Winter 2006 W. M. Keck Observatory 


 In this Issue:
 The Dawn of the Universe
 A New Wave of Innovation
 Opening Doors to Dream
 Hawaiian Punch


By Linda Copman

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.

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.

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.

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.

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.

Photo: No ‘olua by Diane Repp.
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.

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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