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Voyager 2 detects dent in solar system

December 11, 2007|John Johnson Jr. | Times Staff Writer

SAN FRANCISCO — Like a beat-up, high-mileage car, the solar system has a dent in it.

Scientists revealed Monday that data from the Voyager 2 spacecraft showed that the shell of solar gases that encircles our star system has been dinged up by passing through the rubble of stars that exploded millions of years ago.

Voyager 2, launched in 1977, just passed through what's known as the termination shock, the boundary of the bubble of energy carried by the solar wind to the far edge of the solar system.

The surprise was that Voyager 2 reached the barrier a billion miles closer to the sun than Voyager 1, its companion spacecraft that is taking a more southern path to interstellar space.

"Something outside is pushing in on the southern hemisphere" of the solar system, said Voyager project scientist Edward Stone of Caltech in Pasadena.

The results were released at the annual meeting of the American Geophysical Union in San Francisco.

Stone said the most likely candidate for the force that has dented the shell of energy around the sun, called the heliosphere, was the magnetic fields left over from supernovae that exploded 10 million to 20 million years ago in a region of the Milky Way Galaxy known as the Scorpius-Centaurus Association.

Scientists also found that Voyager 2 crossed the boundary layer several times over a few days.

Scientists described the boundary as more like a fluid tide, surging in on a beach and then retreating, than a rigid line of demarcation.

The scientists said the Voyagers had enough radioactive fuel remaining to operate their 20-watt transmitters until at least 2020, by which time they hope the spacecraft will have passed out of the outermost bubble around the solar system, known as the heliopause, and into true interstellar space.

The two Voyagers will be the first man-made objects to leave the sun's immediate neighborhood.

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