Earth is entering a high-speed solar wind stream, and this is causing geomagnetic activity at high latitudes. First contact with the stream on May 22nd turned the sky over Cumbria, United Kingdom, deep purple:

Purple Skies
© Jon Cooper
Image Taken: May 23, 2012
Location: Shap, Cumbria, United Kingdom
"The sky was bright because of twilight, but we could still see these faint auroras," says photographer Jon Cooper.

So far the solar wind has not caused a full-fledged geomagnetic storm, but this could change during the next 24 hours. NOAA forecasters estimate a 15% to 20% chance of storms around the poles as the solar wind continues to blow.