Skywatchers in Europe, Asia and North America were treated to perhaps one of the most widespread displays of the northern lights since the autumn solar storms of 2003.
Equally impressive shows of the aurora australis, or southern lights, were spotted in Australia and New Zealand.
The northern and southern lights, collectively known as the aurora, are most common in the high Arctic and Antarctic regions around the poles, but they can venture to the middle latitudes on rare occasions during potent geomagnetic storms.
The storms are caused by magnetic energy and electrons that are hurled into space by the sun.
The stronger the solar storm, the greater the effect — particularly if the resulting outburst is directed toward Earth.
Forecasters at the Space Weather Prediction Center in Boulder, Colo., issued warnings for a Level 4 out of 5 “severe” geomagnetic storm, which happens on average only 60 times every 11 years.
The episode may have been even more intense at times, sparking auroral displays as far south as California, Arizona, Arkansas and Virginia.
“Certainly what you saw last night was the biggest in the last five years,” said Bill Murtagh, program coordinator for the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center. “We’re going to see a lot more activity like this in the next several years because we’re going to be in the maximum phase of the sunspot cycle.”
NOAA warns that geomagnetic storms of this strength can cause “possible widespread voltage control problems” on power grids and can “mistakenly trip out key assets” on protective systems.
Satellites may see increased drag and, in some cases, even require minor corrective adjustments in positioning.
