Light
pollution from nearby cities (La Serena,
Coquimbo, Ovalle,
Andacollo, and Vicuña)
has been a concern over the last decade, due to the rapid
growth in population and development which this region of Chile has
undergone. AURA and CTIO have undertaken an agressive campaign - which
began in December 1993 - both
locally in the surrounding cities and at the Chilean congressional
level, to alert the Chilean public and governing agencies, in time, to
these
concerns (e.g., CTIO's web page in Spanish on light pollution at http://www.ctio.noao.edu/light_pollution/
and the web page in Spanish of the Oficina Para la Proteccion de los
Cielos del Norte de Chile, at http://www.opcc.cl/).
However, it is not the current level of lighting which is
worrisome. The concern over the last decade has been what changes the
future development of the
region will bring to what are presently very dark skies (which we of
course want to keep that way). A CTIO study by Alistair Walker and Hugo
Schwarz,
"Night Sky Brightness at Cerro Pachon", presents recent
numbers and several current projections, depending on population growth
and the
success of lighting controls. The study demonstrates that with
successful lighting awareness campaigns, such as that which CTIO/AURA
has launched, Cerro Pachon and Cerro Tololo can continue to be prime
astronomical sites far into the future. The Intendente of Chile's
4th Region (the maximum government authority
for the area in which Pachon and Tololo are located), at the
international, dedication
ceremony for SOAR in April 2004,
devoted his speech to communicating his recognition of the importance
of maintaining the dark skies over Pachon and Tololo (see page 3 of the
above link).
By May 2004, when we last took a census, 1/3 of
all the municipal street-lighting fixtures in the three
astronomically-sensitive regions of
Northern Chile had been changed to direct light
downwards. Evidence is clear in the towns and cities that the
program is continuing to gain momentum. Furthermore, post-curfew reductions in sky bightness have
now been detected low on the horizon from Cerro Tololo. This
remarkable, national-level enterprise
(involving a direct, capital investment of ~US$10M by generally
cash-strapped Chilean municipalities) is
expected to
be completed (including La Serena
and Coquimbo) by October, 2005, as
required by Chile's Presidential
Decree No. 686, the "Norma Luminica".
Using conservative population-growth models (only, so far), a reduction
of a factor of two in artificial night-sky brightness will extend the
current lifetime of any observatory by about two decades, as it will
take this long before the pre-changeover brightness level is again
reached. A pragmatic, more pessimistic estimate of 7%/annum growth in
artificial light pollution after the municipal lighting changeovers
would provide 10 years of breathing space if a factor of 2 reduction is
achieved as a result of the changeover, and 16 years if current levels
are reduced by a factor of 3. We expect that at least the
factor-of-two reduction
will have occured during the period 2004-2005 and we will continue to
monitor it
closely.
Environmental legislation in Chile is reviewed and updated every 5
years, by law. We will use the breathing space to work with the
authorities over the next two cycles (5yrs/cycle for Chilean
environmental legislation) to control
light pollution by
tightening the current legislation (following the successful leadership
given by Flagstaff and Tucson)
to include lighting zones with
lumen (or wattage) caps and so on - and so move on beyond the simple
first
step "Ilumine el Suelo, no el Cielo" (light the ground, not the
sky). This next step in the legislation can, for example,
emphasize more specifically and quantitatively the economic advantages
of measuring the light and comparing
against international lighting-engineering norms - i.e. using
the additional light that used to go up into the sky to light the
intended target and select the appropriate
power needed for each luminaire (light fixture). The appearance
of double-ballast lamps in Chile means that one can, for example,
reduce the power to the city's streetlights by 40% after lighting
curfew. Payback time on capital investment is then much
faster.
Achieving these savings will, however, of course not permit adding more
lights while maintaining the same excessive wattage in all the existing
ones! We are working closely with the International Dark Sky Association
(the current AURA-O Director is a member of the IDA Board of Directors)
in extending their new "Model Lighting Ordinance" (now available in
draft form from the IDA) to the realities
beyond the borders of the United States.
We are also working
closely with the environmental and education authorities in Chile as
part of a co-ordinated
effort to educate
the children in this region as
to the options thay have for controlling their environment in the
future. Finally, we are emphasizing the further economic
advantages of dark skies for "astro-tourism"
for the region. Of the
46,000 visitors to the Mamalluca
Municipal Observatory in 2003 - versus a total of 9,000 in 1999 -
14,000 came from outside
Chile in 2003. This number of foreign visitors is similar to the entire
population of the town;
all these visitors had to sleep and eat somewhere (at a time when local
tourism was still suffering from the collapse of the Argentinian
economy). Chile's President Lagos - a keen amateur astronomer - opened
the Collowara
public observatory in Andacollo in late June, 2004; he and the Minister
of Finance gave strong support for these concepts in their
speeches. We
have begun to work closely
with Euro-Chile and the local municipalities in this context to develop
and co-ordinate a "Ruta
Astronomica" in the
Elqui and Lamari
valleys (nearest Tololo and Pachon; p3 of the above link to the March
2003 NOAO Newsletter refers to
support by Intendente Felipe del Rio Goudie for protecting the skies
over Chile's IVth Region).
The priorities and timing of
these efforts have concentrated in the areas most likely to threaten
Pachon and Tololo in the decades to come - beginning with nearby Vicun~a
in 1993
and increasing the relative emphasis on La Serena and
Coquimbo once maps from
the First World Atlas
of the Artificial Night Sky Brightness became
available. Estimates for the evolution of the differential
contributions of the neighboring towns over the last decade and into
the future can be seen in the approximate models presented by Alistair
Walker and Hugo Schwarz. These models provide
further guidance to
our selection of priorities for future efforts and confirmation of
our
choices over the last decade; they will be refined when we have access
to a Second World
Atlas
of the Artificial Night Sky Brightness. We will need to remain
vigilant.