A star trek installed along the Mill Creek trail brings to light the vastness of the universe and our place in it

The three-quarter-mile SPACE WALK installation features illuminated, glow-in-the-dark models of the sun and planets at a scale of 3.5 billion to 1.

It’s late November in Cincinnati, which means some of us have pulled the covers over our heads and surrendered to months of barely glimpsing the sun. But there’s now a place to catch the orb shining even at night and feel connected to the universe, and other people, again.

SPACE WALK is a three-quarter-mile installation along the Mill Creek Greenway with illuminated, glow-in-the-dark models of the sun and planets. The scale for this linear solar system is 3.5 billion to 1. That ratio reduces the sun’s diameter to just 16 inches, but it’s a beacon even at that size.

At night, dozens of lights pulsate inside a plastic globe that has been coated with fiery shades of black-light paint and suspended from a pole near Salway Park’s playfields. Little luminous planets are mounted to the front of other solar-powered lampposts. When spotted on an evening drive down Spring Grove Avenue, the points of light look like starships over the horizon. They lure us in. 

SPACE WALK is Josiah Wolf’s space odyssey. The astronomy enthusiast received a $10,000 People’s Liberty grant last fall with his wife, Liz, and artist Matt Kotlarczyk, who put the couple in touch with fabricators. Months of testing construction materials and solar-powered LED black lights followed before SPACE WALK debuted on Labor Day. Wolf believes it is the world’s only outdoor model of a solar system that lights up when the actual sun sets.

SPACE WALK can be explored day or night, on your own or with a tour. The planets are enclosed in 16-inch glass-and-metal discs, for comparing their size to the sun. Peer at tiny Earth in the daytime and see your big reflection stare back. 

“I drive by during the day and see kids looking, and it’s a good feeling,” says Wolf, who lives nearby in Northside. 

But nighttime really is the right time, especially with Wolf’s commentary and a small group. 

“This project is about learning,” Wolf says, speaking about his own edification as much as ours. He mainly wants visitors to consider the vastness of the solar system and the centuries that humans have dedicated to understanding it, building upon the collective knowledge and passion of predecessors like Galileo and Einstein.

As an evening tour of approximately a dozen people gathers at the sun, Wolf informs us that at this scale, it would weigh 110 pounds, rather than 4.18 nonillion. Until we lose sight of the star on the way to Uranus and Neptune — sorry, Pluto isn’t included — Wolf reminds us to keep looking back for perspective about the scope of the universe. 

Each planet’s disc lists its actual distance from the sun. All the other details come from Wolf’s talk.

“I love to share (SPACE WALK), and I sometimes feel like a little kid in that regard,” he says. “If more people thought about the vastness, the world would be a better place and get away from the petty stuff.” 

Wolf’s interest in astronomy is recent. “I think I was more into dinosaurs as a kid,” the 40-year-old musician, drum instructor and bartender says. But he always liked math, and he enjoyed physics at Walnut Hills High School. Three years ago, he started reading about space, watched documentaries and got a telescope. 

To satisfy his curiosity, Wolf built a model of the solar system in his backyard, using household objects including a ball and a peppercorn mounted on old fence posts. “I know kids do this in elementary school, but I never did it,” he says. Liz used luminous paint to depict each planet’s features so they would shine at night under black light. 

Wolf started setting up his scale model in parks and walking friends through. Liz and others suggested they find funding for a permanent location, which led them to People’s Liberty.

The Wolfs next needed a site with the proper mix of exposure and isolation — plus a straight-enough path for viewing the sun from at least Saturn. They considered Smale Riverfront Park, Ault Park and Burnett Woods. Around the same time, Groundwork Cincinnati/Mill Creek, the nonprofit bringing the urban river corridor back to life, was looking for an art project. When the organization heard about SPACE WALK, the stars aligned.

“Like everything else we do, it’s multidimensional,” says Tanner Yess, Groundwork’s youth leader, field manager and trail coordinator. 

The nonprofit previously teamed with PAR-Projects and other artists on placemaking efforts such as a corn maze/community garden in order to introduce residents to the group’s broader goals of social and environmental justice. 

SPACE WALK is another way to reach people on different levels. Yess says its prominence increases awareness of Groundwork and the Mill Creek Greenway tenfold. 

“We’re going after that word, ‘greenway,’ ” Yess says of activities beyond monitoring the creek’s water quality. Urban trails open up opportunities for economic development in underserved communities, he says.

Yess praises SPACE WALK for being easy to understand, with a design that “catches and grabs” youths. 

“There are science lessons we can incorporate into education programs,” Yess says. “There’s math involved.” 

During tours, Wolf works that math into games. Before our group departs the sun and heads 53 feet to Mercury, he asks us to try to move about 4 inches per second — roughly the speed of a particle of light traveling from the sun at this scale. Real photons travel 3.5 billion times faster, or 186,000 miles per second. Three minutes later, we arrive at our first destination, where Wolf reminds us that when we view the most distant stars in the sky, we are seeing them as they looked years ago — only now is their light reaching Earth. 

The mini-planets appear exactly as if one side were lit by the sun. Wolf brings along a towel to wipe smudges left by folks who press their noses against the glass discs for a closer look. Liz, who decorated the Wolfs’ prototype, also painted the SPACE WALK sun, but this time she turned over the planetary detail to Cincinnati artist Steve Casino, who paints exquisite portraits on peanuts. 

