Photos: Aurora Borealis from the Bay Area and far beyond

A powerful solar storm put on an amazing skyward light show across the globe overnight but has caused what appeared to be only minor disruptions to the electric power grid, communications and satellite positioning systems.

The U.S. National Oceanic and Atmospheric Administration said extreme geomagnetic storm conditions continued Saturday, and there were preliminary reports of power grid irregularities, degradation of high-frequency communications and global positioning systems.

But...