A basic-level summary is provided of work since late 1993 to control light pollution in Chile. The purpose of this article is to stimulate such work inside Chile and to promote good lighting in developing countries in general. Chile is selected as the case study because of its critical importance to optical and radio astronomy, and the related economic and cultural benefits for Chile and the world. Examples are presented in some detail in order to illustrate adjustments that have been made to accommodate local scientific, cultural and economic realities and to show that it is necessary to anticipate the issues involved in controlling light pollution several decades before it would otherwise become a problem. It is hoped that international organizations such as the IAU, the IDA and the CIE can soon promote programs in Chile that can serve as pilot programs for other parts of the developing world.
I was invited by the organizers of this Symposium to give a presentation on "The Importance of Ground-Based Optical Astronomy" suitable for lighting engineers and astronomers. The opening remarks by speaker after speaker emphasized the key scientific, economic and cultural aspects of ancient and modern astronomy. Being unwilling to dissociate ground-based from space-based astronomy or optical- from radio- and millimeter-wave astronomy, my talk emphasized the importance of ground-based astronomy within this wider, integrated context.
The scientific importance of astrophysics as a laboratory of extreme conditions, e.g. in solar flares, planetary nebulae, supernovae, the nuclei of galaxies, gamma-ray bursters, black holes and the big bang is known to all physicists and astronomers.
Its cultural importance in terms of understanding our origins and eventual fate - is well known to all. Well-written and authoritative treatments of these matters at the level of a general reader can be found in books on cosmology such as those by Weinberg, 1993, Hawking, 1988 and Rees, 1997).
The economic and cultural importance, over the centuries, of knowledge of the seasons, navigation, gravity, nuclear energy and so forth is obvious. Practical spin-offs from modern astronomical technology include such diverse areas as advances in medical x-ray technology, breast-cancer diagnosis, monitoring of the structural integrity of oil rigs and the avoidance of waste light energy from cities.
However, following the various discussions at the Symposium, it became clear that a volume like this would be more useful if it contained some discussion of the issues involved in preserving the astronomical sky - as they arise today in Chile. This is because Chile is at the center of the greatest construction program ever undertaken in ground-based astronomy, so the scientific, economic and cultural importance of its astronomical sky is obvious and increasing. Chile also provides examples of issues associated with controlling light pollution in a developing country.
The preservation of the astronomical skies over Chile is a concern for everyone - and an appropriate issue, therefore, for the IAU and other international bodies (such as the UN, UNESCO, the Commission Internationale d'Eclairage and the International Dark-Sky Association), as well as for Chile's own national and regional authorities.
Astronomy has, over the years, found it possible to run further and further away from industrialized areas in order to be able to work under skies unpolluted by man-made intereference. Other, more qualified speakers addressed the issue of radio interference; with the advent of the Atacama Large Millimeter Array (ALMA), control of such interference is obviously vital to international astronomy and to the economics of that region of Chile. This basic-level article will be focussed on optical interference - primarily the increase over natural sky background produced by light from surrounding communities and industries.
Seven telescopes larger than 6m in diameter are currently being brought into regular scientific use in northern Chile or are nearing their final stages of construction and commissioning. The four 8m elements of the European Southern Observatory's Very Large Telescope on Cerro Paranal, the Carnegie Institute of Washington's twin 6.5m Magellan telescopes on Cerro Las Campanas and the international 8m Gemini South telescope on Cerro Pachón will all depend, for their success, on the skies over northern Chile being preserved in their current pristine condition. New generations of large, wide-field, survey telescopes such as the VLT 2.65m Survey Telescope (VST), the British 4m VISTA telescope and the US 8m Dark-Matter Telescope are being built or proposed specifically to take advantage of the darkest available skies.
Examples of the kinds of science that need such dark skies cover the full range of size and distance in the universe - from the detection of large-scale structure by means of weak gravitational lensing of faint galaxies to the early location and study of near-earth objects (asteriods and comets).
