Aurora Section update
2015 November 18
It is recognised that the equinoxes can produce more auroral activity than other times of the year. This has been attributed to the tilt of the Sun’s axis relative to the Earth in March and September, making it more likely that the more open magnetic field lines from the Sun’s polar regions will carry plasma towards the Earth. This equinoctal activity is quite variable and certainly not totally predictable as some recent equinoxes have shown, but can be enhanced by coronal hole activity and a southerly direction of the Bz magnetic component.
Solar flares and resultant coronal mass ejections (CME) were for a long time thought to be the only way that the solar wind could be enhanced, but in the early 20th century, the concept of coronal holes was proposed. However, as these can only be seen in X-ray wavelengths, they were not confirmed until by instruments on Skylab in the 1970s. (continued…)
Ken Kennedy, Director, Aurora Section
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