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When Julián Gómez-Cambronero’s daughter Julia was in the fifth grade, she had a homework assignment to draw a picture of the solar system. Cambronero, a professor of biochemistry and molecular biology at Wright State University, challenged the little girl’s colorful yet not-to-scale picture. In reality, the planets are not equidistant.

If the sun were located in their kitchen, then Mercury would be in the living room, and Venus would be in the yard, Cambronero explained to his daughter. Earth would be across the street, Saturn would be all the way at her school, and Neptune and Pluto would be in the neighboring city.

Upon seeing Julia’s dawning comprehension, Cambronero was inspired to construct a scale model of the solar system. By actually walking the distances between the planets people – and children especially – could tangibly appreciate the enormous distances of the solar system, he reasoned.

The summer after this inspirational homework assignment, while Cambronero was on vacation visiting his parents, he contacted the mayor of his hometown, Manzanares, in central Spain. The town has about 20,000 people, and though Cambronero emigrated to the U.S. many years ago, he says he still knows pretty much everybody. Eventually, he wrote a proposal and won funding from the municipality to construct the educational and eye-catching combination of science and art.

Cambronero’s initial idea of simple traffic-sign-like markers through the city underwent an evolution, and three years later, in September 2010, the final Walk Through the Solar System opened in a public park in Manzanares. This quarter-mile brick walk through the city park is studded with 6-foot-tall steel monoliths holding beautiful Fiberglass planets on rotatable axes with informational yet entertaining placards.

Construction challenges

Julián Gómez-Cambronero invites you to visit the Walk Through the Solar System the next time you are in central Spain.

Fast facts

• Earth’s moon, included in the model, is the largest moon relative to the size of its primary. NASA landed people on the moon six times between 1969 and 1972.
• Jupiter, a gas giant, is the largest planet in the solar system and is roughly beach ball-sized in the model. The NASA space probe Voyager 1 first discovered Jupiter’s dusty rings in 1979.
• Cambronero included included in his model the dwarf planet Pluto, which was reclassified in 2006 along with Eris and other sufficiently massive celestial bodies in the Kuiper Belt. This summer, the NASA space probe New Horizons will visit Pluto to determine its geology, chemical composition and atmosphere.

The construction of the installation was not a simple walk in the park. Cambronero had to coordinate contractors and artisans from halfway around the world. Even in the design stage, he ran into some difficulties. Determining the scale of the orbital distances was easy given the limit of the size of the park, but he could not use the same scale for the diameters of the planets. “If you were to use the same scale,” he says, “the size of the Earth would be microns!”

Deciding on the scale for the planets’ diameters was difficult because both the sun and Pluto have to co-exist. “I knew that the sun is much bigger than the Earth – everybody knows that – but I didn’t realize how big it is, so absolutely huge,” Cambronero says. The first scale he considered was based upon making Earth the size of a basketball, but then the sun would have to be almost 25 stories tall!

Even rescaled based upon an Earth the size of an orange, the sun’s diameter of 27 feet was too big to manufacture as a Fiberglass sphere. So, instead, Cambronero decided to represent the sun with a 27-foot steel ring around a 7-foot Fiberglass sphere. On this final scale, dwarf planet Pluto is a mere half-inch in diameter, smaller than a grape.

New generations

Last year, 19 elementary school classes, seven middle and high school science classes, four library field trips, and three amateur astronomy groups from Manzanares visited the model. Roughly the same number visited each year for the past four years, and that count doesn’t include casual local visitors or people from neighboring towns. Cambronero says he is very proud that his model has turned out how he wanted it to be – a hub to attract children and amateur astronomers.

“Children love it,” Cambronero says. “What children want to do – adults also, all humans want to do – is touch. Everybody touches.” You learn by touching and explore by touching, he says. By getting up close to these gigantic spheres, by rotating them about their axes, by walking the distances between them, you come to understand the solar system better, he says.

It has been seven years since Cambronero’s daughter was that fifth-grader drawing a picture of the solar system, and, while her interest in science has waned, she was very excited about seeing the final model and is proud of her father. Cambronero says he will consider his model a success if it can influence the minds of a few children and keep them interested in the “beautiful wonders of nature.”

Images courtesy of Julián Gómez-Cambronero.