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NASA's STEREO leads to first detailed images of solar wind structures

August 19, 2011 - Washington

Scientists at Southwest Research Institute and the National Solar Observatory have developed the first detailed images of solar wind structures as plasma and other particles from a coronal mass ejection (CME) travelled 93 million miles and impacted Earth, thanks to NASA's STEREO spacecraft.

The images from a December 2008 CME event reveal an array of dynamic interactions as the solar wind, travelling at speeds of up to a million miles per hour, shifts and changes on its three-day journey to Earth, guided by the magnetic field lines that spiral out from the Sun's surface.

Observed structures include the solar wind piling up at the leading edge of a CME, voids in the interior, long thread-like structures, and rear cusps.

"For the first time, we can see directly the larger scale structures that cause blips in the solar wind impacting our spacecraft and Earth," said SwRI's Dr. Craig DeForest, lead author of the study.

"There is still a great deal to be learned from these data, but they are already changing the way we think about the solar wind," he stated.

Co-author Dr. Tim Howard, also of SwRI, added, "For 30 years, we have been trying to understand basic anatomy of CMEs and magnetic clouds, and how they correspond to their source structures in the solar corona.

"By tracking these features through the image data we can establish what parts of a space weather storm came from which parts of the solar corona, and why," he stated.

In particular, the new images reveal the shape and density of Jupiter-sized clouds of material in the so-called empty space between planets; in contrast, in-situ probes such as the WIND and ACE spacecraft reveal immense detail about the solar wind, at a single point in space.

The breakthrough was released online in an Astrophysical Journal.


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