By Linda Copman
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| Photo: The view from the summit of Mauna Kea looking to the northwest. It is clear that the dominant sources of light pollution for Mauna Kea are located on the Big Island - Honolulu and Maui are relatively distant and make only a minor contribution to light pollution on Mauna Kea. Photo courtesy of Dr. Richard
Wainscoat, faculty member of the Institute for Astronomy
and member of the International Astronomical Union Working
Group on Light Pollution. |
Astronomers working in Hawai‘i have serious concerns regarding
light pollution. Increasing ambient light levels in the night
sky blurs the images that telescopes atop Mauna Kea are able
to capture.
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| Photo: A comparison of partially shielded
lights (left and extreme right) with a fully shielded
light (center right). Notice how little glare the shielded
light makes compared to the unshielded lights. This photograph
was taken on Bayfront Highway in Hilo. Photo courtesy
of Dr. Richard Wainscoat. |
The solution to the problem of light pollution is relatively
simple and readily available. Unshielded streetlights need
to be replaced with fully-shielded, low-pressure sodium lights – which
are the most energy efficient source of light currently available.
Low-pressure sodium lights are in widespread use on ‘Oahu and
in some countries in Europe. In many cases, low-pressure sodium
lights cost less to operate than traditional light fixtures.
Because these lights are monochromatic, their yellow-orange
light can be filtered out by astronomers using colored filters.
This is not possible for light from broad-spectrum lighting,
which contains light of many different colors.
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| Photo: Typical light pattern from unshielded or partially shielded lights. Note how much energy is wasted by sending it directly up into space. Image
courtesy of Dr. Richard Wainscoat. |
Many existing light fixtures on Hawai‘i Island are only partially
shielded and therefore contribute to the problem.
Unshielded light fixtures have several drawbacks:
- They waste light energy in the form of heat;
- They direct light up into the sky rather than down on
the ground;
- They are less efficient than shielded lights;
- They emit light pollution;
- They can compromise public safety by emitting poorly
directed light on roads and intersections – glare from
these lights decreases visibility;
- They detract from the visitor’s experience of dark skies;
- They cost more money to operate than fully shileded lights;
- They negatively impact endangered species;
- They negatively impact public health by making our neighborhoods
too bright to sleep; and
- They negatively impact astronomical observatories by
emitting unnecessary light pollution.
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| Photo: Typical light pattern from fully shielded lights. Note how light only goes downwards, where it is needed. Image courtesy
of Dr. Richard Wainscoat. |
The benefits of retrofitting existing light fixtures are incremental.
Each new “good” fixture helps alleviate the problem. The State
and County can work on this retrofitting project over a period
of time, as funds become available.
According to Dr. Richard Wainscoat, faculty member of the Institute
for Astronomy and member of the International Astronomical
Union Working Group on Light Pollution, some of the biggest
contributors to light pollution on Hawai‘i Island are the airports
and ports, which are State facilities. Astronomers are currently
working with State legislators to craft legislation that will
require State facilities to conform with County lighting codes
and to replace unshielded fixtures at State facilities with
shielded fixtures.
The biggest source of light pollution under the County’s jurisdiction
are streetlights. Streetlights in the Waikoloa and Waimea communities
have the greatest impact on the observatories, due to their
proximity to Mauna Kea. The astronomical community would like
the Counties, particularly Hawai‘i County, to develop a stronger
lighting ordinance -- which requires shielded street lights.
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| Photo: Glare from unshielded lights causes
light pollution. Photo courtesy of Dr. Richard Wainscoat. |
Ronald L. Laub, formerly the Facilities Manager at Keck Observatory,
is the Light Pollution Control Specialist at the Institute
for Astronomy. Laub reports that Island residents would welcome
darker skies around their homes. “Most residents that I’ve
talked to would prefer less light in their residential communities,” says
Laub. He has encouraged a few residents to express their concerns
about overly bright streetlights to the Hawai‘i County Department
of Public Works (DPW). The DPW responded by installing temporary
shields on the offensive streetlights, making a tremendous
improvement to the surrounding neighborhood.
Laub is currently working with the Hawai‘i County Council to
improve light pollution control measures. According to Laub,
the most effective ways to mitigate light pollution are to:
- Continue installing shielded fixtures on all replacement
and new street light fixtures;
- Raise funds to replace roughly 8,000 street light fixtures;
- Enforce the lighting ordinance now in place to include
both residences and businesses; and
- Review and update the lighting ordinance to correct weaknesses
in wording that make enforcement difficult.
Shielded lights direct the light where it is supposed to go,
on the streets and not up into the sky. They also require less
wattage per fixture, providing significant cost savings, which
is especially important in Hawai‘i – where we have the highest
energy costs in the country. Wainscoat suggests that the County
identify model communities in which to start replacing older
streetlights with shielded streetlights. As one community reclaims
its dark skies, this could eventually lead other communities
around the island to clamor for similar retrofits of their
streetlights.
Wainscoat points out that the city of Calgary, Alberta recently
retrofitted 40,000 streetlights at a cost of roughly $8 million,
or roughly $200 per light. The city of Calgary is realizing
$2 million per year in savings by retrofitting their streetlights – due
to reduced energy costs. Calgary should recoup their initial
investment in just four years. If Hawai’i County were able
to negotiate a similar price of $200 per light, we could conceivably
retrofit our 8,000 street lights for about $1.6 million.
Wainscoat and Laub recently met with Terry McGowan, a member
of the Board of Directors of the International Dark Sky Association,
to discuss some of the lighting challenges on the Island of
Hawai‘i. “He’s an expert on lighting and was very helpful with
his suggestions. He informed us of new lighting devices that
will certainly help in our efforts for this island,” reports
Laub. Laub is available to provide more information on this
subject; contact him at rlaub4@aol.com.
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| Photo: Ron Laub points out a good, shielded
light fixture installed outside W. M. Keck Observatory
headquarters in Waimea. “Dark skies are a must for astronomy,
tourism, the environment, and for future generations
to enjoy,” says Laub. Photo by Sarah Anderson. |
Enjoy
a podcast about Preserving Hawai‘i’s Magnificent Night
Skies featuring Dr. Richard Wainscoat.
The International Dark Sky
Association (IDA) offers numerous resources on this subject.
Check out their Dark Skies Finder at http://www.darksky.org/darksky.
See for yourself how effectively a shield over a bare light
bulb can improve the ground lighting and reduce wasted light.
Try this Paper
Plate Demo at home. 
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