A stream of high-speed solar wind is buffeting Earth's magnetic field. Last night, it produced a G1-class geomagnetic storm and a spray of pink auroras over Tromsø, Norway. "Oh yeah!" says Markus Varik, who photographed the display:
Auroras over Norway
© Markus Varik
"It's pure art to be around Tromsø these days with fantastic Solar Minimum pink auroras dancing above our moonlit snowy landscapes," he says.

Most auroras are green--the color of oxygen atoms being struck by energetic particles from space between 100 km and 300 km above Earth's surface. Pink appears when energetic particles descend lower than usual, striking nitrogen molecules at the 100 km level and below. Both colors were visible over Tromsø on Jan. 24th.

There is anecdotal evidence that Solar Minimum produces an unusual number of pink and even white auroras. Why? The chemical and magnetic composition of solar wind during Solar Minimum may differ slightly from other phases of the solar cycle, producing its own palette of color.

"Do we get one more day of Solar Storm conditions?" wonders Varik. The answer is "yes." Earth will remain inside the stream of solar wind for another ~24 hours. Currently it is blowing nearly 600 km/s, a value that favors Arctic auroras.