| Term: | Coronal Mass Ejection |
| Definition: |
An outflow of plasma from or through the solar corona. CMEs are often, but not always, associated with erupting prominences, disappearing solar filaments, and/or flares. CMEs vary widely in structure, density, and velocity. Large and fast CMEs can approach masses of 1.6 × 10^12 kg and approach velocities over 2000 km/s. Earth impacting CMEs can result in significant geomagnetic storms. Types of coronal mass ejections launched toward Earth are called "halo CMEs" because as they approach Earth, they appear larger than the Sun, making a halo of bright coronal emission completely around it. |