Beware of ‘head-on’ northern lights, scientists warn

“Interplanetary shocks” that hit Earth’s magnetic field head-on are what scientists need to plan for to protect any electrically conductive infrastructure, according to a new study published today in Frontiers of Astronomy and Space Science.

The appearance of beautiful green, red, purple and blue aurora borealis, such as the global geomagnetic storm on May 10, can signal the arrival of strong currents on Earth that could damage power lines, oil and gas pipelines, railways and undersea cables.

Interplanetary shocks

An interplanetary shock, which can lead to the observation of magnificent northern and southern lights, is a disturbance of the solar wind. It is caused by coronal mass ejections from the sun. A CME is a cloud of magnetic fields and charged particles from the sun that pours into space at speeds of up to 3,000 kilometers per second.

This disturbance causes the compression of Earth’s protective magnetic bubble, which often triggers auroras. However, it is the impact angle of the interplanetary shocks that determines the strength of the currents, according to the researchers.

This is important because interplanetary collisions are much more common during solar maximum, which scientists believe is occurring now.

Magnetically induced currents can damage infrastructure that conducts electricity. The more powerful an interplanetary collision, the more powerful the currents and the more powerful the auroras. If scientists can predict that an impending interplanetary collision will be head-on, rather than a glancing blow, it will help protect infrastructure before impact, the researchers say.

Higher peaks

Researchers have found that shocks that hit the Earth head-on, rather than at an angle, cause the strongest geomagnetic currents. Using a database of interplanetary shocks and cross-referencing it with geomagnetic current measurements from a gas pipeline in Mäntsälä, Finland, in the “northern lights zone,” the scientists found that head-on shocks cause higher peaks in geomagnetic currents. This is because they compress the magnetic field more.

They also found that the most intense peaks occurred around “magnetic midnight,” the time of night (around actual midnight, local time) when the North Pole was between the Sun and Mäntsälä, on the night side of Earth.

Space Weather

“Aurorae and geomagnetically induced currents are caused by similar space weather factors,” said Dr. Denny Oliveira of NASA’s Goddard Space Flight Center, lead author of the study. Space weather is the flow of charged particles from the sun, the solar wind. “The aurora is a visual warning that electrical currents in space can generate these geomagnetically induced currents on the ground.”

On May 10, the northern lights were particularly intense. They appear as an oval around the polar regions, but on that date, the arrival of several CMEs caused the oval to expand. “The auroral region can expand considerably during strong geomagnetic storms,” Oliveira said. “Usually, its southernmost limit is around latitudes of 70 degrees, but during extreme events it can go down to 40 degrees or even more, which is certainly what happened during the May 2024 storm, the most violent storm in the last two decades.”

I wish you clear skies and wide eyes.

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