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The Webfooted Astronomer - January 2000


Minutes: Impromtu Light Pollution Discussion

by Leslie Irizarry

The December SAS meeting began with an informal discussion of observation of the Leonids. Randy Johnson got out of town and went to Manashtash Ridge. He used a snowplow shed as a windbreak. It was a great clear, cold night. He saw 200-300 meteors.

The telescope Makers meeting will held at 6:30 this Saturday. Peter Hirtle’s phone number is (206) 363-0897. All computer users are encouraged to subscribe to the Webftweb SAS mailing list: Books and calendars are here.

Light Pollution
On the spur of the moment, Woody Sullivan gave a slide presentation on light pollution. It is important to protect our dark skies. The slide show began by showing various sources of light around the world as seen by satellite. The biggest natural source of light is the Aurora Borealis. The Aurora is actually a ring centered on the geomagnetic pole. Some satellites are used for studying lightning. There are 30,000 flashes over the Earth in one year. The lightning is seen over land more than over the ocean.

A slide of the United States reveals that Puerto Rico is considerably more lighted than other islands, such as Cuba. A slide of Hawaii shows the light emitted by volcanism. Canada is considerably darker than the United States (except British Columbia). Grids and points of light represent roads and cities. A map of Europe illustrates how we live along coastlines: they are brighter than inland. Northern France is darker because of their national policy on light.

The Nile River Valley map demonstrates that if you live in Egypt, you live along the Nile. There is a lot of light at the Aswan Dam. The Sahara is dark. Lights in the southern rim of the Sahara are actually burning brush. This is an age-old practice to clear it for grass. In Sao Paulo and Rio de Janeiro, the lights seen there are fires in the Amazon. There is deforestation, colonization, and extraction of lumber. In Japan, there are lights in the Sea of Japan where there is fishing for squid and Solaray. They hang megawatts of light on their boats.

The International Dark Sky Association has a pair of slides: one showing the night sky of the Log Angeles Basin in 1908 vs. the present. The difference in the amount of stars seen is considerable. Responsible lighting includes full cut-off so that light will only go where it was intended. Mercury vapor lights have a lot of spectral lines spread out. Low-pressure sodium lights have primarily sodium-d lines in the yellow part of the spectrum. If you have to have light, use these. The Lick Observatory persuaded San Jose city fathers to use low-pressure sodium lights. In Flagstaff, most lights are low-sodium. There are some success stories. For example, New Mexico passed a resolution that the night skies are a heritage.

Hal Greene, a local attorney who loves skies, discussed his recent interactions with the Landmarks Preservation Board. The planned lighting at the Space Needle “got his goat”. The plan is for a light beam to be emitted into the sky from the Space Needle. Originally, a review of this scheme by the Landmarks Preservation Board had been planned. It was cancelled at the last minute: The Space Needle Corporation wrote that they are withdrawing because it considers itself “exempt” from any review or approval from the Landmarks Preservation Board. The reason for this is that the Landmarks Preservation Board does not have to review anything that is considered temporary. Hal believes that this is a loophole. The board appeared to be supportive and receptive to the input of those against the light at the Space Needle.

The light beam consists to 3 7000-watt Xenon lights mounted on top of the Space Needle. Each light has a 795 million-watt capacity. The Board has no control over the scope of the lighting. We need to get a columnist behind us. We also need to get photography and videography from different vantage points. (Several people volunteered to photograph the light over the New Years weekend.)

The opposition to this is that it can affect migratory birds, and it is a waste of energy. But primarily it is heading the wrong direction in terms of reducing light pollution. It is sending the wrong message. Hal Greene wants to appeal the claim that it is a categorically exempt electrical permit. Anyone, who is interested in participating in the protest of this issue, please give Randy Johnson or Karl Schroeder your name and phone number.

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