http://www.space.com/scienceastronomy/p ... 00222.html
[quote="""]Striking and polar mesospheric clouds, also known as noctilucent clouds, were photographed recently by space station astronauts as the crew soared over the bottom of the planet.
While the clouds can be seen frequently from the International Space Station, they are seen only be a few people on Earth because they form over the high latitudes of both the Northern and Southern Hemispheres during their respective summer months.[/quote]