Only within the last decade have stargazers come to appreciate what residents of north-central Pennsylvania have long known: the night skies over Cherry Springs State Park are among the darkest anywhere in the eastern U.S.
Two sizable annual gatherings — the Cherry Springs Star Party (hosted by the Astronomical Society of Harrisburg, PA) and the Black Forest Star Party (Central Pennsylvania Observers) — help the area attract thousands of amateur astronomers annually.
So it's fitting that Cherry Springs was recently declared an International Dark-Sky Park, only the second site to earn this designation from the International Dark-Sky Association. The IDA announced its decision earlier this month at its 20th-anniversary meeting in Tucson, Arizona.
The Pennsylvania Department of Conservation and Natural Resources, which manages the park, had already become a leader in night-sky protection and appreciation. But to meet the IDA's stringent guidelines for a dark-sky sanctuary, additional steps were taken to ensure that those pristine black skies would stay that way.
For example, park staff retrofitted all outdoor lighting to be fully shielded and to utilize low-wattage compact-fluorescent bulbs. Some areas of the park were even cordoned off as "no-light zones" to protect nocturnal animals and to maximize the view above for amateur astronomers.
"This designation is continued validation that this region has something special to offer to our visitors," noted DCNR Secretary Michael DiBerardinis in a prepared statement. "We are proud of what we have protected, and hope our visitors will enjoy the remoteness of the Pennsylvania Wilds and Cherry Springs State Park for many years to come."
One modest threat to the park's darkness comes from a proposed cluster of several dozen wind turbines to be built nearby. Tower lighting to warn aircraft in the vicinity could degrade the view very slightly, depending on what kind of lighting system gets installed. Results from a study to assess and minimize the lights' impact were made public in late May, and you can access them here.
In late 2006 Gary Honis and Stan Stubbe of the Pennsylvania Outdoor Lighting Council prepared their own assessment, titled "Protecting the Night Sky Resource of Cherry Springs Dark Sky Park". Honis worries that the tower lights will become a problem for wide-field astrophotography.