ELECTRIC-BLUE CLOUDS:

The 2011 noctilucent cloud (NLC) season has begun. For the past few nights, observers in northern parts of Europe have spotted velvety, electric-blue tendrils rippling across the sunset sky. NLCs are a summertime phenomenon first reported by polar observers in the 19th century.  In recent decades, for reasons no one fully understands, the clouds have intensified and spread  as far south as Utah and Colorado.  Visit today's edition of http://spaceweather.com for photos and observing tips.