A solar wind stream hit Earth's magnetic field during the early hours of April 30th, sparking a high-latitude geomagnetic storm (slowly subsiding). In the United States, auroras descended as far south as Marquette, Michigan, where Shawn Malone took this picture before sunrise:

US Auroras
© Shawn Malone
"High humidity and clouds dampened the light a bit, but the green liights were still bright enough to reflect off the waters of Lake Superior," says Malone.

High-latitude sky watchers should remain alert for auroras. The solar wind speed is high and gusty, and NOAA forecasters estimate a 40% chance of more geomagnetic activity during the next 24 hours.

More Images:
From Zoltan Kenwell of East of Edmonton Alberta, Canada; from Steve Milner of Ft St John, British Columbia, Canada; from Paul Klauninger of Ottawa, Ontario, Canada;