Visible from Space
This is scary:

Commander Eileen Collins said astronauts on shuttle Discovery had seen widespread environmental destruction on Earth and warned Thursday that greater care was needed to protect natural resources. . . ."Sometimes you can see how there is erosion, and you can see how there is deforestation. It's very widespread in some parts of the world," Collins said in a conversation from space with Japanese officials in Tokyo, including Prime Minister Junichiro Koizumi.

Collins, making her fourth shuttle flight, said the view from space made clear that Earth's atmosphere must be protected, too. "The atmosphere almost looks like an eggshell on an egg, it's so very thin," she said. "We know that we don't have much air, we need to protect what we have."