To set a context for the goal of the efforts to preserve these dark astronomical skies, the natural sky background at the zenith varies by a factor of about 1.7, i.e. by about 0.m6, 21.3<V<21.9 magnitudes per sq. arcsec over the course of the 11-year solar activity cycle (Krisciunas, 1997). Faint galaxies will be observed with telescopes in Chile down to surface brightness levels at or even below ~29 mag per sq arcsec, i.e. ~700 times fainter than the natural solar-minimum background at V. Our goal must be to ensure that artificial light does not increase the natural sky background by more than the typical measuring error of about 0.1 to 0.15 magnitudes per arcsec at these levels of surface brightness, at least in broad passbands (Kriscuinas, 1997).
AURA's observatory is the closest major observatory in Chile to city lights. It is therefore a natural point from which to lead an effort to study, and control light pollution, well before it can become a serious problem at Cerro Pachón and Cerro Tololo.
The measured sky brightness at the zenith at Cerro Tololo is <0.m08 brighter than the natural value, i.e. it is not yet possible to measure any artificial light pollution at zenith distances <45 degrees through broad-band filters (see, e.g. Walker and Smith, 1999). The sky overhead at Cerro Tololo and Cerro Pachon is still very dark.
Nevertheless, the ability to detect the sodium lights of La Serena spectroscopically by looking low in the sky in the direction of that city is an early warning that action that started in earnest in late 1993 has to continue, especially as such action has implications for astronomy throughout Chile. It may be possible to detect such radiation in certain directions low over the horizon from other major observatories in Chile. This should be attempted now at all of the major optical observatories (both in Chile and elsewhere) and monitored regularly. As discussed in section 5.1, it has already taken nearly 6 years to secure a set of government lighting regulations that can now be taken to local municipalities for communication, education, development of municipal ordinances and eventual enforcement. It is necessary to anticipate the issues involved in controlling light pollution several decades before it would otherwise become a problem.
The current boom in construction of international astronomical facilities in the north of Chile involves investments already surpassing a billion dollars. Specific plans exist which take this figure to well over US$1.2Bn. The detailed budgets for the observatories involved are, unfortunately, not readily available. Nevertheless, from experience, one can make rough estimates for the level of investment made in the Chilean economy. These lead to averages of about US$60M per annum entering the economy for construction and a steady ramp-up to about US$40M of annual investment in operations.
The Chilean national economy thus receives about US$100M in annual income from astronomy. Chilean astronomers are, in addition, awarded 10% of the observing time on telescopes in Chile. In return, the Chilean government provides a variety of privileges and tax breaks to the international astronomical community, and is generally supportive of astronomical development and the associated benefits arising from this foreign investment.
The AURA Observatory in Chile (Gemini South, SOAR and the telescopes on Cerro Tololo) provides a measure of the economic stimulus that occurs at a regional level. AURA has brought approximately US$150M in construction projects to Chile's IVth region and currently spends about US$4M dollars each year in Chile on operations. From 2002 onwards, with the arrival of Gemini South and SOAR, AURA will be spending about US$7M per annum in Chile. AURA has also stimulated local entrepreneurial activity in astronomical tourism, education and research as described in more detail in section 5.
We have seen that Chile has a strong economic interest in preserving the astronomical sky. Further beneficial economic and environmental impact arises from the potential for more rational use of energy in exterior lighting. As we have heard elsewhere at this conference, the United States shines well over US$1Bn of light annually into the heavens, while each year Japan inadvertantly sends about US$200M dollars worth of light into the sky
It will be interesting over the next few years to obtain and use unsaturated Defense Meteorological Satellite Program (DMSP) data from the National Geographic Society's databank (see papers by Isobe, Cinzano, and by Luginbuhl at this conference and elsewhere???) to measure the upwardly-directed light from Chilean cities and towns, including those nearest the major observatories. It will also be interesting to see the reaction of authorities in developing countries when informed of the flux in wasted currency from their major cities, along with reasonably simple guidelines in their own language about what can be done to reduce the waste.
