Tuesday, Apr 10, 2007
Nearly 100,000 people stop at Natural Bridges National Monument in southeast Utah each year, but only a fraction of those visitors see its most spectacular vistas. âThatâs because you can only see them at night,â says Ralph Jones, chief ranger at the park.
Granted, the daytime landscapes at the national monument are particularly fetching, but the night sky? âAmazing,â says geologist and astrophotographer Terry Acomb.âThere is a tremendous contrast between the bright night sky of stars and the dark canyon wallsâ¦ Itâs just beautiful out there.â
The beauty of the night sky, the lack of light pollution, and the National Park Service commitment to night skies as a natural resource led the International Dark-Sky Association this spring to designate Natural Bridges National Monument as the worldâs first International Dark Sky Park.
âThis is one of the darkest national parks in the country,â Jones says, referring to a comprehensive study of night sky quality conducted by the National Park Service.
Just how dark is it? âItâs the only Bortle class 2 sky theyâve documented,â said Chris Luginbuhl of the U.S. Naval Observatory in Flagstaff, Arizona, and a board member of the International Dark-Sky Association. âIn plain English that means itâs the darkest or starriest sky theyâve seen while doing these reviews. The Bortle system is a 10-level scale with one and two being the darkest skies and 10 having the most light pollution.â
While the dark sky park designation is great, Jones says, âthe International Dark-Sky Associationâs Dark-Sky Park Program challenged Natural Bridges to minimize its own nocturnal impact and share the magnificent starry sky with park visitors.â
Responding to the challenge meant changing a lot of light bulbs. More than 80% of the light fixtures have been modified, making them dark sky-friendly by shielding them so all the light points downward.
Most of these outdoor fixtures utilize 13-watt compact fluorescent light bulbs that provide ample light but prevent stray light from the visitor center and park ranger residences from interfering with campgrounds and backcountry. Jones says the rest of the park lights will be upgraded in a few months.
On a clear night - and there are many each year in this dry, rugged land - the parkâs dreamy night sky reveals the Milky Way galaxy and a jillion or so stars and planets. Acomb, and other night sky photographers, have been to the park for years, capturing visits from interstellar celebrities like Comet Hale-Bopp. They donât see many other visitors and Jones says they donât expect a big rush even with the international designation.
During the summer, the park provides astronomy ranger programs under spectacular starry skies. âMany park visitors are astounded when they first see the Milky Way under a dark sky. It isnât just a faint smudge in the sky, but a bright, intricate river of lightâalmost three dimensional,â Jones says of the edge-on view of our own galaxy.
Starry skies are recognized by the National Park Service as part of the scenery of the park, and management guidelines encourage parks to minimize light pollution whenever possible.
The benefits go beyond stargazing; âNatural Bridges has reduced its operational costs and energy use by upgrading its outdoor lighting, creating a better habitat for nocturnal wildlife, and improving visibility and safety at night,â says park superintendent Corky Hays. âI hope our national parks can continue to provide a clear view of the heavens that so many of us have lost from our backyards.â
Further information:http://www.nps.gov/nabr and http://www2.nature.nps.gov/air/lightscapes or contact Chad Moore of the National Park Service Night Sky Team at 435-834-4904 or Ralph Jones at 435-692-1234 ext. 13. Information on the International Dark-Sky Association is available at http://www.darksky.org.