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Light Pollution in Hawaii

by Richard Wainscoat

Honolulu city lights from Tantalus

Light pollution is particularly obvious if you view Honolulu from a high location, such as Tantalus.
Photo by Richard Wainscoat.

Next time you go out on a moonless, cloud-free night, take a moment to count the stars. Chances are, if you do this in central Honolulu, you'll be able to see 20 stars or less. If you do it in Hawaii Kai or Kailua, perhaps you'll be able to see 200 stars. Only if you live far from city lights, such as on the Big Island, will you be able to see the sky in its full glory, with 2,000 or more stars visible to the naked eye.

The reason why we see so few stars in Honolulu is that city lights have made the sky very bright. The brightening of the night sky by artificial sources is commonly called light pollution. Sadly, much of the light pollution across Hawaii (and most of Earth) is unnecessary, and is a result of poor lighting fixtures and poor lighting design.

Many of our streetlights are poorly designed, and direct some of their light directly up into space, where it is wasted. Athletic lighting is particularly wasteful, with almost half of the light spilling onto adjacent properties or lighting up the sky. Fully shielded light fixtures, which direct their light downward only, dramatically reduce light pollution and increase safety and visibility by reducing glare, which can be a particular problem for older people.

Use of fully shielded lights reduces energy costs, because all the light is directed where it is needed. California now uses only fully shielded lights on its highways. The city of Calgary in Canada has just replaced all of its streetlights with fully shielded fixtures that use lower wattage lamps, yielding $2 million per year in energy savings. Hawaii wastes more than $10 million per year in energy costs for poor lighting.

The night sky over the Big Island, where the Mauna Kea Observatories is located, is protected by a strong lighting ordinance, which has preserved the dark night sky over that island. The dark sky has now become a tourist attraction, with the Visitor Information Station on Mauna Kea attracting more than 100,000 visitors per year, many of whom participate in the evening stargazing program. Many of Hawaii's visitors have never seen a dark sky. Nevertheless, as the population of the Big Island grows, we must continue to be vigilant to protect Mauna Kea's dark sky, and work to update the Hawaii County lighting ordinance as necessary.

Maui County is now considering an ordinance to protect its night sky and the sky over Haleakala. In the next state legislative session, the Institute for Astronomy will again seek passage of legislation to improve lighting at the airports and harbors on the Big Island and Maui (where the lights are adversely affecting astronomy), and to improve the lighting on state highways.

Good lighting is important everywhere, not just near observatories. Everyone benefits from reduced road fatalities, better security, energy savings, the ability to see the sky at night, the increased ability of endangered birds and turtles to survive, and a better night's sleep.

Hear Richard Wainscoat speak online: (150 Mb)
The International Dark-Sky Association: