NASA AIM Spacecraft: Noctilucent Clouds Start Early this year - Video

Glowing electric-blue at the edge of space, noctilucent clouds have surprised researchers by appearing early this year. The unexpected apparition hints at a change in the "teleconnections" of Earth's atmosphere.

Every summer, something strange and wonderful happens high above the north pole. Ice crystals begin to cling to the smoky remains of meteors, forming electric-blue clouds with tendrils that ripple hypnotically against the sunset sky.

Noctilucent clouds (NLCs) are a delight for high-latitude sky watchers, and around the Arctic Circle their season of visibility is always eagerly anticipated.

News flash: This year, NLCs are getting an early start. NASA's AIM spacecraft, which is orbiting Earth on a mission to study noctilucent clouds, started seeing them on May 13th.

Cora Einterz Randall

"The 2013 season is remarkable because it started in the northern hemisphere a week earlier than any other season that AIM has observed," reports Cora Randall of the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado. "This is quite possibly earlier than ever before."

The early start is extra-puzzling because of the solar cycle. Researchers have long known that NLCs tend to peak during solar minimum and bottom-out during solar maximum-a fairly strong anti-correlation.

"If anything, we would have expected a later start this year because the solar cycle is near its maximum," Randall says. "So much for expectations."

For sky watchers, this means it's time to pay attention to the sunset sky, where NLCs are most often seen. An early start could herald brighter clouds and wider visibility than ever before.