A ‘cannibal’ coronal mass ejection (CME) blasted out by the Sun could hit Earth today, triggering a powerful geomagnetic storm which may lead to radio blackouts.
Coronal mass ejections are caused when enormous loops of plasma erupting from the Sun’s surface ‘snap’ in half, releasing huge clouds of magnetised plasma into space.
When these collide with Earth they can cause disturbances in the magnetic field, causing radio blackouts in the most powerful cases.
‘Cannibal’ CMEs occur when two eruptions occur in quick succession, a smaller wave followed by a second, larger cloud, which engulfs the first. On Friday July 14 the first of today’s CMEs erupted from sunspot AR3370, followed by a second CME the following day from AR3363.
The phenomenon is rare, requiring two CMEs to be travelling along the same trajectory and at specific speeds.
As single CMEs neither of the current clouds would have been strong enough to impact the Earth’s magnetic field, but combined have formed a mass big enough to potentially trigger a G1 or G2 level disturbance, the most severe level of geomagnetic storm.
Alongside CMEs, solar flares also have the potential to cause communications blackouts. Solar flares are huge ejections of solar radiation that can reach the Earth minutes after an eruption – unlike days in the case of CMEs.
Earlier this month a powerful solar flare led to radio blackouts over parts of the US and Pacific Ocean. The radiation burst was caused by an X-class solar flare, the largest and most disruptive category. Today’s cannibal CME was caused by two C-class flares.
The Sun’s magnetic field goes through a roughly 11-year cycle. The current cycle, Cycle 25, is stronger than forecasters predicted, while the expected peak of 2025 may hit sooner.
In June 2023,163 sunspots were observed in June, twice as many as predicted and more than any other month in two decades. The increased activity has led to concerns of severe space weather events in the months and years to come.
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