NASA - National Aeronautics and Space Administration

STEREO Creates First Images of the Solar System's Invisible Frontier

> Larger image GREENBELT, Md. -- 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.

The two STEREO spacecraft were launched in 2006 into Earth's orbit around the sun to obtain stereo pictures of the sun's surface and measure magnetic fields and ion fluxes associated with solar explosions.

Mapping the region by means of neutral, or uncharged, atoms instead of light "heralds a new kind of astronomy using neutral atoms," said Dr. Robert Lin, professor of physics at the University of California, Berkeley.

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Twisting Solar Jets in STEREO

> Larger image Coronal jets are small-scale transient ejections of hot gases, or plasma, occurring in the solar atmosphere. During a typical event, about a million tons of matter are ejected at speeds reaching a million miles per hour over a few minutes' time. The jets are believed to contribute significantly to the mass flow constantly ejected by the Sun, known as the solar wind. Despite their relative simplicity, jets may serve as a paradigm for more complex and far larger events originating in the solar atmosphere, such as coronal mass ejections.

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About STEREO

STEREO (Solar TErrestrial RElations Observatory) is the third mission in NASA's Solar Terrestrial Probes program (STP). This two-year mission, launched October 2006, will provide a unique and revolutionary view of the Sun-Earth System. The two nearly identical observatories - one ahead of Earth in its orbit, the other trailing behind - will trace the flow of energy and matter from the Sun to Earth. They will reveal the 3D structure of coronal mass ejections; violent eruptions of matter from the sun that can disrupt satellites and power grids, and help us understand why they happen. STEREO will become a key addition to the fleet of space weather detection satellites by providing more accurate alerts for the arrival time of Earth-directed solar ejections with its unique side-viewing perspective.