Early DMSP data were taken at high gain. The data from large cities were saturated. Unsaturated data from the DMSP may, however, be available from the outset for smaller, isolated towns - such as those near major observatories. It would be interesting to see if sufficient precision can be obtained to monitor changes in the upward flux as remedial lighting programs come into effect.
Chile is beginning to realise the potential for eco-tourism based on its dark skies. The Servicio Nacional de Turismo (SERNATUR) has recently produced a 57-page full-color booklet on astronomical tourism in the province of Elqui (where AURA has its observatory). In combination with the municipal observatory described in section 4.3, they are generating sufficient funds from publicizing the dark skies in the region to support a growing tourist industry.
Several speakers at the Symposium mentioned the ancient cultural links in many parts of the world between astronomy, different religions and practical pusuits such as agriculture and navigation. In addition to the cultural impact of the tourism mentioned above, astronomy provides mankind with a sense of perspective on our place in the universe on our tiny island planet.
At this time, the Polynesian Voyaging Society's canoe "Hokule'a" (Arcturus) is sailing to Rapa Nui - Easter Island (the most westerly part of Chile). This journey is the culmination of a 25-year-long series of voyages by PVS's canoes across Polynesia; these voyages have led a cultural renaissance in the region. This latest voyage will close the Polynesian Triangle, formed by New Zealand, Hawai'i and Easter Island. The seas (away from the squid fleets - Sullivan 199x) offer dark skies to the navigators.
To quote from the PVS web page, "To get from Hawai'i to Rapa Nui, Hokule'a must travel.., 2820 nautical miles south (from 20 degrees N to 27 degrees S) and 2760 nautical miles east (from 155 degrees W to 109 degrees). The first three destinations (Nukuhiva, Mangareva and Rapa Nui) lie upwind of the departure points, so the canoe will have to struggle to get east against the prevailing winds."
"The sail from Mangareva to Rapa Nui will be the most difficult, as Rapa Nui lies 1450 miles to the east of Magareva...On this leg, Hokul'ea will be navigated without instruments by a team of Hawai'i's best navigators, headed by Nainoa Thompson. They will guide the canoe by celestial bodies (sun, moon, planets and stars), ocean swells...."
These bold navigators use astronomy in their endeavors and convey the wisdom of the more successful island peoples about the environment. The earth, too, is a tiny, isolated island.
At about the time of IAU Symposium 196, Chile's President Eduardo Frei Ruiz-Tagle signed the "Norma Luminica" which gives the force of law to a set of lighting regulations covering the IInd, IIIrd and IVth regions of (Northern) Chile. Cerro Paranal is in the IInd region. Cerro La Campanas is in the IIIrd region. Cerro La Silla, Cerro Tololo and Cerro Pachón are all in the IVth region. This code is currently being translated into English and will be available on the world-wide web by the time this article is published.
This set of national regulations provides a framework which allows us now to start serious work with municipalities in Chile, with the aim of mitigating and controlling light pollution. The President of the IVth Chapter of the Chilean Association of Municipalities (which includes those closest to AURA's Observatory) has recently and publically expressed a wish to help in this effort in specific and significant ways. These include supporting CONAMA's proposed program of educational seminars on the "Norma Luminica" and a series of site visits for key, local, public-works personnel. These visits will include lighting projects, Sr. Piraino's illumination-engineering laboratory at the Universidad Catolica de Valparaiso and visits to the AURA Observatory.
Initial efforts to capture the attention and support of local municipalities did not go well. The initial reaction was that changing exterior light fixtures would be too expensive, that tourism was flourishing as a result of the bright lights along the beaches and that there were concerns to ensure security at night. Although we used the correct reasoning and examples provided by the IDA, we did not make progress until a couple of amateur astronomers from Vicuña contacted us (Sres. Eduardo Valenzuela and Sr. Sergio Pizarro). Vicuña is the second-closest town to Cerro Tololo and Cerro Pachón, with a central population of about 9,000 (excluding outlying regions) at line-of-sight distances of roughly 18km and 23km from Tololo and Pachón. As luck would have it, municipalities in Chile were being offered the chance to apply for a loan from the central government to replace the old, inefficient, mercury fixtures with energy-efficient, sodium fixtures. The two amateurs asked us to help the municipality design the fixtures in such a way as to minimize running costs (in particular) and minimize the impact on the astronomical research going on nearby! This was the breakthrough we were looking for.
