Scientists say to watch out for ‘head-on’ aurora displays

Scientists predict that interplanetary shocks that directly impact Earth’s magnetic field could damage any infrastructure that conducts electricity, according to a new study published today in the journal Science. Frontiers in astronomy and space sciences.

The appearance of beautiful displays of green, red, purple and blue aurora, such as the global geomagnetic storm on May 10, can signal strong currents approaching Earth, potentially damaging power lines, oil and gas pipelines, railways and undersea cables.

Interplanetary shocks

An interplanetary shock, which can lead to observations of the beautiful 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 streams out into space at a speed of up to 1,900 miles (3,000 kilometers) per second.

The disruption causes Earth’s protective magnetic bubble to compress, often triggering auroras. However, it is the impact angle of interplanetary shocks that determines the strength of the currents, the study found.

That’s important because interplanetary shocks occur much more often during solar maximum, which scientists think is happening now.

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

Higher peaks

The paper found that shocks that hit the Earth head-on, rather than obliquely, produce the strongest geomagnetically induced currents. Using a database of interplanetary shocks and cross-referencing it with measurements of geomagnetically induced currents from a natural gas pipeline in Mäntsälä, Finland—in the “aurora zone”—the scientists found that head-on shocks produce higher peaks in geomagnetically induced currents. That’s because they compress the magnetic field more.

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

Space weather

“Auroras and geomagnetically induced currents are caused by similar space weather drivers,” said Dr. Denny Oliveira of NASA’s Goddard Space Flight Center, the lead author. 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.”

The May 10 aurora show was particularly intense. The aurora appears as an oval around the polar regions, but on that date the arrival of several CMEs caused the oval to expand. “The aurora region can expand enormously during severe geomagnetic storms,” ​​Oliveira said. “Normally the southernmost limit is around 70 degrees latitude, but during extreme events it can drop to 40 degrees or even further, which certainly happened during the May 2024 storm — the most severe storm in the past two decades.”

I wish you clear skies and big eyes.

Pick up my books Stargazing in 2024, A stargazing program for beginnersAnd When is the next solar eclipse?

Leave a Comment