What is a geomagnetic storm? Why you saw the northern lights

Americans from Arizona to Delaware got a look at the northern lights on Oct. 10 as a result of a geomagnetic storm impacting the Earth. A second view could be in play tonight , too.

The storm is a result of a coronal mass ejection, CME, that sped toward Earth at 2.5 million mph. A coronal mass ejection is a large expulsion of plasma and magnetic field from the sun’s corona, according to NOAA's Space Weather Prediction Center.

The geometric storm has diminished some since Thursday night, according to the SWPC. But associate professor of physics and astronomy at University of Delaware Bennett Maruca said seeing the northern lights again tonight is "quite possible."

What is a geomagnetic storm and what causes it?

University of Delaware professor Bennett Maruca said solar wind is always sending particles into deep space, and when they interact with Earth's atmosphere, they move towards the poles. This recent solar flare and CME was an "extra blast" of charged particles of ionized gas that was "dumped" into the Earth's magnetic fields, causing the storm.

Because of the storm, the auroral region expands further than polar regions into lower latitudes, including the continental United States.

"You just have a lot more energy being driven into Earth's magnetic field in the atmosphere," Maruca said.

How often does a geomagnetic storm happen? Will the northern lights return?

Solar activity comes in cycles of 10-12 years. It goes from solar minimum, with few sunspots, flares and CMEs, to solar maximum, where activity increases dramatically. Maruca said the sun is headed towards a solar maximum in the current cycle, meaning there could be more geomagnetic storms in the coming months.

This is the second time this year the northern lights have extended to the Northeast. A major geomagnetic storm occurred in May 2024, bringing the aurora to most of the country. Unfortunately, many in the region experienced cloudy nights.

How can I see the northern lights tonight?

When seeking out the incredible phenomena, Maruca said to find the darkest possible place. He also said to use a cellphone camera for better color contrasts and a clearer view.

"When I used my phone, just with the automatic settings doing the long exposure, and then it bumped up the contrast, I took an image, and then I look, I was like, 'Oh my god, there it is,' and I was able to see both the red and the green," he said.

Despite studying physics and astronomy, Maruca has never actually seen the northern lights before last night. He said it was similar to how students react when they see planets through a telescope in their real form.

"I kind of had that moment last night," he said. "It was like, 'Oh, wow. It really looks like that.'"

This article originally appeared on NorthJersey.com: What is a geomagnetic storm? Why you saw the northern lights