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Space Weather Alert - 24th April 2023

What Has Happened?

A video showing the CME observed on 21-Apr-2023.

Estimated 3-hourly K<sub>GBI</sub> indices (a measure of geomagnetic activity in the UK and Ireland) showing the storm intervals (green, yellow and orange bars) on 24-Apr-2023.


A full-halo Coronal Mass Ejection (CME) associated with a long-duration M-class solar flare and an adjacent filament eruption left the Sun at 17:44 UT on Friday 21st April 2023. The CME arrived yesterday evening at 17:35 UT (23rd April) causing major disturbance in the Earth’s magnetic field.

High levels of geomagnetic activity have been observed last night and this morning (between 23rd and 24th April). The ongoing CME effects are expected to cause further major STORM conditions during the next 24 hours, before slowly declining tomorrow.

Assuming clear, dark skies, there is a reasonable chance of seeing the aurora tonight. Those in Scotland, northern England and Northern Ireland have a better chance if the weather is favourable.


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The British Geological Survey is a geoscience research centre that is part of UK Research and Innovation (UKRI) and affiliated to the Natural Environment Research Council (NERC).

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.

Filament Eruption
An eruption of solar plasma (i.e. ions and electrons) associated with the upward movement of solar magnetic field lines into the corona. Filaments are usually dark against the bright solar disk but can appear bright (as 'erupting prominences') on the limbs of the Sun against the darkness of space. Filaments are often associated with CMEs

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