The northern lights have been vivid over the Philly region Thursday night

Undulating, rose-colored and purple-ish northern lights became visible over parts of the Philadelphia region on Thursday night, for the first time in over 20 years.

Especially in areas away from the city lights, the sky show was apparent in the early evening as far south as southern Delaware in areas where the sky was reasonably dark, the result of a solar storm whose effects were expected to continue into Friday. And even in parts of the city.

» READ MORE: The northern lights put on a show over Philly Thursday night. Here’s what people saw.

Scientists at the Space Weather Prediction Center Thursday afternoon had issued a warning for a “severe” geomagnetic storm — with an outside chance that it would reach the “extreme” level. The storm, which arrived at 11:15 a.m. Philadelphia time, quickly intensified and could affect power grids and electrify the night sky with undulating curtains of lights this far south.

If circumstances aligned, it’s possible the northern lights would be visible as far south as Alabama, the center said.

Right after nightfall they became evident in some areas around the city, and vividly in the dark skies above the Pine Barrens.

in an update issued at 5 p.m., the Space Center reported that the storm had reached a magnitude that would have made the lights visible around or just to the north of the Philly region. However, another light in the west — the sun — made that development moot.

The center’s scientists said that the storm, which was ejected from the sun about 10 p.m. Tuesday, reached Earth while traveling at 1.5 million mph. The storm was expected to continue into the overnight hours, with fluctuating intensity, they said.

But this was not a supermarket panic-run situation. The center said it also was unclear what effects the storm would have, although it could have some impacts on the nation’s power networks and telecommunications.

Given the continuing recovery from Hurricane Helene, and the threat of cataclysmic damage from Hurricane Milton, space weather officials had issued a watch Wednesday because they wanted to give FEMA and others as much of a heads-up as possible.

“We don’t know yet what this storm will bring us,” said Shawn Dahl, the center’s service coordinator.

The potential of seeing the northern lights around Philadelphia was in play, said space center project manager Bryan Brasher. And while a certain skepticism based on recent experiences would have been understandable, this time it actually happened.

As was the case last week, a potent solar storm — commonly called a sunspot — ejected massive quantities of charged particles and magnetic fields that have been streaming toward Earth. Under certain circumstances, the solar material from the so-called coronal mass ejection interacts with the Earth’s magnetosphere to turn on the aurora borealis.

This storm, the scientists said, appears to be stronger than its predecessor. It is a G4, or “major” geomagnetic scale, and possibly the a G5, which is at the top of the scale.

A G4 storm in May resulted in the lights being visible all the way to Florida.

Solar storms have been erupting more frequently lately because the sun has been approaching — or possibly has reached — the peak of an 11-year sunspot cycle that began in 2019.

“The sun has been quite active,” said Brasher, more active than had been forecast. The center scientists also said it’s possible that the peak won’t occur until early next year and that heightened sunspot activity could lap into 2026.

Center scientists said it was unclear if the coming storm would have any effect on hurricane-recovery efforts by interfering with the power grid or communications system. Center scientist Rob Steenburgh said that Florida’s low latitude would argue against that happening.

Brasher, however, said that NOAA thought it “prudent” to raise cautionary flags.

The aurora can appear without notice, vanish quickly, then reappear.

Brasher recommends signing up for alerts from the space weather center.

The center also posts three-day outlooks for solar storms and a corresponding index that’s an indicator of storm intensity and a handy number for tracking aurora potential, along with a chart for monitoring the behavior of the index in three-hour intervals.

Should that index reach 8, Philly could be in play.

You can follow the space weather center on X or Facebook, and the Aurora Dashboard offers real-time predictions.

And it’s a safe bet if the northern lights show up anywhere around here, social media will light up also.