Look -- up in the sky! It's a bird! It's a plane! It's a ...chemtrail? You've probably heard of these allegedly poisonous strips of stuff streaking across the sky, but what are they, exactly? Tune in to learn more.

Topics in this Podcast: poison, Weather, testing, Weapon, public, operation, Unsolved Mysteries, X-Files, theory, stdwytk, howstuffworks, United States, Science, conspiracy, matt, ben, history, Mystery, conspiracystuff, government, NASA, chemicals, war, experiment, Water, radiation