One of the benefits of summer in the Northern Hemisphere is the appearance of noctilucent clouds, and despite all the heat we’ve had since mid-May, the summer solstice doesn’t kick in until 6:59 p.m. CDT today. SpaceWeather dot com says: "These glow-in-the-dark clouds are a 100+ year old mystery under investigation now by NASA’s AIM spacecraft. Originally confined to arctic latitudes, NLCs have spread in recent years with sightings in the United States as far south as Utah and Colorado." A gallery of photos is here. Wish they’d come to Texas. Maybe they will someday.
THE TEXAS SCRIBBLER 
Hmm… possible water exhaust from Space Shuttles.
Just wait for the conspiracy theorists to get wise to this. Oh boy…
Anyhow, very pretty.
Probably not the shuttle. It’s only been flying for twenty-seven years. The mystery’s been around for a lot longer.