glass to see). And... as an added benefit, it also allowed us to represent the speed of light at almost exactly 1 ft./min.

2) We developed our model using Adobe Illustrator 8.0, rendering the planet's diameters (and Earth/Moon positions) to 1/2400 parts per inch and HP's brand new 970Cse inkjet printer that can output at a maximum resolution of 2400 dpi on hard surface paper.

3) We used the "wondrous" Starry Night Pro planetarium program to compute the planet's angular positions to any point in time.

4) And, of equal importance and inspiration, we used Bill Arnett's fact filled web site entitled "The Nine Planets" to access the many facts and data points necessary to produce an accurate and interesting model.

Anyway, I believe, as members of the Sciencenter and the Sagan Planet Walk, you would be interested in this happening in our community. (Bonsall is a small farming and ranching community located 50 miles northeast of San Diego and 35 miles west of the Palomar Observatory.)

Ronald C. Shattuck
33 Via Alta Vista
Bonsall, CA 92003
(760) 726-4355

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