a photo from the international space station shows the beauty of noctilucent clouds near the top of the earth’s atmosphere on july 13th 2012. these clouds have been a mystery dating back to the late 19th century, but now according to new data from NASA’s AIM spacecraft, it shows that “meteor smoke” or left over particles from when they burn up in our atmosphere is essential to the formation of these clouds.
www.science.nasa.gov/science-news/science-at-nasa/2012/07aug_meteorsmoke