False color imaging of a solar flare. U.S. National Aeronautics and Space Administration (NASA).

Coronal mass ejections (CME) are explosive and violent eruptions of charged, magnetic field-inducing particles and gas from the Sun's outer coronal layer. The ejection from the Sun's corona can be massive (e.g., estimates of CME mass often range in the billions of tons. Ejections propel particles in specific directions, some directly crossing Earth's orbital position, at velocities up to 1200 miles per second (1,931 km per second) or 4,320,000 miles per hour in an ionized plasma (also known as the solar wind). Solar CMEs that are Earth directed disrupt and distort Earth's magnetic field and result in geomagnetic storms.

Although the solar wind is continuous, CMEs reflect large-scale increases in wind (i.e., particle) mass and velocity that are capable of generating geomagnetic storms.

Solar coronal ejections...