What are Coronal mass ejections (CMEs)?

Coronal mass ejections (CMEs) are giant eruptions of hot plasma and magnetic fields from the Sun’s corona, the outermost layer of its atmosphere. These eruptions can contain billions of tons of material traveling at millions of kilometers per hour.

What causes CMEs:

• Magnetic Reconnection: The main culprit is a process called magnetic reconnection. The Sun’s corona has twisted, tangled magnetic field lines. When these lines reconnect, they snap and release tremendous energy. This often happens in active regions with sunspots.
• Filament Eruption: Another cause is the eruption of prominences or filaments. These are cooler, denser clouds of plasma suspended in the Sun’s corona by magnetic fields. When the magnetic configuration holding them up gets disturbed, they can erupt outwards as a CME.

CMEs are interesting because:

• Solar Storms: They are often associated with solar flares, but not always. Flares are intense bursts of radiation that happen along with reconnection events. CMEs, on the other hand, are the actual expulsion of material.
• Impact on Earth: If a CME is directed towards Earth, it can cause geomagnetic storms when it interacts with our planet’s magnetosphere. These storms can disrupt satellites, power grids, and cause auroras at lower latitudes.

The frequency of CMEs also varies with the Sun’s 11-year solar cycle. They are more common during periods of high solar activity.