If you can't see stars when you look up at night, the culprit may be light pollution. Although the phenomenon is less well-known and less threatening than air or water pollution, a growing number of activists worldwide are trying to keep the night sky clear by pushing for laws that would change how cities are lit. Stadium floodlights, ill-designed streetlamps and lighted advertising billboards are combining to produce a sky glow that makes it difficult for astronomers to work and for ordinary people to enjoy the beauty of a dark sky, says David Crawford, a retired astronomer and executive director of the International Dark-Sky Association in Arizona. Lights should be shining down where it's useful, not up, he says. It would be a crime if people couldn't see stars except in a planetarium. Night lights are also causing harm to animals, according to the Fatal Light Awareness Program in Toronto. The group is trying to prevent the deaths of perhaps 10,000 birds a year that become disoriented by lighted office towers in the Canadian city. The birds often circle the buildings until they crash into them or drop from exhaustion. One simple solution, says Crawford: turning off unused lights after dark. Illustration for TIME by Daryll Collins Panda Paradise?Confined animals have rarely had it as good as Jia Jia and An An, two panda bears from China's Sichuan province who relocated to Hong Kong last month. Their new home at the territory's Ocean Park is said to be one of the plushest anywhere: 2,000 sq m of natural trees, piped-in mists and artificial breezes, plus windows and a roof that open to allow natural air inside. Animal-rights groups are reserving judgment until they can view the facility, which opens to the public later this month. While the Animals Asia Foundation opposes the captivity of animals, Jill Robinson, founder of the Hong Kong-based group, would like to believe that the pandas' new home is as impressive as reports suggest. I hope [the site] encourages the betterment of facilities across Asia, she says. The architect, Tao Ho, who also designed Hong Kong's post-handover flag, points to his 14 cats as proof that he is an animal lover. I would like to see animals live in the wild, says Ho. But this is an interim facility. I tried to make it as natural as possible.