The ongoing storm was triggered by a knot of south-pointing magnetism from the sun. During the early hours of Oct. 13th, the knot bumped into Earth's magnetic field, opening a crack in our planet's magnetosphere. Solar wind poured in to fuel the auroras.
More auroras are in the offing. NOAA forecasters estimate a 40% chance of strong polar geomagnetic storms on Oct. 14th when a solar wind stream is expected to blow past Earth. High-latitude sky watchers shuld be alert for auroras.