Bangalore: "When one says water pollution, it means that the water is full of pollutants. But, in the case of `light pollution', it is the darkness that is polluted by light," said B.S. Shylaja, scientist, Bangalore Association for Science Education, Jawaharlal Nehru Planetarium.

To see the night sky in all its glory, absolute darkness is essential, she said. "As the civilisation has improved, if we can call it that, we have become experts at keeping the darkness out. We have gone overboard and are throwing light into the atmosphere," she said.

Fallout

Dr. Shylaja said that "light pollution" has resulted in several problems. Human sight is slowly deteriorating. "We are slowly losing our capability to see in the dark," she said. The biological cycle of insects, nocturnal and otherwise, is also affected owing to light pollution.

Astronomers and astrophysicists around the world have now begun expressing concern about it, as they are worried about losing valuable information about the stars. The problem was first noticed during the 1980s, when the telescope atop Mt. Wilson in San Diego had to be shut down, as "light pollution" from the town was disturbing the vision area. "Money was being put in for research and scientists were not getting the results because of light pollution," she said.

In 1985, at the General Assembly of the International Astronomical Union in New Delhi, astronomers and astrophysicists from around the world began a signature campaign to save the telescope. The International Dark Sky Association filed a case in the courts in San Diego and fought to save the telescope. "The association won the case. The court directed the authorities concerned to take steps to reduce "light pollution". The telescope is functioning even now," she said.

Scientists use a method called stellar spectroscopy to study the chemical composition of stars. "Now that method cannot be relied upon, as when scientists apply it, they will only notice sodium or mercury lines. This is because of `light pollution'," Dr. Shylaja said.

Even Bangalore is facing the problem. "When we ask our amateur scientists to align their telescopes with the Pole Star, they find it difficult to do it. The only bright thing visible in the night sky now is the moon," she said.

Comet invisible

In 1997, the Hale-Bopp comet, which is bright, remained invisible in the city, she said. "Those in the villages could clearly identify it in the night sky. Even the meteor showers in 1999 could be visible clearly only in the villages," she said.

Dr. Shylaja said that there are ways to control "light pollution". "All vehicles could put a sticker and cover the top half of the headlights. Lighting of public buildings, such as the Vidhana Soudha, should be done from the top," she said.

Dr. Shylaja said that the authorities in San Diego made sure that only low-pressure sodium lamps were used. They also installed reflectors on all streetlights, by which all the light was directed towards the ground, instead of the sky. "These are minor things that can be incorporated effortlessly even in the city," she said.

Printer friendly page  
Send this article to Friends by E-Mail