We first studied the situation in the USA, with the help of the IDA materials and Dave Crawford's personal advice. We soon realized that what works in the United States of America may not satisfy Vicuña's requirements. At that time there was only one supplier of low-pressure sodium lamps in the country. Such fixtures were too expensive for most Chilean municipalities because of losses to vandalism. High-pressure lamps have a wider market and are therefore available in Chile at lower capital cost.
We then made contact with Sr. Enrique Piraino, a lighting engineer from the Universidad Catolica de Valparaiso, who runs a laboratory used to measure and standardize Chilean lighting fixtures available on the Chilean market. Sr. Piraino provided consultant services to the Municipality of Vicuña (at AURA expense) in order to replace and reposition the town's street lights. This included replacing all the white-light globes which lit the town's main street, the "Avenida de las Delicias". The first step was to draw up an inventory of all existing street lights in the town (exisiting inventories were so inaccurate as to be useless). Powerful (400W) full-cutoff fixtures were used to illuminate the perimeter of the town square. 150W fixtures were used for the main streets near the center of town. Remaining streets were lit with 70W fixtures, all high-pressure sodium.
A rough calculation shows that the lighting change and redesign saves Vicuña nearly half of its municipal lighting bill. 1534 light fixtures were changed or modified. Illumination increased from 7.8M lumens to 8.9M lumens. Estimated power consumption dropped from 210kW to 110kW, with consequent large savings. Estimated power consumed in illuminating the sky dropped from 24kW to just over 1kW. The capital cost of the modernization has already been paid off from these savings and the municipality is delighted.
In recognition of Vicuña's seminal co-operation, the US National Science Foundation, at AURA's recommendation, donated a 30cm commercially-made telescope to Vicuña as the centerpiece of a municipal observatory. The town found the land, installed a 4km-long road, provided power, water and a building (which did not get funding from the Chilean science foundation, CONICYT - but did get a large grant from the Chilean National Fund for Art and Culture in addition to local, commercial sponsorship). Cerro Tololo provided an obsolete dome that was in good condition.
AURA staff provided the first course of lectures and practical workshops to members of the local community. Graduates of this first course then taught the second course in the series, so that the town now has people qualified to help visitors in various aspects of the observatory.
The new Cerro Mamalluca Municipal Observatory is now making sufficient money from tourism ("come to the darkest, clearest skies in the world") and conferences to be almost self sufficient and, with the help of government grants, will shortly be buying several new telescopes of its own. Phase I, the telescope, building and dome is in regular operation, every clear night. Phase II, containing a restaurant and a platform for amateur telescopes is nearly complete. A small-telescope educational and dark-sky research facility is at the proposal stage for Phase III; funds for this third phase are expected to be awarded next year.
Vicuña has worked closely with AURA to become a demonstration community allowing us to present a way to develop a mutually-beneficial community-wide business approach to the provision of good lighting. Once the cost of international broad-band links drops sufficiently, we hope to extend this work to include connection between schools in Chile and those in other countries (initially from the Gemini and SOAR consortium partnerships). Among plans being discussed are the production of a CD or video, in spanish, on the subject of light pollution, using illustrations of lighting in the region. This work is likely to be done in close collaboration with M. Metaxas (see paper at this conference).
The nearest town to the AURA Observatory in Chile is Andacollo, at a distance of only 28km. from Cerro Tololo and 33.5km from Cerro Pachón. Although it has only ~12,000 inhabitants, two international open-pit mines have opened there in the last five years. Fortunately, the lack of vandalism in the controlled area of a mine allows the mine to make economic use of the most energy efficient low-pressure sodium lighting. The mine needs powerful lighting for safe operation; the potential for significant light pollution from such a nearby source, particularly during the early phases of the project, was serious. Fortunately the mine was looking for opportunities to improve its rather tarnished environmental reputation and worked closely with us to direct its lights away from the line of sight to the observatory. We even identified troublesome individual fixtures for them on the telephone, as they kindly switched their lights off and on for us, one by one.
