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Space Weather Alert - 11 September 2015

What Has Happened?


A chart showing current estimated global geomagnetic activity (Kp)

Solar wind data from the ACE spacecraft (NASA).

This morning, due to the influence of a high-speed solar wind stream from a large coronal hole, geomagnetic storm conditions were observed when the interplanetary magnetic field (IMF) within the solar wind slipped strongly southwards.

While the IMF has since retreated northwards, further geomagnetic storms and resulting auroral displays are possible, particularly if the IMF turns southward again. The coronal hole high-speed stream is likely to affect the Earth's magnetic field for the next 24-48 hours.

The effects of a second coronal hole are expected to make themselves known by 13 September. This is a bit further north on the solar disc than the one currently bathing the Earth, but could still cause appreciable disturbance, especially when the heightened activity levels of the past week are taken into account.

Keep an eye on current geomagnetic conditions using the links below and if things start to kick off again and the sky is clear where you are (particularly at high latitudes), maybe go outside and have a look to the North.



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

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

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

The variation, minute by minute, of the strength and direction of the Earth’s magnetic field. Measured in units of nano-Tesla (for the strength of the field) or in degrees (direction of the field).

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