Space probes show solar system dented, not round

Jul 2, 2008  4:07 PM (ET)

By SETH BORENSTEIN
Associated Press

http://apnews.myway.com//article/20080702/D91LU1J00.html


WASHINGTON (AP) - When viewed from the rest of the galaxy, the edge of our 
solar system appears slightly dented as if a giant hand is pushing one edge 
of it inward, far-traveling NASA probes reveal.

Information from Earth's first space probes to hit the thick edge of the 
solar system - called the heliosheath where the solar wind slows abruptly - 
paint a picture that is not the simple circle that astronomers long 
thought, according to several studies published Thursday in the journal 
Nature. Surprised astronomers said they will have to change their models 
for what the solar system looks like.

In 1977, NASA launched two space probes on missions beyond the solar 
system. Voyager 1 went north and Voyager 2 went south. What startled 
astronomers is that when the two of them hit the heliosheath they did so at 
different distances from the sun.

Voyager 2 hit the southern edge of the solar system nearly 1 billion miles 
closer to the sun than Voyager 1 did to the north. Voyager 2 hit the edge 
at 7.8 billion miles from the sun.

"We used to assume that it's all symmetric and simple," said Leonard 
Burlaga, an astrophysicist at NASA's Goddard Space Flight Center in 
Greenbelt, Md. "It's literally like a hand pushing."

That push is from the magnetic field that lies between star systems in the 
Milky Way. The magnetic field hits the solar system at a different angle on 
the south than on the north, probably because of interstellar turbulence 
from star explosions, said Voyager project scientist Ed Stone.

Both spacecraft still have several more years before they completely exit 
the solar system and continue deeper into the space between stars, said 
Stone, former director of NASA's Jet Propulsion Lab.

---

On the Net:

Nature: http://www.nature.com/nature


================================
George Antunes, Political Science Dept
University of Houston; Houston, TX 77204
Voice: 713-743-3923  Fax: 713-743-3927
antunes at uh dot edu

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