In the middle of the night a few weeks ago, electric-blue clouds appeared over Europe.  “They were glowing as if lit from within!” reports one observer.  The display marks the beginning of the 2005 noctilucent cloud season.  These beautiful clouds, which are something of a mystery, are usually spotted over high-northern latitudes.  In recent years, however, they’ve been spotted as far south as Colorado and Virginia.

You can read about the phenomenon here at SpaceWeather.com.  Better yet, take a look at the noctilucent cloud gallery for some awesome pics like the one below.