Source - NASA Science News for August 8, 2012
A key ingredient of Earth's strangest clouds does not come from Earth.
New data from NASA's AIM spacecraft shows that "meteor smoke" is
essential to the formation of noctilucent clouds.
The full story can be found here: http://science.nasa.gov/science-news/science-at-nasa/2012/07aug_meteorsmoke/
A companion video is posted below and can also be viewed at: http://www.youtube.com/watch?v=Qzs9ZOsjF-c