Space weather can be fierce.
Watching the Northern Lights might feel like an electrifying experience, but they can quite literally lead to shocks on Earth.
These spectacular auroras are caused by ‘head-on’ blows to Earth’s magnetic field, which can also damage critical equipment such as power lines, oil pipelines, railways and undersea cables, scientists have warned.
Solar storms are well known to cause communications blackouts due to their effect on the atmosphere, but interplanetary shocks that strike Earth’s magnetic field also cause powerful ground-level electric currents – threatening key infrastructure.
Auroras have inspired myths for thousands of years – but only now, with modern technology dependent on electricity, is their true power being appreciated.
The new study, published in the journal Frontiers in Astronomy and Space Sciences, shows that the same forces that cause auroras also cause currents that can damage infrastructure which conducts electricity, such as pipelines.
Researchers showed that the angle at which interplanetary shocks strike is key to the currents’ strength, offering an opportunity to forecast dangerous shocks and shield critical infrastructure.
Lead author Dr Denny Oliveira, of Nasa’s Goddard Space Flight Centre, Maryland, said: ‘Auroras and geomagnetically induced currents are caused by similar space weather drivers.
‘The aurora is a visual warning which indicates that electric currents in space can generate these geomagnetically induced currents on the ground.
‘The auroral region can greatly expand during severe geomagnetic storms.
‘Usually, its southernmost boundary is around latitudes of 70 degrees [in the Arctic and Antarctic], but during extreme events it can go down to 40 degrees [including Europe] or even further, which certainly occurred during the May 2024 storm – the most severe storm in the past two decades.’
He explained that auroras are caused by two processes: either particles ejected from the Sun reach Earth’s magnetic field and cause a geomagnetic storm, or interplanetary shocks compress Earth’s magnetic field.
Dr Oliveira said those shocks also generate geomagnetically induced currents, which can damage infrastructure that conducts electricity.
However, there was no mention of threats to humans during the shocks.
He warned that more powerful interplanetary shocks mean more powerful currents and auroras – but frequent, less powerful shocks could also do damage.
‘Arguably, the most intense deleterious effects on power infrastructure occurred in March 1989 following a severe geomagnetic storm,’ he said.
‘The Hydro-Quebec system in Canada was shut down for nearly nine hours, leaving millions of people with no electricity.
‘But weaker, more frequent events such as interplanetary shocks can pose threats to ground conductors over time.
‘Our work shows that considerable geoelectric currents occur quite frequently after shocks, and they deserve attention.’
The team also suggests that shocks which hit the Earth head-on, rather than at an angle, induce stronger geomagnetically induced currents, because they compress the magnetic field more.
To investigate, they cross-referenced interplanetary shocks with readings of geomagnetically induced currents from a natural gas pipeline in Mäntsälä, Finland, which is generally in the auroral region during active times.
To calculate the properties of the shocks, such as angle and speed, they used interplanetary magnetic field and solar wind data.
The shocks were divided into three groups: highly inclined shocks, moderately inclined shocks, and nearly frontal shocks.
The researchers found that more frontal shocks cause higher peaks in geomagnetically induced currents both immediately after the shock and during the following sub-storm.
However, because the angles of the shocks can be predicted up to two hours before impact, the research team say the information could allow protections to be set in place for electricity grids and other vulnerable infrastructure before the strongest and most head-on shocks strike.
Dr Oliveira said: ‘One thing power infrastructure operators could do to safeguard their equipment is to manage a few specific electric circuits when a shock alert is issued.
‘This would prevent geomagnetically induced currents reducing the lifetime of the equipment.’
