A violent sunspot eruption on the surface of the Sun has kicked up a solar flare, caused a coronal mass ejection (CME) to fling itself towards Earth and started the strongest solar radiation storm since September 2005. [Updated: See below]

On 23 January, the sunspot 1402 popped. This produced an M8.7-class solar flare — an intense burst of radiation coming from the sunspot’s explosive release of magnetic energy. That’s perilously on the threshold of being an X-flare: the most powerful kind of solar burst.

The flare caused a coronal mass ejection. That’s when the the corona (the outer solar atmosphere) closes its strong magnetic field over sunspot groups. The confined solar atmosphere inside can bubble up and violently release great, fast balls of gas.

The Solar and Heliospheric Observatory (SOHO) and Nasa’s Stereo-B spacecraft detected the CME, which is rushing towards Earth at 2200 kilometres a second. The leading edge of the gaseous bubble will reach Earth on 24 January at 14:18 UTC, and deliver a strong glancing blow to Earth’s magnetic field on 24 or 25 January as it sails past our planet.

 

For any Martians reading, the mass ejection will hit the Red Planet during the late hours of 25 January.

CMEs are very common — during the active peak of the Sun’s cycle more than one can be expelled every day. When they hit Earth they can have an adverse effect on our satellites. “Spacecraft in geosynchronous, polar and other orbits passing through Earth’s ring current and auroral regions could be affected by the cloud’s arrival,” says Spaceweather.com.

The Space Weather Prediction Center forecast is for Moderate (G2) level geomagnetic storming over the coming days. This means “high-latitude power systems may experience voltage alarms and long-duration storms may cause transformer damage.” Possible changes in drag could affect the orbit of spacecraft. In addition, strong geomagnetic storms are possible. High-latitude sky watchers should be on alert for awesome auroras.

The solar radiation storm is a little less common. This burst of fast moving, highly energetic protons is known as a “solar energetic particle” event, and has caused the strongest solar radiation storm since September 2005, according to Noaa’s Space Weather Prediction Center. This rush of radiation, in the form of solar protons, already has begun bombarding the Earth and will continue through Wednesday.

Noaa has ranked the storm as S3. This represents a radiation hazard, so astronauts lined up for spacewalks are recommended to stay inside, and planes might need to be rerouted for the safety of passengers and crew in aircraft at high latitudes.

For satellites, “single-event upsets, noise in imaging systems, and slight reduction of efficiency in solar panels are likely”. Spaceweather warns that it could also “cause isolated reboots of computers onboard Earth-orbiting satellites and interfere with polar radio communications.”

Updated 17:20 24/01/2011: The coronal mass ejection has now hit Earth, and the NOAA NWS Space Weather Prediction Center has revealed that the radiation storm’s ferocity has increased. With the 10 MeV protons reading spiking to 6300 proton flux units, that makes this storm “the largest Solar Radiation Storm since October 2003.” Don’t worry, though: it’s still being ranked at S3 severity.