'Cannibal' CME from Sun to strike Earth: What is it
A "cannibal" coronal mass ejection (CME) formed as a result of several solar storms, including a "dark eruption" from the Sun, is on its way to strike Earth today. If that happens, the enormous CME could lead to a significant geomagnetic storm on our planet. What are these CMEs and what effects do they bring about? Let's find out.
Why does this story matter?
Of late, we are hearing more about solar eruptions and solar flares and there's a reason for it. The Sun is heading toward the peak of its current solar cycle, called the solar maximum. The giant star is known to get active during the time leading up to the peak phase and that's precisely what we are seeing now.
What are CMEs?
CMEs are large clouds of fast-moving magnetized plasma and solar radiation that are released into space from the outermost region of the Sun's atmosphere, called the corona. CMEs are often accompanied by another eruption, called solar flare. These are intense bursts of radiation that occur when the energy stored in 'twisted' magnetic fields, usually located above sunspots, are suddenly released, per European Space Agency.
What causes cannibal CMEs?
A cannibal CME occurs when a CME combines with a second faster-moving one. When the second CME catches up with the initial one, it creates a single large cloud of plasma.
CMEs cause geomagnetic storms on Earth
If CMEs make their way to Earth, they can cause geomagnetic storms, which are major disturbances in our planet's magnetic field. These storms can lead to radio blackouts on the planet. Conversely, they can also have a positive effect. Geomagnetic storms can produce stunning aurora displays but they happen much farther away from Earth's magnetic poles than they usually occur.
How the cannibal CME set to strike Earth today emerged?
The cannibal CME set to strike Earth today started when a CME erupted from a sunspot, called AR3370 on July 14. Sunspots are planet-sized regions on the Sun associated with strong magnetic fields. This CME was accompanied by what's called a dark eruption. It is a solar flare that contains cool plasma, making it look darker compared to the rest of the Sun's surface.
The second CME formed from a much larger sunspot
On July 15, a second and much faster CME emerged from a larger sunspot called AR3363. A simulation from the National Oceanic and Atmospheric Administration reveals that the second CME will catch up with the first CME and merge to form a single cannibal CME. This strong wave is on course to strike us today but no harm is expected.
Both CMEs belong to C-class solar flares
Solar flares fall into five classes in increasing intensity: A, B, C, M, and X. Both CMEs, released on July 14 and 15, belong to C-class solar flares. Individually, these CMEs are not strong enough to cause a major geomagnetic storm. However, when combined, the cannibal CMEs can lead to G1 or G2 level disturbance, the two highest classes of geomagnetic storms.
What makes cannibal CMEs rare
Cannibal CMEs are fairly rare, the reason being they require consecutive CMEs that match in both alignment and speed. We have seen a few cannibal CMEs in the past years. In November 2021, a cannibal CME struck Earth, causing one of the first major geomagnetic storms of the current 25th solar cycle. Two more CMEs hit Earth in March and August of 2022, respectively.
The Sun is expected to reach solar maximum in 2024
Cannibal CMEs are known to happen more frequently as the Sun heads toward solar maximum. During this peak time of activity, the Sun's magnetic field gets unstable, causing more sunspots and solar flares. The sunspots reached their highest number in 21 years this June. According to recent predictions, the solar maximum is expected to occur in mid to late 2024.
