Dark skies Cherry Springs State Park

the trifid nebula (m20) in sagittarius, seen park

astronomers , stargazers appreciate cherry springs state park darkness , clarity of skies, make perhaps last best refuge of natural night sky in eastern half of united states. sky @ cherry springs has been classified 2 on bortle dark-sky scale, meaning has no light pollution. such dark, starry skies unavailable two-thirds of world s population, including 99 percent of people in continental u.s. , western europe . optimum conditions, 10,000 stars visible naked eye @ park, clouds appear black holes in starry sky, , milky way bright casts discernible shadow. in contrast, big city residents can see few dozen stars @ best, , in rural areas can typically see 2,000–3,000 stars. milky way cannot seen in eastern us, when there no moonlight obscure it.

the quality of night skies @ park , growing popularity stargazing result of several factors. cherry springs in midst of largely undeveloped 262,000-acre (106,000 ha) susquehannock state forest, , on summit 2,300 feet (701 m) above sea level. because on allegheny plateau, there no mountain peaks block sky, , astronomy field offers 360 degree unobstructed view. closest city williamsport, 60 miles (97 km) southeast. surrounding communities sit in deep valleys, intervening terrain screens of light produce; park has no artificial skyglow in direction. cherry springs fog-free , latitude puts in excellent position observe galactic center of milky way. remote location means there little commercial air traffic interfere astrophotography, while pa route 44 still offers relatively easy access park interstate 80.

in addition these natural factors, has been done intentionally make skies @ park clear , dark , keep them way. within park, former overhead electrical lines have been buried not obstruct views, lighting shielded, , white lights have been converted red, has least effect on night vision , astrophotography. light passing vehicles blocked earthen berms covered grass, or shrubbery , spruce trees; astronomy field gate has special light-blocking tarp. park s dark sky fund has paid many of these improvements since 1999.

two of park s 3 astronomy domes, walls prevent wind moving telescopes during observation

since 2006 acquisition of cherry springs airport, new public programming field has been established on former airstrip. field northeast of pa route 44 , intended educational programs or stargazing, not spend night. overnight observers , large telescopes use astronomy field southwest of highway. nighttime visitors may use flashlights red filters, , may point them @ ground. astronomy field has further restrictions on lights, , parts of park light-free zones.

to preserve dark skies @ cherry springs state park, tri-county rural electric company installs light-shielding caps on outdoor lights @ local homes free. in 2001 the pennsylvania general assembly passed outdoor lighting control act , both established park dark sky preserve , required minimal , shielded lighting @ new state facilities reduce light pollution. design guide pennsylvania wilds region, includes park, emphasizes importance of maintaining dark skies. dcnr spent $396,000 in june 2007 buy mineral rights under 1,980 acres (800 ha) of park , state forest prevent natural gas drilling , associated development there.

a wind farm has been proposed on site 13.7 miles (22.0 km) park. in 2008 potter county passed ordinance wind turbine lights shall not interfere state-designated dark skies preserve @ cherry springs state park . same year dcnr commissioned study on wind farm s impact, concluded red warning lights on wind turbines not impact darkness of sky , directly visible astronomy field under rare conditions. others in astronomy community challenged these conclusions , feared new lights on several dozen wind turbines near park degrade observations , astrophotography. study recommended dcnr shield , redirect lights @ nearby denton hill state park downhill ski area make sky darker @ cherry springs.