Trees: Unlikely Culprits in Ozone Pollution People aren't the only polluters — trees emit harmful compounds, too, as a recent map reveals. However, tree emissions would not be harmful were it not for the human emissions that react with these compounds, causing ozone pollution.
Landsat: 42 Years of Earth from Space Photos | Video NASA's first Landsat mission launched in July 1972. Seven more satellites have been launched since. Two of these, Landsat 7 & 8, are still active. The program acquired science imagery of natural disasters, urban change, water, ice, and farming.
Tonga May Have Been a Vast Seafaring Empire The seafaring empire of Tonga, an archipelago of about 160 Polynesian Islands in the South Pacific Ocean, once spanned more than a thousand miles, serving as the hub through which distant settlements exchanged artifacts and ideas, researchers say.
NASA's Chandra X-ray Observatory Celebrates 15th Anniversary Fifteen years ago, NASA's Chandra X-ray Observatory was launched into space aboard the Space Shuttle Columbia. Since its deployment on July 23, 1999, Chandra has helped revolutionize our understanding of the universe through its unrivaled X-ray vision.