The nearest cities form the coastal conurbation of La Serena and Coquimbo, at a distance of approximately 49 km from Cerro Tololo (and approximately 58 km from Cerro Pachón and containing about 292,000 inhabitants. Chile's recent economic boom has increased the estimated output of light per inhabitant to levels similar to those in industrialised nations. Fortunately, both La Serena and Coquimbo are largely hidden from direct view from Cerro Tololo and Cerro Pachón by a range of mountains paralleling the coastline just a few kilometers from the shore. The arrival of bright lights, especially those along the beach drive (the "Avenida del Mar") has provided an undeniable stimulus to the economics of local tourism.
AURA has had to proceed very carefully to search for ways in which lighting can be used to mutual benefit (see, e.g., Méndez and Boccas, 1999). This proved difficult at first, but efforts to set up a sister-city exchange between the county of Hawai'i and La Serena have allowed us to demonstrate that massive tourism and good lighting can coexist elsewhere and that we should be able to work together in Chile to achieve this. Economic arguments have so far been much more persausive than cultural and scientific arguments, although even these are now gaining force as the tourist potential of dark skies becomes better understood.
Coquimbo is currently engaged in construction of a US$6M "Cruz del Tercer Milenio" on a prominent hill overlooking the harbor. This is directly visible from AURA's observatory. The recent publication of the national lighting regulations has undoubtedly helped us in work with the municipality to design downward-looking light fixtures for this 80 meter-high religious structure.
Lighting engineers and others at the symposium with the qualifications and will to help have repeatedly expressed their frustration that professional astronomers have published so little information on the night sky background that engineers could use to check cause and effect in light pollution. AURA will again be taking the lead on the professional side in trying to contribute to an improvement in this situation.
Tololo and Pachón can be seen as a "canary in the mine" for modern astronomy in the southern hemisphere, just as astronomy itself acts in a similar way to provide early warning to the rest of mankind. Even a worst-case scenario with agressive population growth and no lighting control measures would predict an increase of ~0.m1 above the natural solar-minimum background over AURA's observatory (21.9V mag per square arcsec, 58 nanolamberts, at the zenith) by 2020 (Walker and Smith, 1999). Dave Crawford and the IDA have shown, in Tucson, what can be done to contain the effects of such population growth. A more realistic model shows that, even by 2030, light pollution at the zenith will still be only ~0.m08. This, however, does assume some success at light pollution control. We are working hard on such controls in Chile; the canary is not going to die readily.
The early efforts of the late Dr. Art Hoag in Tucson, Victor Blanco in Chile and the sustained efforts everywhere of Dave Crawford and the International Dark-Sky Association provided a vital foundation for this work. Sr. Edgardo Boeninger K. (then Minister/Secretary General to the Chilean President) explained to me in late 1993 the need to contact the Comision Nacional del Medio Ambiente (CONAMA), the newly-formed national environment agency.
Sr. Rodrigo Egaña the National Director of CONAMA has proved a staunch and constant supporter of light-pollution control (following a visit to Cerro Tololo at night). Sr. Pedro Sanhueza, the regional director of COREMA, took repeated risks in coming out publically at regional and national level in support of light pollution control. Sra. Cecilia Prats, regional director of SERNATUR, the Chilean national tourism agency was among the first to press effectively for marketing the dark skies in the region as a non-seasonal tourist attraction. Sr. Enrique Piraino provided technical assessment appropriate to the realities in Chile. The Cerro Tololo Light Pollution Control Committee was chaired for much of the last five years by Dr. Mark Phillips. He and his colleagues, Sres. Ricardo Schmidt, Mario Hamuy, Oscar Saá, M. Maxime Boccas and Dr. René Méndez (the current committee chair) must take most of the credit for what has been achieved from the astronomers' side in Chile.
This effort would have hardly started without the vision and persistence of the amateur astronomers and municipal authorities in Vicuña, Chile.