Twenty years ago, during a partial solar eclipse, members of the group North Georgia Astronomers were discussing the way the moon appeared to be close in size to the sun, but they knew that the sun was far larger than the moon. In fact, more than 64 million moons could be placed inside the sun if it were hollow.

But the astronomers soon realized that it was extremely difficult to comprehend this colossal difference in size. In the shadows of that solar event, they came up with an idea: create a scale model of the solar system and arrange representations of the planets along a trail to provide a sense of the system’s enormity, as well as the different sizes of the planets.

Soon, the group worked out a plan for the model, including sponsors, funding and a location that placed the sun at Gainesville Square and extended the planets along the city’s parks for 1.8 miles to arrive at Pluto near Lake Lanier. (While Pluto is not considered a planet anymore, it was at the time the attraction was conceived.)

The installation of the first station of the tour, a tiny quarter-inch piece of blue lapis lazuli stone representing Earth, launched the North Georgia Astronomers’ Millennium Project on Dec. 31, 1999. Two days later, Mercury, Venus and Mars were installed at the appropriate distances from the sun, represented by a 27-and-a-half-inch stainless-steel globe installed about a year later, at the corner of Spring and Bradford streets. A map showing the positions of each of the planet markers is available at the Gainesville Visitors Center, located at 117 Jesse Jewell Parkway.

Visitors should start at the beginning, with the big sun at the center of the solar system.  Walk along the square to visit Mercury, Venus and Earth, and then into the parks, tracking each planet as you go with the visitors center’s map. Each planet’s model is a globe built exactly to scale and is posted on a granite stand with a brief description.    The designers also spaced the planets along the trails to scale, in order to give visitors a sense of the terrific distances between the planets, along with their relative sizes.

Representing the largest body in the asteroid belt between Mars and Jupiter is a tiny bead of only 0.018 inches depicting Ceres, which had a brief moment as a planet in the early 19th Century. The model of Pluto includes an arrow pointing toward Alpha Centauri, which would be located another 12,500 miles away.

“If people walk the trail and give themselves time to think about it, the model really gives a sense of how small and isolated Earth is,” said Richard Webb, a retired astronomy educator and one of the trail’s original designers. “Everyone knows, more or less, the facts about the solar system, but the scale model puts you in a position to have an epiphany about where Earth fits into the system. If humans don’t make it here on Earth, we’re not going to make it. Once you have a moment like that, it changes you.”

The trails you walk along the way are leafy and peaceful, and the planets are not always immediately visible from the trails, creating a kind of adventurous treasure hunt. About 200,000 visitors come walk along the planets each year, according to Regina Dyer, the Convention and Visitors Bureau manager for the city of Gainesville.   

Along the same trails, the city has also installed a “Storybook Trail,” in which youngsters can read pages of a book on granite stands posted at different sites.  

You and your crew might build up an appetite taking in the cosmic voyage of the Millennium Project, and downtown Gainesville has plenty of restaurants within walking distance of the square. If you want to return to the decade when space first entered public consciousness, go to the Collegiate Grill, half a block from the square at 220 Main St., for burgers, hot dogs, fries and milkshakes in an authentic early-’60s malt-shop environment. And if you’re up for another attraction, the Northeast Georgia History Center a half-mile away offers exhibits on Native Americans and World War I, as well as a folk art gallery.