Andrew Krueger / The Duluth News-Tribune via AP

The northern lights fill the sky over the south shore of Lake Superior east of Superior, Wis. above Duluth, Minn., pictured above, and are also seen in the sky over Lake Elora in northern Minnesota early, July 15, below. A solar storm sparked the show in the skies over the Upper Midwest and could also be active tonight.

See more PhotoBlog posts of the northern lights.

Brian Peterson / Minneapolis Star via Zuma Press

July 15, 2012 - Cotton, MN, USA - A spectacular display of northern lights filled the sky over Lake Elora in northern Minnesota early Sunday morning on July 15, 2012. A solar storm sparked the show in the skies over the Upper Midwest and could also be active tonight.