Geomagnetic storm watch: Did you see northern lights auroras this week? Here’s why

The National Oceanic and Atmospheric Administration (NOAA) issued a geomagnetic storm watch earlier this week for July 24, predicting possible visibility of the northern lights as far south as New York. 

This rare celestial event, driven by heightened solar activity, created a stunning light show for northern and upper Midwest residents. 

If you caught a glimpse of the auroras, you might be wondering what caused this spectacular display.

What caused the geomagnetic storm?

A coronal mass ejection (CME), released from the sun on July 21 came from a plume of plasma and magnetic field that carries electrically charged particles that can trigger geomagnetic storms when they collide with Earth's magnetosphere. 

RELATED: Could another 'Carrington Event' solar storm happen?

CMEs are massive bursts of solar wind and magnetic fields rising above the solar corona or being released into space, often traveling at speeds between 250 to over 3,000 kilometers per second.

What are geomagnetic storms?

Geomagnetic storms occur when CMEs interact with Earth's magnetic field. In the Northern Hemisphere, these storms can produce stunning auroras, known as the northern lights or aurora borealis. 

NOAA classifies geomagnetic storms on a G-scale, with G5 being the most severe. The current watch is for a G2-class storm, which is considered moderate.

How dangerous are solar storms?

Earlier this year, much of the U.S. was graced with a mesmerizing display of the northern lights courtesy of a potent solar storm. Observers as far south as Florida reported seeing the sky painted with vivid, swirling colors.

But not all geomagnetic storms are just a bunch of pretty lights. 

Solar storms, encompassing phenomena such as flares and CMEs, pose significant risks to Earth's technological infrastructure. 

"In an extreme case, when you have a very, very large magnetic storm, it can actually take out power and destroy transformers over a large region of the United States, for example. And it’s not localized like a tornado or a hurricane or flooding. It is regional - multiple states - like the whole New England area or the South or all of the West Coast, depending on how the power grid is oriented and where the energy is absorbed," NASA scientist Dr. Jim Spann has previously said.

The intensity of these storms can disrupt satellite operations, impacting GPS navigation, satellite television, and telecommunications. 

The most severe storms can even damage transformers in power grids, leading to widespread and prolonged electrical blackouts. Additionally, solar storms can increase radiation levels in space, presenting hazards to astronauts and potentially damaging the systems onboard spacecraft.

Have we experienced CMEs before?

Earth has been experiencing space storms throughout its history. Scientific data from ice samples taken from the Arctic show evidence of massive geomagnetic storms as early as 774 A.D. 

In 1859, the Carrington Event, named after British astronomer Richard Carrington, caused mass terror when it obliterated the global telegraph system. Auroras were visible as far south as Colombia in the most extensive recorded account of a solar storm to hit Earth. 

Telegraph operators reported receiving electric shocks when touching their instruments, as telegraph paper caught fire from the shortages. Experts say if a Carrington-style event were to occur today, the effects could be devastating, given our reliance on technology.

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