The Bureau of Meteorology has warned a severe geomagnetic storm event is expected to impact Earth from about 8pm AEST on Friday. 

Power outages may occur and satellite services could be impacted. 

The BOM has urged governments and critical infrastructure operators to take action to reduce potential impacts on infrastructure and essential services, such as power grids.  

Geomagnetic storms are not considered dangerous to human bodies.

Level G4 (severe) geomagnetic storm conditions are expected to arrive at Earth from about 8pm AEST on Friday before reducing to G3, with a chance of reaching level G4 again on Saturday. 

The G-scale is a measure of global geomagnetic activity, which refers to fluctuations in Earth’s magnetic field across the globe. The G-scale ranges from G1 (minor) to G5 (extreme).

The BOM predicts these geomagnetic conditions will likely continue until 6am on Monday AEST. 

If G4 geomagnetic conditions occur, bright auroras will be visible at unusually low latitudes, including dark-sky locations near Sydney and Perth.

“To view auroras, you ideally need a dark night with little cloud cover and an unobstructed view to the south,” the BOM posted on Facebook at 7pm AEST on Friday. 

“Bright auroras usually last for 1-3 hours and the best viewing time is around midnight — between 10pm and 2am.”

The intensity of geomagnetic storms in Australia is usually lower than the planetary average.

The BOM says this event is a result of four coronal mass ejections observed at 3:36pm AEST and 10:24 pm AEST on Wednesday, and at 8.24am AEST and 7.36pm AEST on Thursday.

Coronal mass ejections occur when large clouds of plasma and magnetic field erupt in the Sun’s outer atmosphere, according to the Australian Space Weather Alert System.

When the mass ejections hit Earth, they cause geomagnetic storms.

According to the BOM, geomagnetic storms of G4 level can potentially disrupt:

• critical infrastructure such as power grids, causing power outages
• satellite services, affecting communications and global position, navigation and timing services that use high-frequency radio communication.

The BOM will continue to monitor the situation.