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Eight-year-old Lilli Prouty of St. Paul took on something a bit more ambitious than sidewalk chalk drawings to give neighbors something to look at while taking a walk.

Lilli created the solar system.

To illustrate the vastness of space, Lilli (with help from her parents) recently made a scale model of the solar system, putting up laminated signs in her neighborhood to demonstrate the relative distance between the sun and the planets.

Even at a scale of about 2.6 billion to one — with Earth the size of a popcorn kernel, Jupiter as big as a racquetball and the sun the size of an extra-large beach ball — Lilli’s solar system model spans nearly a mile and a half from her sun to her Pluto.

She’s invited her neighbors and other “fellow passengers in spaceship Earth” to travel to each planet on foot or bike in what she calls the City Space Walk.

“City Space Walk is a science project, a scavenger hunt, street art and a neighborhood experiment,” Lilli explains in a video about the project that her family made. Lilli and her mom, Julianna, appear in the video wearing astronaut costumes saved from last Halloween, and her dad, Bill Prouty, is behind the camera.

To keep urban explorers from getting lost in space, the Proutys have created a Google Maps link on their City Space Walk Facebook page that you can summon on your smartphone to guide you from planet to planet.

The signpost for the sun is located on a streetlight near Lilli’s school, St. Anthony Park Elementary School. The inner planets — Mercury, Venus, Earth and Mars — are within a block away.

Just beyond those, you can find the asteroid belt. But then things start to stretch out. Jupiter is near St. Anthony Park Library. Saturn is near Murray Middle School. Uranus is on the University of Minnesota St. Paul campus and Neptune is near the Minnesota State Fair grandstand.

“I’m of the generation where Pluto is still a planet,” said Bill Prouty, of the distant heavenly body that was recently reclassified as a “dwarf planet.”

So there’s a sign representing Pluto orbiting in the Como Park neighborhood.

Each of the planetary signs feature an image of the planet and fun facts about gravity, temperature, length of orbit, composition, moons and date of discovery.

There are also QR codes you can scan with your phone to lead you to your next stop or guide you back home.

The City Space Walk suggests you can have whole worlds in your hand in the correct scale by using a mustard seed for Mercury, a golf ball for Saturn and a penny for Neptune.

“The whole thing for us was a good way to do a science project for my daughter,” said Prouty. “We wanted to give folks an activity they can do as a group, to get outside and do some science.”

Prouty said the project was inspired by a similar, but smaller scale model of the solar system less than a half-mile long that the family saw on the National Mall in Washington, D.C.

“I learned the names of all the planets and their order,” Lilli said after the project was done.

She also said she enjoys monitoring the project’s websites to track the number of people who have viewed the solar system map (about 800 as of early last week).

Prouty owns a video production company that does a lot of TV commercial work, which explains why his video of the City Space Walk project, featuring hand-drawn animation, is so polished.

But Prouty has made creating the solar system easy for anyone.

The City Space Walk Facebook page includes a how-to video with instructions, links and downloads on how make signs and an online map and generate QR codes.

There’s even a link to a spreadsheet that will automatically calculate the relative size and distance between each planet so you can make your own neighborhood solar system as big or as little as you want.

“It’s basically some ratios,” Prouty said.

Lilli said that for her next project, “we are going to make a sun clock from the telephone pole shadow.”

Prouty also said he might add a sign that would show the relative location of the Voyager space probes that have now flown beyond the solar system. They’re as far away as downtown St. Paul in City Space Walk scale.

But to show the distance to Alpha Centauri, the nearest star to us, Prouty calculates he would have to put up a sign in Australia.

And that is a very long space walk indeed.