These clouds are doubly unusual. First, they are rare noctilucent clouds, meaning that they are visible at night — but only just before sunrise or just after sunset. Second, the source of these noctilucent clouds is actually known. In this rare case, the source of the sunlight-reflecting ice-crystals in the upper atmosphere can be traced back to the launch of a nearby SpaceX rocket about 30 minutes earlier. Known more formally as polar mesospheric clouds, the vertex of these icy wisps happens to converge just in front of a rising crescent Moon. The featured image — and accompanying video — were captured over Orlando, Florida, USA about a week ago. The bright spot to the right of the Moon is the planet Jupiter, while the dotted lights above the horizon on the right are from an airplane. [via NASA] https://ift.tt/M8edpCL