As we move on, Wolf readily provides discoveries from space probes. He lists how many moons each planet has, opening a flap on the back of some discs to reveal a few of them. Because of the installation’s scale, it’s not feasible to show every one.

As we near Neptune and the end of the three-quarter-mile trek from the sun, Wolf pauses to remind us that the cosmos extend beyond what’s represented by this installation. Using SPACE WALK’s scale and its Northside location, Wolf places Voyager I — an interstellar explorer launched 39 years ago — in the vicinity of Findlay Market. The Oort cloud — the outer limit of our solar system — would lie 1,200 miles away, or about the distance from Cincinnati to Denver. The nearest star to our sun, Proxima Centauri, would be as far away as Korea and the size of a baseball. If the entire Milky Way were represented at this 3.5 billion-to-1 scale, the model would still span the vast space from the actual sun past Mars’ orbit. 

An apologetic Wolf worries that he’s longwinded, but his amateur status means he’s informative without being intimidating. Others on our walk freely start sharing what they’ve read about space. 

Wolf is a fan of astrophysicist Neil deGrasse Tyson and his Cosmos series, which explains space science to the layperson in a storytelling format. “NASA tries to make it cool, but it makes it less cool,” Wolf says. “They are speaking more to their peers, not visualizing in a step-by-step process.”

Wolf plans on at least another year along the Mill Creek and says he would love to host field trips. He brought a group of students from Walnut Hills High School through and heard that the school’s astronomy club is interested in a tour. He’s a little intimidated that the club members will know more about space than he does. “Yet, I’d love to be challenged,” he says. 

Groundwork has set up a partnership to collect donations for SPACE WALK maintenance (and to possibly have a spare sun on hand). Wolf is offering tours for up to 10 people as incentives for giving. 

Wolf also has considered enhancements such as an app for self-guided tours. “I could narrate it, get Neil deGrasse Tyson to narrate it,” he jokes.

But as much as Wolf likes to share information about the solar system, he also wants to keep SPACE WALK simple to maintain a mysterious feeling. Before the sounds of Interstate 75 and the glow of city lights intrude at the end of the installation and pull walkers’ heads out of the clouds, there are several peaceful stretches for scientific or spiritual contemplation.

“It blows me away that we’re here, evolved and don’t really understand why,” Wolf says. “We’re here to observe it all.”

A DIY Space Odyssey 


Welcome to the final frontier: a 3.5 billion-to-one scale model of the solar system running along the Mill Creek Greenway. The three-quarter-mile SPACE WALK installation features glow-in-the-dark replicas of the sun and eight planets — excluding Pluto — mounted to the fronts of solar-powered lampposts. While founder and astronomy enthusiast Josiah Wolf offers tours for up to 10 people, eager space voyagers are welcome to explore the expanse on their own. But don’t set out uninformed — go in armed with these facts and figures from Wolf regarding SPACE WALK’s scale.

  • If the sun were actually 16 inches — the size of SPACE WALK’s model — it would weigh approximately 110 pounds. Its actual weight? 1.989 x 10^30 kilograms — that’s basically a 2 with 30 zeros behind it.
  • Planets are placed in 16-inch cases, demonstrating the relative size of the sun in comparison to each planet. 
  • Look back at the sun each time you arrive at a new planet — that’s the size the actual sun would appear from that planet in space.
  • At this scale, the speed of light is about 4 inches per second. Its actual speed is 299,792,458 meters per second. Walking from the sun to Mercury at the speed of light takes approximately 3 minutes. 
  • The sun is 400 times larger than the moon, but also 400 times farther away, explaining why the two appear the same size in the sky. Place your right cheek against the glass encasing the model of Earth, look back toward the model of the sun and close your left eye; the sun and moon will appear to be the same size.
  • At SPACE WALK’s scale, the space between asteroids is about the length of an adult’s armspan. In reality, they are millions of miles apart, with the asteroid belt encircling the sun like an enormous donut. 
  • When you reach Neptune — the final planet on the walk — you’ve arrived at the inner edge of the Kuiper Belt, a circumstellar disc that lies beyond the planets in our solar system. If you were to continue walking up the Ludlow Viaduct to where Central Parkway begins, you would reach the outer edge of the Kuiper Belt. 
  • If you continue to walk a few miles south on Central Parkway to Findlay Market, you’ll illustrate the approximate distance of Voyager 1 — a space probe that is the farthest man-made object from Earth in the solar system — to the sun. 
  • Extending SPACE WALK’s 3.5 billion-to-one ratio beyond the installation, driving from the model sun to Denver, Colo. demonstrates the distance of the Oort Cloud — a theoretical bubble — from the sun. 
  • Flying from Cincinnati to South Korea corresponds to the approximate distance from the sun to the closest star in our galaxy, Proxima Centauri. At SPACE WALK’s scale, the red-dwarf star would be about the size of a baseball.

SPACE WALK begins at Salway Park, 4500 block of Spring Grove Avenue, Spring Grove Village, and ends near Old Ludlow in Northside. More info: spacewalkcincinnati.tumblr.com and groundworkcincinnati.org/spacewalk.

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