By day, the Los Angeles area sky is known for its air pollution. At night, though, light pollution also takes a toll. Here, as in urban areas around the world, the glow of the cityscape overcomes all but the brightest stars in the sky. The artificial illumination interferes with astronomical observations, waylays animal migrations, and – some scientists suggest – could even affect human health. “A lot of children have grown up in the city and never really seen the dark sky at night,” said Connie Walker, a senior science education specialist at the National Optical Astronomy Observatory in Tucson. “It’s a terrible loss.” So, for the second year in a row, the observatory is leading an international effort to track Earth’s brightening skies, and anyone with eyes and an Internet connection can participate. The GLOBE at Night project will collect nighttime visibility data from March 8 to March 21 by tracking how many stars in the constellation Orion observers around the world can spot. The constellation is usually recognizable because of its closely spaced line of three bright stars, representing the belt of Orion the hunter. In the Los Angeles area, it will appear in the western sky. The project’s Web site, www.globe.gov/globeatnight, has features to show where in the heavens to search for the telltale stellar pattern. Observations should be collected about an hour after sunset. Participants can then compare their view of Orion against a range of possibilities that reflect increasing light pollution. In its inaugural year, the project collected 4,600 observations from all 50 states and 96 countries, Walker said. The results are then compiled into a map. As the project expands and adds new observations each year, Walker hopes to make the data available to scientists studying the impact of the electric glow. [email protected] (626) 578-6300, Ext. 4451160Want local news?Sign up for the Localist and stay informed Something went wrong. Please try again.subscribeCongratulations! You’re all set!