City lights stand out in this composite NASA photo taken with the Suomi National Polar-orbiting Partnership satellite in 2012. NASA researchers combined hundreds of nighttime images in the green to near-infrared region of the spectrum, then mapped them over existing daytime images to create a realistic view of the planet on the side away from the sun.
Despite a handful of battles won—a few “dark sky preserve” sites designated here, some municipal lighting laws there—activists are still fighting the worldwide war against light pollution.
Just in time for International Dark Sky Week (5-11 April), the city council of Calgary, Alberta, Canada, approved tougher lighting standards for new developments. Two months ago, Canadian astronaut Chris Hadfield (@Cmdr_Hadfield) tweeted a nighttime image of Calgary from the International Space Station that showed the city’s illuminated street grid, visible even from Earth’s orbit.
The International Dark-Sky Association continues to certify remote locations on Earth that have low amounts of light pollution and offer good views of stars at night. Most recently, the group designated Brecon Beacons National Park in Wales as an “International Dark Sky Reserve” where the Milky Way is visible and authorities have taken steps to curb bright lights in the region. In the United States, Death Valley gained certification as a dark-sky park, and in Scotland, Galloway Forest Park expanded its dark-sky region.
Still, light pollution remains a problem for large swaths of our increasingly urbanized planet. The University of Hong Kong (China) found that its own city is the most light-polluted place on Earth, and the oldest astronomical observatory in China, Purple Mountain (Zijinshan) Observatory in the eastern province of Jiangsu, can no longer see the Milky Way and Polaris due to the encroaching light pollution from Nanjing.