Solar System Dented, Not Round

July 2, 2008 -- Millions of textbooks depicting our solar system as spherical have got it all wrong, according to studies of data sent back from deep space by NASA's venerable probe, Voyager 2.

The sun's zone of influence -- called the heliosphere -- turns out to be seriously asymmetrical, not round, they say.

The heliosphere comprises space dominated by the solar winds, or particles blasted out by the Sun. It goes way beyond the orbit of Pluto, which circles the sun at a distance of nearly four billion miles.

Launched in 1977 on a historic trek of the outer planets, Voyager 2 has now crossed the turbulent boundary, known as the "termination shock," where the heliosphere yields to interstellar space.

Its twin probe Voyager 1, crossed the same threshold four years earlier at a different spot some one billion miles farther from the sun.

This difference proves that the heliosphere is not even close to perfectly round, but is oblong, like an egg, according to the studies, released by the British journal Nature on Wednesday.

The "bottom" of the egg is flattened by a permanent clash of particles, as the outbound solar wind smashes into atomic debris hurtling in from interstellar space, the scientists theorize.

Voyager 2 also crossed the "termination shock" several times within the space of a single day, showing that the boundary is in perpetual flux, like the ebb-and-flow of a tide.

University of Arizona astronomer Randy Jokipii paid tribute to the two Voyagers, which have been operating faithfully since their launch in 1977.