Honolulu city lights jeopardize starry nights
A UH astronomer says downtown residents can see only 20 stars
If you look up at the sky on a clear night and have trouble seeing stars, it is probably because of too much light, says University of Hawaii astronomer Richard Wainscoat.
He will discuss "The Disappearing Universe -- How Light Pollution Is Ruining Our View of the Night Sky" tomorrow at 7 p.m. in a free public lecture at the Institute for Astronomy, 2680 Woodlawn Drive.
"The fundamental problem is the widespread use of poor-quality light fixtures to send light directly up in the atmosphere," Wainscoat said. "The light then gets scattered back to us and makes the sky bright at night.
"We're losing our ability to see the night sky, especially people who live in Honolulu." The light also is impinging upon the Mauna Kea and Haleakala observatories, he said.
Wainscoat estimates residents in urban Honolulu can see only about 20 stars a night. In Kailua, where he lives, residents can see about 200 stars, he said.
"In a rural area, away from city lights or on an outer island like the Big Island where the sky is protected by a lighting ordinance, you can see 2,000 stars on a dark night."
Wainscoat offers this method of figuring out how many stars you can see in your area: Make a shaka at arm's length, about 20 degrees. Count how many stars you can see in the square between the thumb and little finger, and multiply by 50 to get the total stars in the sky above the horizon.
The light pollution is difficult to notice because it has grown slowly, "mostly because government agencies are buying poor-quality light fixtures," Wainscoat said.
He said he has been trying to persuade authorities to use shielded light fixtures that only shine light downward.
"This is going to be ever more important as energy costs increase," he said. "The cost of electricity for street lights is going to increase. We need to use energy wisely to send light downwards and not upwards into the sky.
"A lot of this is basic stuff, but it is not happening."
Light being used for advertising also is a problem, he said. "A gas station will make itself very bright to draw customers, and one across the road will make itself even brighter."
Many visitors come from places with more light pollution, "and they are astonished on the Big Island how beautiful the night sky is," Wainscoat said.
"The dark sky has a lot of value in terms of tourism. It is something we should try to preserve."