On 23 July 2012, NASA’s Stereo **Mission spacecraft recorded a coronal mass ejection (CME). The cloud of solar material ejected from the Sun sped out into space at a speed of “between 1,800 and 2,000 miles per second”. That translates to about 7.2 million miles per hour or about 1.1% of the speed of light. NASA says it is probably the fastest CME ever measured by any spacecraft. Incredibly, it is said that, on average, the mass ejected into space is 1.6×1012kg. A video of the 23 July CME can be seen by clicking here.
From the NASA announcement of this event:
“Measuring a CME at this speed, traveling in a direction safely away from Earth, represents a fantastic opportunity for researchers studying the sun’s effects. Rebekah Evans is a space scientist working at Goddard’s Space Weather Lab, which works to improve models that could some day be used to improve predictions of space weather and its effects. She says that the team categorizes CMEs for their research in terms of their speed, with the fastest ones – such as this one — labeled “ER” for Extremely Rare.”
**The STEREO mission consists of two spacecraft with orbits that for most of their journey give them views of the sun that cannot be had from Earth. Watching the sun from all sides helps improve our understanding of how events around the sun are connected, as well as gives us glimpses of activity we might not otherwise see.