Aurora, Electrical Storm

 When I arrived at the Pawnee Buttes the moon was near the horizon but it was still bright enough to illuminate the landscape. The aurora was not visible to the naked eye. Only with a 30 second exposure did I know it was there. As I started to collect data, I noticed an electrical storm in the distance. The juxtaposition of the electrical storm and aurora made for a spectacular image.

A CME hit Earth's magnetic field on May 18th at around 0100 UT. Although it was just a glancing blow, the impact was enough to spark a G1-class geomagnetic storm. In the United States, Northern Lights descended as far south as Pawnee Buttes, Colorado.

"The aurora was not visible to the naked eye," says photographer Robert Arn. "Only with a 30 second exposure did I know it was there. As I started to collect data, I noticed an electrical storm in the distance. The juxtaposition of the electrical storm and aurora made for a spectacular image. (The moon near the horizon illuminated the landscape.)"

Elsewhere in the United States, faint auroras were sighted or photographed in, e.g., Washington, Vermont, and Iowa.