Taken on July 24th by NASA's AIM satellite, this is a satellite image of the North Pole - in fact, the whole Arctic region - complete with electric-blue noctilucent clouds. There must have been some great sightings from the ground.

Spaceweather.com explains what these clouds are:
Noctilucent clouds are, essentially, clouds of frosted meteor smoke. They form when wisps of summertime water vapor rise toward the top of Earth's atmosphere. Water molecules stick to the microscopic debris of disintegrated meteoroids, assembling themselves into tiny crystals of ice that glow beautifully in sunlight at the edge of space.