A NASA satellite has captured the first occurrence of mysterious shiny polar clouds that form 50 miles (80 km) above Earth's surface. The AIM (Aeronomy of Ice in the Mesosphere) spacecraft returned some of the first data on these noctilucent or "night shining" clouds on June 11, 2007. In this image of the Arctic regions of Europe and North America, white and light blue represent noctilucent cloud structures. Black indicates areas where no data is available.

The clouds form in an upper layer of the Earth’s atmosphere called the mesosphere during the Northern Hemisphere’s summer season which began in mid-May and extends through the end of August and are being seen by AIM’s instruments more frequently as the season progresses. They are also seen in the high latitudes during the summer months in the Southern Hemisphere.

Very little is known about how these clouds form over the poles, why they are being seen more frequently and at lower latitudes than ever before, or why they have been growing brighter. AIM will observe two complete cloud seasons over both poles, documenting an entire life cycle of the shiny clouds for the first time.

AIM is providing scientists with information about how many of these clouds there are around the world and how different they are including the sizes and shapes of the tiny particles that make them up. Scientists believe that the shining clouds form at high latitudes early in the season and then move to lower latitudes as time progresses. The AIM science team is studying this new data to understand why these clouds form and vary, and if they may be related to global change.