What are coronal mass ejections (CMEs) and why study them?
CMEs are powerful eruptions that can eject a small part of the sun’s atmosphere into interplanetary space. Typically, CMEs eject about one billion tons of solar particles into space and travel at about one million miles per hour. They can create major disturbances in the interplanetary medium (dust, gas and plasma in the space between the planets), and if they reach Earth, trigger severe magnetic storms that affect satellites, communications, power grids and airlines. CME-driven shocks also play a significant role in accelerating solar energetic particles that can damage spacecraft and harm astronauts. Despite their importance, scientists don’t fully understand the origin and evolution of CMEs. STEREO’s unique 3-D measurements should help with those answers. Understanding what causes CMEs and how they move through the solar system is one of the chief goals of the STEREO mission. The different telescopes in the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) instrum
