NASA’s spacecraft observes one of the fastest solar wind on record

Washington -  On July 23, 2012, NASA’s Solar TErrestrialRElations Observatory (STEREO) spacecraft observed a massive cloud of solar material, which erupted off the Sun’s right side and  zoomed out into space passing along its way.

Using the STEREO data, scientists at NASA’s Goddard Space Flight Center in Greenbelt, Md. clocked this giant cloud, known as a coronal mass ejection, or CME, as travelling between 1,800  and 2,200 miles per second as it left the Sun.

This was the fastest CME ever observed by STEREO, which since its launch in 2006 has helped make CME speed measurements much more precise.

Such an unusually strong bout of space weather gives scientists an opportunity to observe how these events affect the space around the Sun, as well as to improve their understanding of  what causes them.

“Between 1,800 and 2,200 miles per second puts it without question as one of the top five CMEs ever measured by any spacecraft. And if it’s at the top of that velocity range it’s probably the  fastest,” said solar scientist Alex Young at Goddard.

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.

On July 23, STEREO-A lay -- from Earth’s perspective -- to the right side and a little behind the Sun, the perfect place for seeing this CME, which would otherwise have been hard to measure  from Earth.

The Solar and Heliospheric Observatory (SOHO), an ESA and NASA mission, also observed the CME. It is the combination of observations from both missions that helps make scientists  confident in the large velocities they measured for this event.