From the Regional Space Weather Warning Centre at the Space Science Directorate of the South African National Space Agency in Hermanus
A large sunspot, from region 1402 on the sun, which has a large latitudinal extent and is located in a geo-effective position, erupted in the early morning on Monday 23 January, at around 05:59 South African time.
The eruption produced a long-duration M9-class solar flare. The explosion's M9-ranking puts it on the threshold of being an X-class flare, the most powerful kind of solar flare. This is the first fast M-class flare of 2012. The flare triggered a proton event which is likely to have an impact on spacecraft in geosynchronous, polar and other orbits passing through Earth's ring current. In addition, strong geomagnetic storms are possible, and are likely to occur during the afternoon of Tuesday 24 January. Analysts at the Goddard Space Weather Lab say the CME should reach Earth on Jan. 24th at 16:18 South African Time (+/- 7 hr)
A halo CME was observed on 23 January by the coronagraphs on board the SOHO and STEREO satellites which monitor the disk of the sun in various spectral bands 24/7. A halo CME is a CME thrown in the direction of the Earth. The CME was a fast event (estimated speeds range from 1400 km/s to 2200 km/s). If it reaches the ACE satellite which is 1.5 million km from the Earth later today and maintains this velocity it will have an impact on the Earth's ionosphere and geomagnetic field about 18 minutes later and may interrupt radio communications. The ejected mass did not yet arrive at the ACE satellite. The interplanetary magnetic field is currently directed north, which may lessen the geomagnetic impact of the flare on the Earth.
At arrival, the magnetosphere might be disturbed. A geomagnetic storm can cause unwanted effects on satellites and their performances. A geomagnetic storm can alter also the features of the ionosphere, a layer which is crucial for signals transmitted to satellites or from an earth transmitter to an earth receiver, and can cause geomagnetically induced currents on power lines, which may cause stress on power distribution transformers.
