Coronal Mass Ejections (CMEs): Understanding the Solar Storms’ Power

A series of solar eruptions have been recorded in the previous years up to the present, concerning scientists as the emissions from the Sun could have a significant impact on Earth. Just recently, NASA predicted the occurrence of Minor G1-class geomagnetic storms on July 13 when a coronal mass ejection was expected to pass close to our planet. It has caused panic among many people as reports of an 'internet apocalypse' began circulating on social media platforms.

What are Coronal Mass Ejections?

Every so often, our Sun "burps" with energy as strong as 20 million nuclear bombs. This hiccup-like activity, known as coronal mass ejection (CME), is an explosive surge of superheated gas called plasma. It originates from the regions of the Sun's upper atmosphere or corona that are magnetically disturbed.

A CME includes particle radiation, such as protons and electrons, and powerful magnetic fields stronger than those normally in the solar wind. Each outburst also carries almost a billion tons of particles at a speed of hundreds of kilometers per second. The resulting blasts ripple through the Solar System and can cause interruptions in the activities of satellites and power grids on Earth.

The real cause of CMEs is not well understood, although astronomers agree that the Sun's magnetic field plays a significant role. Inside the Sun, the magnetic field is twisted into complex contortions by turbulence. When the area gets twisted too much, it gets curled and eventually snaps, releasing huge amounts of plasma into space.

CMEs often occur along with solar flares, although they can occur spontaneously. Within the 11-year solar cycle, the frequency of CMEs varies, from once a week at solar minimum to twice or thrice a day at near solar maximum.

Role of CMEs in Geomagnetic Storms

Since the particle emitted during CMEs are released by the Sun in all directions, most of them do not come near the Earth. However, there is still a possibility that an eruption will aim right at our planet. When this happens, a phenomenon known as geomagnetic storm occurs.

There is a region of space surrounding the Earth, known as the magnetosphere, created by our magnetic field and keeps us protected from the particles emitted by the Sun. During a geomagnetic storm, the Earth's magnetosphere suffers from a major disturbance due to a very efficient exchange of energy from the solar wind into the region of space that surrounds the Earth. CMEs are considered one of the most important drivers of geomagnetic storms since the largest storms that can occur are connected to them.

When the clouds of plasma hit our planet, the shock wave of plasma clouds compresses the Earth's dayside magnetic field and stretches out the nightside. The terrestrial magnetic field snaps back with the same energy as an elongated rubber band. This temporary restructuring of the Earth's magnetic field not only interferes with our technological activities but can also expose our planet to deadly cosmic rays.