Keep Your Eyes on the Skies

by Bridget Baker

For nearly 60 years, the Peoria Astronomical Society has helped the celestially curious take a peek at the night skies.

Space… the final frontier. And so it has been for centuries, as man looks to the sky in wonder. Here in central Illinois, a group of amateur astronomers and curious observers have brought stargazing to the people for decades. With two observatories and regular meetings open to the public, the members of the Peoria Astronomical Society (PAS) are eager to open up the skies—so you too can experience the same sense of celestial awe.

Eric Clifton, past president and a member for more than 50 years, credits Rollin Van Zandt as the society’s cofounder and original driving force. Not only did Van Zandt, an assistant director of research at Caterpillar Inc., convince former Caterpillar Vice President Murray Baker to support the initial construction of Northmoor Observatory, he also found the telescope which still resides there… under the bleachers of the gymnasium in the old Field House at Bradley University.

Tale of Two Telescopes
The heart and soul of the Peoria Astronomical Society lies in its two observatories: Northmoor, located on Peoria’s Leo Donovan Golf Course, and the Decker-Grebner-Van Zandt Observatory at Jubilee College State Park, a dozen miles northwest of the city. Designed and constructed in the mid-1950s, Northmoor was the first observatory in the state to offer public viewings—and how its century-old telescope was acquired is quite a story.

The nine-inch refractor telescope was built in 1913 for the Springfield-based Illinois Watch Company. At the time, the company used the stars to calibrate its watchworks, housing an on-site observatory for that very purpose. The telescope’s body was manufactured by Gaertner Scientific of Chicago, and its lens was ground by Octave Leon Petitdidier—the same optician who ground lenses for Dr. A.A. Michelson, whose famous experiment to determine the speed of light won him the Nobel Prize. When the watch company closed its doors, Bradley University purchased the telescope with the intention of constructing its own observatory, but that project was abandoned when the Great Depression hit. For years, it lay dormant in storage before being rediscovered by Van Zandt.

In 1955, the telescope was reassembled and transported to Northmoor, where the PAS began offering free viewings to the public. “[It’s] a fantastic asset for Peoria and for our society,” says Nick Johnson, observatory director. “You just don’t see these every day.” Built with the assistance of the Peoria Park District, Caterpillar Inc. and numerous other companies, Northmoor underwent major renovations in 2009, with a new, rotating dome installed to replace the original, which had fallen into disrepair.

In 1974, the Decker-Grebner-Van Zandt Observatory at Jubilee was established on land donated by the late philanthropist William Rutherford of the Forest Park Foundation. With two domes, each housing a telescope, the site was chosen to escape the lights of Peoria, which had gradually encroached upon the once-dark skies at Northmoor as the city expanded northward.

The 24-inch Newtonian reflector telescope at Jubilee was built entirely by PAS members—no small feat. “In the late ‘70s and early ‘80s, the only way to get a big telescope was for a group to come together and build it,” Clifton explains. Facilitated by a large financial gift from Dr. Sam Decker, the task required nearly three years to complete. PAS members Art Grebner and Dan Joyce ground and polished its mirror, while Rollin Van Zandt and other society members designed and constructed the tube assembly and mount, and prepared the site. When it was finally mounted at Jubilee in 1980, it was the largest amateur-built telescope in Illinois.

Calling All Sky Watchers!
Just as many PAS members own their own telescopes, they encourage the celestially curious to explore the skies on their own. “You’d be amazed what you can do with these closet telescopes,” says Rich Tennis, PAS director at large, who built an observatory in his own Woodford County backyard, which he has fondly dubbed the “Star House.”

For those without their own equipment, however, the Peoria Astronomical Society’s passionate members are ready and willing to share their expertise. On Saturday nights from May through October, the society hosts free public viewings at Northmoor, with volunteers on hand to show amateur starwatchers the ropes, from how to operate their own telescopes to locating constellations and other celestial objects. It also offers free monthly telescope clinics, and both the Northmoor and Jubilee observatories are available for private viewings—just contact the society to plan your excursion.

Celestial Sightseeing
If you’re feeling inspired to browse the skies, here are a few objects to set your scopes on:

  • Earth’s moon—the best time to observe it is in the first or third quarter during a new or quarter moon phase—when it’s not as bright—so you can best see its craters and other surface features.
  • Saturn—the second largest planet in our solar system and furthest planet from Earth visible to the naked eye. The PAS says 2014 will be a great year to view Saturn.
  • Jupiter—the largest planet in our solar system. Its most extraordinary feature is the Great Red Spot, a hurricane-like storm that’s more than 300 years old and three times the diameter of Earth at its widest.
  • Hercules Star Cluster—discovered by Edmond Halley in 1714, the “celestial strongman” is about 25,000 light-years from Earth.
  • Andromeda Galaxy—the Milky Way’s nearest neighbor and the most distant object in the sky that can be seen unaided. Andromeda is 260,000 light years long and contains about a trillion stars.

But challenges lie ahead. Like many associations, the society’s membership is declining, as fewer young people sign on as members. Perhaps more significantly, Peoria’s steady expansion over the years has increased the problem of light pollution. As artificial light scatters through the atmosphere, it obscures the light from galaxies, nebulae and other distant objects, making them much more difficult to see than at “dark sky” locations. This issue is not unique to Peoria; in fact, an international “dark sky” movement has arisen to facilitate solutions and promote the value of dark, star-filled night skies.

Once considered a “dark sky” location, Northmoor now lies in the heart of the city, where there’s growing concern that continued growth could soon obscure the skies over Jubilee. The PAS has brought awareness to the issue with some success: when I-74 was overhauled a decade ago, it consulted IDOT on its decision to install lighting fixtures with covered tops directing light downward, which greatly improves efficiency and roadway visibility, as well as causing less light pollution. The City of Peoria has adopted similar policies to discourage light pollution; the new sports complex being on the north end will use the latest lighting technologies to minimize unwanted light pollution.

Even as it battles light pollution and works to increase membership, the society has never taken its eyes off the skies. Over the years, more than 45,000 people have observed the cosmos through the nine-inch refractor at Northmoor Observatory; for many, it’s a tradition that spans generations. “It’s common to run across people who grew up going to Northmoor and bring their kids, who then grow up and bring their kids,” Johnson says. “That’s what gets me the most. This is… a Peoria legacy. It’s one that people have and use and appreciate, and would be sad if it went away.”

The Peoria Astronomical Society hosts regular meetings in the planetarium at the Peoria Riverfront Museum. Northmoor Observatory is open to the public every cloudless Saturday night from May through October, with volunteers ready to assist in your discovery of the cosmos. Private groups can be scheduled at Northmoor or Jubilee at any time. For more information, visit