The South African National Space Agency (Sansa) announced on Tuesday that moderate disturbances had been caused in the Earth’s magnetic field, creating moderate space communications disruptions, by a coronal mass ejection (CME) from the Sun. The CME occurred on October 9.
Most CMEs miss the Earth, but when they do hit our planet, they generate magnetic storms when they interact with the Earth’s magnetic field. These storms are graded on a scale developed by the US National Oceanic and Atmospheric Administration, from G1 (a minor storm) to G5 (an extreme storm).
The latest event created a G2 storm. This could result in disrupted communications with spacecraft, and necessitate the updating of satellite position calculations (because the storm would increase drag on the satellites). At latitudes above 55° (N or S), a G2 storm could affect high frequency radio communication with aircraft.
The Sun is continuously observed by Sansa’s Space Weather Centre (part of the Sansa Space Science directorate), which issues alerts when such activity could affect South African technology and operations. This latest storm and its effects were, consequently, monitored by the Space Weather Centre, which is based at Hermanus in the Western Cape.
Scientists measure disturbances in the magnetic field by what is called the K-Index. A K-Index of zero would mean no disturbances at all. K-indices less than four represent the ordinary fluctuations in the Earth’s magnetic field. The largest disturbance yet recorded at any location on the Earth had a K-Index of nine.
Globally, this latest storm achieved a K-Index of six, but above South Africa the Space Weather Centre noted a K-Index of only five. Thus, the storm had a lesser impact on South Africa than it did on other regions. And because South Africa lies at latitude 35° S, only minimal affects on the country’s radio communications and power systems could be expected.