D e s e r t E x p o s u r e
June
2009
Starry, Starry Nights
Celebrating southern New Mexico's endangered dark skies, in the 400th anniversary of modern astronomy. |
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SIDEBAR: Sharing New Mexico's Skies |
By Gary Emerson and Kathy Anderson
It's a sad fact that most Americans living on Planet Earth today have never experienced a truly clear, dark, night sky. Data shows that two-thirds of humanity live under too-bright night skies and have never seen the vast majority of the planets and stars out there. One-fifth can no longer see the Milky Way. And, if unshielded night lights continue to grow in number, it's likely the Milky Way will disappear from sight for most of the rest of the world.
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North America at night: Department
of Dedense imagery |
The spread of perpetual nighttime twilight over the planet has reached critical mass, suppressing our ability to see the universe. The loss of true, dark night has led some to warn of damage to global biodiversity, the extinction of bird and mammal species, and even growing cancer risks.
The 1997 Department of Defense image of night-sky emissions shown here will look much worse when updated in about 18 months. The majority of US light is emitted east of the 100th meridian, or east of central Kansas.
The image of the Silver City area shown here, taken by the Department of Defense nearly 15 years ago, shows the eastern half of Arizona, all of New Mexico, and the western half of Texas. The white line across the bottom is the border with Mexico. Silver City is the small blue-bordered double bubble of yellow light just below the center of the black area in the near dead-center of the image. For numerous reasons, Silver City's bright circle likely will be much bigger when an update to this image is released.
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City lights: Phoenix and Tuscon at
left; El Paso at right; Silver City and environs inside the yellow box. |
Phoenix is the largest multi-color area in the central left in the photo, with Tucson's lights connected directly to the southeast, followed by the lights of Nogales, Mexico, and Douglas, Arizona, along with other smaller settlements. This area represents some of the worst light pollution in the United States. The interesting fact about Tucson, however, is that its population density is on par with that of Phoenix, yet because Tucson has adopted corrective programs, it emits a much smaller glow.
El Paso is the largest multi-colored area to the lower right. Albuquerque, Santa Fe and Taos are located to the upper right. The connected bubbles of light starting in the central Albuquerque area and continuing to the northeast are along the Interstate 40 corridor on the way to Grants.
By way of putting this data on the ground, so to speak, people living in the bright white centers of these bubbles live in perpetual twilight at night. Residents rarely see the stars, might see a couple of the planets, and can see a not-so-bright full moon. Skies for those living in the areas of the red circles are not much better. The gold circles, surrounded by the green, are slightly better, and might allow viewing certain objects with the naked eye, depending on atmospheric particulates, smog and smoke. The blue areas might allow telescopic viewing of certain objects — on a clear, clean night.
By contrast, southern New Mexico skies, while not the best, favorably compare with the darkest of all skies on Planet Earth. The darkest-sky locations tend to be mountaintops on islands surrounded by ocean, such as Mauna Kea on the island of Hawaii and Roque de los Muchachos in the Canary Islands. After these locations come the high dry deserts of South America, the Australian Outback, and the deserts of Central Africa. Locations such as southwest Texas and central Nevada, followed by southwest New Mexico, are the next darkest sky areas. All of these sites are what we refer to as "true, natural, dark skies." The skies appear as they would if there were no artificial lights on Earth. That's attractive to astronomers.
The astronomers settled in the Cloudcroft area in the 1970s. The high elevation and dark-sky town ordinance there brought Cloudcroft international recognition as an astronomy viewing base. The town developed revenue streams through tourism as folks visited the nearby Sunspot Solar and Apache Point Observatories. Dark skies continue to be popular there today, although the lights of Alamogordo and El Paso now infringe.
Having fewer artificial night lights is not the only reason certain areas here are sought out by astronomers. Some of our dark-sky benefit is derived from lower moisture and fewer airborne particulates. Organizations such as the National Park Service monitor night sky visibility in most of the United States and their data confirm that some of the best night skies in the US are right here.
