Japan's Star Watching Program Tracks Air and Light Pollution

Japan's Ministry of the Environment has been conducting an ongoing national program of star observations it calls the "Star Watching Network" twice a year, in summer and winter, since 1988. The aim of this program is to raise environmental awareness by tracking light and air pollution, through star observation. Participants apply through their prefectural governments, observe stars within a predetermined time frame of two weeks, and submit a report. In January and February 2003, a total of 3,843 people from 344 organizations in all 47 prefectures of Japan participated.

Participants observe stars by both the naked eye and binoculars. They are required to observe three parts of the Milky Way of different levels of the elevation with the naked eye, and to record the magnitude of the stars they can see with binocular in the Lyra constellation in a summer program and the Pleiades in winter. As factors such as altitude, city size and location of the observation sites affect visibility, the difference in the results at each site reveal the conditions of light and air pollution across the country.

According to the report compiled by the Ministry, the bigger the city, the less visible the stars become because of the effects of artificial lighting brightening the night sky. Starlight in cities is fading year by year, and in recent years this trend has been most noticeable in small cities with populations of 100,000 or less.

With the continuation of this Star Watching Program, the Ministry is promoting the use of proper outdoor lighting, such as minimizing the amount of light leaking to the sky and reducing brightness to the minimum level needed.


Posted: 2003/09/27 11:51:50 AM
Japanese version