‘Erasing the sky’
CORDILLERA – When Dr. Robert Stencel spoke for the Vail Symposium’s Hot Topic Series last Thursday, it was more than just a lecture. He took the audience on a tour of the universe.Stencel, a professor of astronomy at the University of Denver and the director of DU observatories, came to the Summit Club to explain the toll artificial light is taking on the night sky.”The summer milky way is the grandest sight in the sky,” he said. “But in cities, the majority of kids have never seen it. What is the imagination cost we’re depriving these kids of? We’re erasing the sky.”To put the scope of the universe in perspective, Stencel began with a stop several light years away. On our closest neighbor, Mars, robots are exploring the surface. A satellite is orbiting Saturn. Last January, a probe was even launched to far-off Pluto.”Everyone is naturally interested in the rest of the wilderness,” Stencel said. “Maybe we’re onto something cosmic.”
Despite our curiosity for outer space, we’re collectively erasing the night sky from view, Stencel said. When urban kids look up, they can only see the moon and a handful of stars, not quite the image of Van Gogh’s Starry Night replicated on Stencel’s tie. Each year, $4 billion is spent in the U.S. to pump billions of watts through street lamps, headlights, sports fields, billboards, homes and businesses at night. As much as half of that light never makes it to the ground and escapes into space, Stencel said. That escaped light makes cities and towns – even Vail – visible from outer space, he said. This excess light causes glare that makes oncoming headlights appear blurry and also creates light trespass , which can keep you awake if it’s your neighbor’s light shining through your window, Stencel said. Together, these effects are known as skyglow.Stencel’s colleague, Dr. Aaron Reid, said the damage is not just in the sky. Skyglow disrupts the migration patterns of birds and sea turtles, which depend on moonlight to travel. Humans also suffer from the brightening night sky through sleep disorders, eye trouble and immune deficiencies, he said.Fortunately, the damage is reversible, he said.Reid plugged in examples of good and bad lights, urging the audience to use lampshades, lower wattage bulbs and timers or motion detectors to cut down on the amount of light that escapes into space unused. Good fixtures focus light downward where it’s needed, while bad lamps shoot light straight to the sky.
After the presentation, the lights were turned out and people lined up outside to peer through Stencel’s telescope.”Jupiter, the king of the planets, is reigning supreme tonight,” he said as he focused the scope on the largest planet and its four moons. The bright planet was visible to the southwest before the sun had completely set. Stencel swung his telescope around to let people get a closer look at a nebula, or gas cloud. The ring of light with a dark center is “like a celestial rose,” he said.
“It’s all connected,” Stencel said as he jumped from constellation Cygnus to the M13 star cluster. “It’s like reading a road map, it just takes some practice.”As he navigated guests around the night sky, he reminded them that it could all vanish if skyglow continues to creep across the Vail Valley. “Skyglow is very real for everyone,” he said. “Let’s get smart with light.”Brooke Bates can be reached at email@example.comVail, Colorado