GREENBELT, Md. -- NASA's sun-focused Solar Terrestrial Relations Observatory, or STEREO, twin spacecraft unexpectedly detected particles from the edge of the solar system last year. This helped scientists map the energized particles where the hot solar wind slams into the cold interstellar medium.

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STEREO has made possibly the first 3D measurements of a solar jet. Jets are columns of super hot plasma (hot ionized gases at over a million degrees) which shoot out from the sun over the course of just a few minutes - this one reached velocities of 300 km/s (650,000 miles/hour). It was over 10,000 kilometers high and nearly half as wide as the Earth.

STEREO observed it from two points of view 11 degrees apart. With these images it could be clearly seen that the jet was twisted. This twist is important. It agrees with models of jets in which they are caused by the twisting of magnetic field lines. Highly twisted magnetic fields eventually become unstable, much like an over-wound spring. When the writhing fields come into contact with nearby untwisted fields that extend into the solar wind, the twist is transferred to those very long field lines. The twist then rapidly leaves the Sun, pushing the plasma outward at high speed.