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Space Weather Alert - 8th September 2017

What Has Happened?

Image of the Sun showing the X9.3 flare. (Image: SDO/NASA)

Plot of the solar X-ray flux on the 6th September showing an increase due to the X9.3 x-ray flare.



On 6th September a X9.3 X-ray solar flare errupted from the Sun. This emerged from active region AR2673 which had earlier produced a M5.5 flare and associated coronal mass ejection (CME).

This is the most powerful X-ray flare of the current solar cycle and the strongest flare in a decade. It ranks within the top 15 flares in records stretching back to the 1970s.

Associated with this flare was a coronal mass ejection and radio bursts. These indicated that the assocated CME is fast moving and part of this CME is expected to arrive at Earth on the 8th September.

As the geomagnetic field is already disturbed we expect geomagnetic activity up to STORM G3 levels.

Assuming clear dark skies, and that the geomagnetic field is suitably disturbed, there is an increased chance of seeing the aurora. In the UK, those in Scotland, northern England and Northern Ireland may have the best opportunities, those further south may also see something.


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The British Geological Survey is one of the Natural Environment Research Council's Research Centres.

CME or Coronal Mass Ejection
The eruption of a portion of the outer atmosphere of the Sun into space, caused by rapid changes in its magnetic field. Often occurs along with a solar flare.

Coronal Hole
A region in the Sun’s outer atmosphere (corona) where hot material can flow unrestrained by its magnetic fields out into space.

Solar Flare
Energy released by the explosive reorganisation of magnetic fields within the Sun's atmosphere.

High Speed Stream
A fast moving stream of solar wind, responsible for magnetic storms.

Solar Wind
The ever-present expansion of the Sun’s hot outer atmosphere into the solar system, which carries space weather within it.

Sunspot/Active Region
A region of intense magnetic field in the Sun's visible outer atmosphere often associated with flares and CMEs.