Periodically, the Sun ejects massive bursts of particles into the Solar System. Sometimes, when solar flares are aimed at Earth, the particles can create brilliant auroras in the night sky over many parts of the planet. Crashes can damage satellites, disrupt GPS signals and knock out power grids.
A space weather extreme storm watch was issued by a federal agency on Wednesday after a sun-gazing spacecraft observed a large solar flare emanating from a sunspot in the sun’s northern hemisphere, accompanied by a burst of particles known as a coronal mass ejection.
“The important thing here is that it was right in the center of the Sun,” Shawn Dahl, service coordinator for the Space Weather Prediction Center, part of the National Oceanic and Atmospheric Administration, said during a news conference Wednesday afternoon.
If the burst is right in the center of the Sun, at least part of it is aimed at Earth. It was large enough to cause potential disruption. The Northern and Southern Lights will be visible on Thursday evening and may come much closer to the equator than usual.
This is the second such watch, the space weather equivalent of the hurricane watch, released by the center in the last 19 years.
First, in May, America was alerted to a severe solar storm on its way to Earth. That solar storm reached “severe” status, but early warning allowed power utilities to prepare and help prevent major outages.
The latest event’s charged particles — protons, electrons and helium nuclei — are traveling at more than 2.5 million miles per hour and are expected to begin crashing into Earth’s magnetic field Thursday morning Eastern Time.
Mr. Dahl said the storm would not be as large as the one in May. “The difference is that we had a series of coronal mass ejections in May, one of which was faster than the other,” said Mr. Dahl said. “And it put everything together and improved the effect.”
But a geomagnetic storm lasts for about 36 hours. Auroras in the Northern Hemisphere could extend into the central United States if the storm reaches extremes. As far south as Alabama.
Predictions remain largely guesswork until waves of particles pass through NASA’s Advanced Composition Explorer, or ACE, and the Deep Space Climate Observatory, or DSCOVR, two spacecraft.
Both are about a million miles from Earth, providing 15 to 30 minutes of warning before solar storms reach Earth. At that point, the watch may be upgraded to alert.
In May, the center began talking to power grid operators about six hours before the storm hit.
This time, they arrived early because the power grid, already damaged by Hurricane Helen last month, will be further battered by Hurricane Milton in Florida.
“With all the hurricane relief work going on and the incoming hurricane moving into Florida and across the peninsula, we thought it would be prudent to contact them immediately,” said Mr. Dahl said. “We don’t know the actual situation there, but that’s our concern.”
Neither the May eruption, nor this week’s, were as intense as the Carrington event that struck Earth in 1859, disrupting telegraph stations, or the Carrington event that caused a nine-hour blackout in Quebec in 1989.
