Auroras Sighted, More to Come
Mother's Day in Canada began with a sunrise display of Northern Lights. On Sunday, May 10th, Harlan Thomas photographed a green band above the rosy twilight east of Calgary:
More auroras are in the offing. NOAA forecasters estimate a 45% chance of polar geomagnetic storms on May 11th when a co-rotating interaction region (CIR) is expected to hit Earth's magnetic field. CIRs are transition zones between fast- and slow-moving solar wind streams. Solar wind plasma piles up in these regions, producing density gradients and shock waves that do a good job of sparking auroras.