Deep Sky Auroras
A solar wind stream hit Earth's magnetic field on May 18-19, sparking a G2-class geomagnetic storm. At the peak of the storm, Northern Lights crossed the Canadian Border into the USA. "The lights were faint, but beautiful," reports Donny Mott, who made a movie of the display over Spirit Lake, Idaho.
These are deep-sky auroras, barely visible to the human eye but an easy target for backyard cameras. "I used 13 second exposures at ISO 6400," says Mott. With those settings, his Sony A7s digital camera also picked up the Milky Way and the Andromeda galaxy. Geomagnetic activity is waning as Earth exits the solar wind stream. This means the only auroras for the next few nights will be of the faint, deep-sky variety. Photographers, crank up your exposure times.