GEOMAGNETIC STORM, SUBSIDING: Earth’s magnetic field is calming down on June 1st following nearly 15 hours of non-stop geomagnetic storming. The storminess was caused by the arrival of an interplanetary shock wave on May 31st (1618 UT). 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. More storms could be in the offing tonight as the solar wind continues to blow faster than 600 km/s. Aurora alerts: text, voice.

AURORAS IN THE USA: Last night, 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 (text, voice) 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. Aurora alerts: text, voice.