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Space Topics: Planetary AnalogsStars Above, Earth BelowAstronomy and Space Exploration in America's National Parks
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Dark Ranger Kevin Poe
Park Ranger ("Dark Ranger") Kevin Poe amid the telescopes used by the night sky staff at Bryce Canyon National Park. Credit: National Park Service |
Kevin ended his talk with a discussion of light pollution and why the parks are some of the last remaining dark-sky sites that the public can get to without a four-wheel vehicle. Since I have seen firsthand the growth of light pollution as the population around the famed Palomar Observatory has exploded in the last 15 years, this last part struck a nerve in me. Watching the crowd’s passion for astronomy on a cloudy night in Yosemite and seeing what the park service was doing to monitor and preserve their dark skies, I realized that the parks are a vast, largely untapped resource for astronomy education and outreach in this country.
Since that night I have been in regular contact with park ranger Chad Moore at Bryce Canyon National Park in southern Utah. He is head of the park service’s Night Sky Team, which is traveling through the national park system making observations at various places within the different parks to measure the quality of the darkness at each site. These observations consist of a computer-driven, off-the-shelf CCD and camera lens that photographs the entire sky over the course of less than 40 minutes through a single-color visible light filter. This filter is similar to astronomers’ Johnson V-band filter so that the data they produce is easily used by astronomers. In addition, the central wavelength of about 550 nanometers is very close to the dark-adapted human eye, so the images are easily understood in terms of what a typical person would see.
The light-polluted sky over Joshua Tree National Park
An all-sky image of the sky over Joshua Tree National Park. Brightnesses per square arcsecond increase from blue to white. Notice the faint light-blue structure of the Milky Way overhead almost lost in the glare of southern California lights. Credit: Dan Duriscoe, NPS |
The dark sky over Natural Bridges National Park
Natural Bridges National Park has been named the world's first dark-sky park. The brightest feature visible from the park was the center of our galaxy in the lower left. This is how every sky used to look. Credit: D. Duriscoe and C. Duriscoe, NPS |
Dan Duriscoe, park ranger at Death Valley National Park, makes the observations and is a real artist in working with the images. The panoramic image of the Milky Way over Yosemite Valley that appears on the Introduction of this blog is an example of what he can do with the data from this system. With these all-sky images the Night Sky Team is able to quantify the quality of the skies above the parks as well as identify and quantify the sources and amount of light pollution. Their preliminary results were published in the Publications of the Astronomical Society of the Pacific this last spring (a version of their paper is available on-line at the Astro-ph paper repository website). Their data is available on-line at their National Park Service website.
This last week I returned from a quick trip to Bryce to meet with Chad and members of the astronomy program there, Angie Richman and Kevin Poe (who is still giving a version of that excellent talk). Their goals are to get the U.S. public to appreciate dark skies, care that they are disappearing, and thus motivate them to action in order to preserve them. They’ve convinced the Department of the Interior (of which the NPS is a part) to care about this goal as well.
Chad expressed his view to me that it is ironic that at the moment in time when the human race is finally moving out into the universe (both in person and with robotic probes), we are fast turning our atmosphere opaque to starlight, so that soon we will have no firsthand connection to that universe. It occurred to me that as astronomers and planetary scientists my colleagues and I should be very concerned about this. We have the privilege of doing what we love and exploring other worlds because the governments of this planet support us financially (both in paychecks and payloads). If the day comes when the last star disappears into the nighttime glow, and the last person stops looking up because they have forgotten there is a universe out there beyond the atmosphere, how long will the public continue to support our exploration or feel that it has any personal relevance to their lives?
Chad estimates that nearly 30 thousand people attend night-sky programs at Bryce Canyon annually. And this is just one of the many parks that offer some kind of night sky program. Each June they hold a star party under the darkest skies I’ve ever seen. During my trip, standing amid the throng of people looking through telescopes set up at the visitor center I saw parts of the Milky Way I’d never seen before with the naked eye. Next June, in what will be the last stop on my year-long trip to pursue astronomy in the parks, I will be returning for three weeks to help with the 8th annual Bryce Canyon Star Festival. Given the initial motivations for the project, it will be a fitting place to end this part of the project before moving on with the next part.
Now, however, I am off to get ready for the first five-week leg of my trip through Rocky Mountain, Grand Tetons, and Glacier National Parks. My next entry will take place in two weeks from Rocky Mountain National Park (or wherever the nearest wireless hotspot is) and will begin the discussion of terrestrial analogs.
The Milky Way from Bryce Canyon
The summer Milky Way sets over the rim of Bryce Canyon as seen from the Sunset Point overlook. The image is a mosaic of six frames taken using a simple camera and tripod. Each exposure was 60 seconds long with a Canon 20Da camera set to ISO 3200, and a 28mm lens at f/2.8. The only illumination to the canyon rim is from the Milky Way itself. Credit: Tyler Nordgren |
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