Aurora Surprise. A Gift From An Interplanetary Shock Wave.

CHANCE OF STORMS: NOAA forecasters estimate a 50% chance of polar geomagnetic storms on June 2nd as a high-speed (700 km/s) solar wind stream buffets Earth's magnetic field. The warning comes on the heels of a lengthy G2-class geomagnetic storm on May 31-June 1 sparked by the arrival of an interplanetary shock wave. The source of the shock is unknown. Current speculation focuses on a corotating interaction region (CIR)--that is, a shock-like transition zone between high- and low-speed solar wind streams. Whatever it was, the impact ignited some beautiful auroras, described below.

AURORAS IN THE USA: On June 1st, Northern Lights spilled across the Canadian border into more than a dozen US states, turning the sky purple and green as far south as Colorado and Nebraska. Subscribers to the Space Weather Alert System knew the storm was coming, but others were surprised:

"Last night, I drove to Crater Lake National Park to photograph the Milky Way rising above the rim," reports Oregon photographer Brad Goldpaint. "I was staring upward towards a clear night sky when suddenly, without much warning, the aurora borealis began erupting in front of me." (continued below)

"With adrenaline pumping, I raced to the edge of the caldera, set up a time-lapse sequence, and watched northern lights dance until sunrise," he continues. "The moon rose around 2am and blanketed the surrounding landscape with a faint glow, adding depth and texture to the shot."

High-latitude sky watchers should remain alert for auroras tonight as Earth's magnetic field continues to reverberate from the impact. NOAA forecasters estimate a 40% chance of polar geomagnetic storms on June 1st. 

Solar wind
speed: 774.7 km/sec
density: 1.4 protons/cm³explanation | more dataUpdated: Today at 1746 UT

source: http://spaceweather.com/