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.

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.