'Moderate' solar storm hitting Earth expected to bring aurora, possible disruption to power grids

Aurora is expected now Earth's been hit with a solar storm.
Aurora is expected now Earth's been hit with a solar storm. Photo credit: Getty Images

A solar storm that hit Earth earlier on Tuesday could disrupt power grids and also affect some satellites.

On Saturday, a sunspot hurled a flare, called a coronal mass ejection, towards Earth and it entered our magnetic field at about 3:30pm on Tuesday (New Zealand time).

Forecasters at the United States' Space Weather Prediction Center (SWPC) say the solar storm is 'G2' or moderate, which is the second level of its five-level storm scale. G1 storms are minor, while G5s are considered extreme.

Power systems closer to the north and south poles may experience voltage alarms and transformer damage if the storm lasts long enough, it adds.

Along with potential disruptions to technology-based infrastructure, it means an aurora australis, or aurora borealis for those in the northern hemisphere, could be seen while the storm hits.

New Zealand's geomagnetic activity jumped later on Tuesday afternoon, with the University of Otago's Aurora Alert reporting a level seven rating. This means an aurora was happening but since it was daytime it couldn't be seen. The rating has since dropped back to three, which means there's low activity.

The United States Geological Survey (USGS) says these magnetic storms can adversely affect technology because Earth's ionosphere, which reflects and modifies radio waves used for communication and navigation, is heated and distorted during them. This means long-range radio communication that relies on this reflection can be difficult or impossible and GPS systems can degrade.

"Ionospheric expansion can increase satellite drag and make their orbits difficult to control. During magnetic storms, satellite electronics can be damaged through the build-up and discharge of static electric charges. Astronauts and high-altitude pilots can be subjected to increased levels of radiation," the USGS says.

"Even though rapid magnetic field variations are generated by currents in space, very real effects can result down here on the Earth's surface. That includes voltage surges in power grids that cause blackouts."

Impacts from the geomagnetic storm are expected to disappear by Thursday, SWPC says.