Satellite spies magnetic 'rubber band'

A drawing of the Wind satellite

By Richard Stenger
CNN

(CNN) -- The chance run of a NASA spacecraft through an electrified eddy in space could help explain how mighty eruptions of solar particles zero in on our planet.

Physicists have long been puzzled by the magnetic attraction between the Earth and sun. For decades, they theorized that magnetic fields between the two often short circuit and reconnect.

That interaction allows waves of ions and electrons from the sun to wind along solar magnetic field lines and slide like beads onto terrestrial ones. The charged particles work their ways to the poles of the Earth, where they spark dazzling aurora displays, the reasoning goes.

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Suspecting that the Wind satellite passed through a region where the sun-Earth magnetic lines interact, scientists from NASA, Japan and the University of California, Berkeley decided to peruse the corresponding data. Their findings will be published in the July 26 edition of the journal Nature.

"Most people believe magnetic reconnection happens as a way for solar particles to get inside our magnetosphere, but how?" said Cal-Berkeley researcher Marit Oieroset.

"With Wind, we have been lucky. This is the first time a spacecraft has flown through and observed the small region where the magnetic field lines actually reconnect. We are seeing this important physical process in action for the first time."

Such reconnections take place throughout the universe wherever magnetic fields interact, scientists speculate. One likely spot is the atmosphere of the sun, where the magnetic disturbances unleash solar flares, some directed toward our planet.

"We believe that reconnection is common in the universe because charged particles and magnetic fields exist everywhere. Ninety-nine percent of matter in the universe is in the form of plasma, a hot gas of charged particles and magnetic fields," Oieroset said.

Launched in 1994, Wind was positioned between the sun and Earth to study the relationship between the solar wind and the magnetosphere, the zone in space shielded by Earth's magnetic fields.

In 1999, NASA mission controllers decided to move the satellite to the shaded side of the planet. During the course change, Wind by chance zipped right through the area of magnetic reconnection, the scientists said.