Monday, May 11, 2015

Auroras Sighted, More to Come

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:

Shortly before Thomas took the picture, the interplanetary magnetic field (IMF) near Earth tipped south. This opened a crack in our planet's magnetosphere. Solar wind poured in to fuel the display.
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.


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