Silver City is no slacker when it comes to having relatively good night skies. Cloudcroft may have its Lincoln National Forest, but we have the Gila. The newly incorporated Silver City Astronomical Society has conducted dark-sky surveys here by using sky-brightness photometers to obtain quantitative data on the brightness of local skies. The society is comparing it to the best sites in the world.
The news so far is good: We have true, clear, dark skies, visible from the ground just 15 miles in any direction from downtown Silver City. For example, not far outside Silver City to the northwest, one can see an average distance of about 138 miles. In the eastern states and in most areas up north, folks only can see up to about 40 miles — and that's on a good night, with no clouds, no moon, no smog and no dust.
Many Astronomical Society members specifically chose Silver City in which to live because of our dark skies. They've made major life decisions to build homes and observatories here, bringing millions of dollars to the local economy. They contribute to local companies, nonprofit organizations and others through their volunteer efforts and donations.
The first astronomers who settled here, thanks to recently available technology or that created by them, have built at least two astronomical observatories that can be remotely operated from anywhere in the world. All one has to do is sign up on a website, choose an observation time, and the telescope "obeys," rendering highly valued data.
One of these telescopes is extensively used by students and astronomers alike. High school students in the Silver City area use it, as well as doctoral candidates attending universities all over the country. Silver City, as a base for serious astronomy, is "on the map."
The NFO observatory near Silver City has produced hundreds of thousands of images for research on minor planets and for use by students who use their own computers to take images for school projects. In 2007, co-author Gary Emerson's Tyrone Observatory obtained the largest image data in history on the minor planet Vesta, in support of the NASA space mission DAWN.
Southern New Mexico night skies produce revenue streams in ways not readily apparent, even to local astronomers. Establishments such as a night sky observers' bed and breakfast have been built not far from here. There, lodgers may bring their own telescopes or rent one from the owners. Guests sleep in quiet, dark, day-time rooms, have nice accommodations, and may eat a meal or two, enjoying New Mexico. There currently are three astronomy-friendly beds and breakfasts in the state — Casitas de Gila in Gila, New Mexico Skies in Mayhill and Adobe & Stars in Taos — with another being built. Two New Mexicans, Peter Lipscomb and Geoff Goins, have an enterprise in which they travel to B&Bs to present programs. Another new business targets the RVer and tent camper crowds in search of dark skies.
Sadly, the number of unshielded, upward-pointing lights in Silver City and the three miles around it is increasing every year. The lights of Lordsburg and Deming, El Paso, Tucson and the Interstate 25 corridor of central New Mexico are increasing.
Let's put this into historical perspective. This year, we are celebrating the 400th anniversary of modern astronomy. It was 400 years ago that Galileo Galilei (1564-1642) first used a telescope to look at the sky and German astronomer Johannes Kepler (1571-1630) published his Astronomia Nova. Dutch astronomer and physicist Christian Huygens (1629-1695) is also being honored this year for the publication of his Systema Saturnium 350 years ago, in 1659.
In Galileo's time, 400 years ago, the residents of Europe saw a Milky Way that was so blindingly bright, it cast clear and sharp shadows on the ground. The very few people who have seen something akin to that today have had to travel to one of the few places on the planet mentioned earlier.
In just the 10 years between 1982 and 1992, more than 19,000 square miles of rural cropland and wilderness in the United States were completely consumed by urbanization and "lighting up." Amazingly, that's equivalent to converting half of the state of Ohio into one big subdivision in just 10 years. The same sort of thing is happening here in New Mexico.
The damage from losing dark skies is not just to astronomy. In just the past five years of study, doctors have learned that sleeping in perpetual nighttime twilight can affect your health. Research done by Itai Kloog of the University of Haifa, Richard Stevens, a cancer epidemiologist and professor at the University of Connecticut, and others shows a very clear connection between nighttime artificial lighting and an increase in breast cancer among women. The more an area was lit up at night, the higher the incidence of breast cancer among that population. Researchers also found that the incidence of prostate cancer among men went up by at least 30%. Scientists have also suggested a link between childhood leukemia incidence and nighttime artificial light.