Mystery Solar Storm Slammed Into Earth and Scientists Never Saw It Coming

A solar storm hit Earth on Saturday, sparking bright auroras over Canada and surprising scientists who monitor space weather.

On the evening of June 25, the National Oceanic and Atmospheric Administration's Space Weather Prediction Center (SWPC) issued an alert on its website stating that a G1-class geomagnetic storm was expected to occur through the night and into the following morning.

Geomagnetic storms are major disturbances of the Earth's magnetic field that occur when energy from the sun collides with our planet. These storms can create electric charges that interfere with the operation of power grids and also affect communication and navigation systems. It's the job of space weather experts to monitor the sun's activity to provide predictions as to when these storms might occur.

Although Saturday's G1 storm was the lowest class of solar storm—they can go up to G5—the SWPC said it could still cause weak power grid fluctuations, have a minor impact on satellite operations and even cause aurora to occur in northern parts of the United States like Michigan and Maine.

The sun
Space weather experts were shocked when a solar storm slammed into Earth with no warning on June 25, 2022. The above stock image shows an illustration of the sun in space. Solar eruptions can disrupt Earth's magnetic field. vitacopS/Getty

It's unclear if the shimmering lights did occur that far south, but one astrophotographer said they were surprised when they saw naked-eye auroras in Calgary, Alberta on Sunday. That afternoon, the storm stopped.

The reason behind the storm was not certain at first. Live Science reported that scientists initially suspected that a coronal mass ejection (CME) had caused the storm. CMEs are vast clouds of charged particles and magnetic fields that erupt from the sun regularly and are common culprits behind geomagnetic storms.

However, scientists eventually came to a different conclusion, that the storm was actually caused by a rarer and harder-to-detect phenomenon known as a co-rotating interaction region of the sun.

"At first [the storm] was a surprise; now the reason seems clear. A co-rotating interaction region (CIR) hit Earth's magnetic field, opening a crack in our planet's magnetosphere. Solar wind poured in to spark a rare solstice display of auroras," SpaceWeather.com reported.

A CIR refers to the transition between fast and slow streams of solar winds as they travel through space away from the sun. When the magnetic fields carried by these two streams meet, they can produce intense regions of magnetism that cause solar storms as CMEs do.

While CMEs can be spotted erupting from the sun days before they reach Earth to cause any effects, CIRs are harder to detect, Live Science reported. In fact, a CME was observed erupting from the sun on Sunday—but scientists weren't too sure which way it was facing when it did.

It's possible, but uncertain, that the CME could be traveling towards Earth. If this is the case, it might be a "near miss" and cause a mild geomagnetic storm on Thursday, according to SpaceWeather.com.