PASADENA, Calif., June 28 (UPI) -- Voyager 1's journey to the solar system's edge has shown the mysterious region is even stranger than previously thought, U.S. researchers say.
The latest readings from the NASA space probe, 11 billion miles away from Earth, has scientists reconsidering long-held theories on the nature of the solar system and conditions along its cold, dark edge.
At that distance the sun's solar winds slow to a whisper while particles thrown across the galaxy by ancient supernovae wander into the solar system.
Scientists had assumed when Voyager exited the heliosphere, the vast bubble of magnetism surrounding the solar system, solar winds would become still, galactic cosmic rays would bombard Voyager from every angle and the direction of the magnetic field would change because it would be coming from interstellar space, not the sun.
But the latest readings from Voyagers instruments support none of those suppositions, scientists said.
Voyager has reported solar winds suddenly dropped by half, while the strength of the magnetic field almost doubled, and those values then switched back and forth five times before they became fixed.
"The jumps indicate multiple crossings of a boundary unlike anything observed previously," a team of Voyager scientists wrote in one a study.
Voyager did detect the expected increase in galactic cosmic rays but found at times the rays were moving in parallel instead of traveling randomly.
"This was conceptually unthinkable for cosmic rays," Stamatios Krimigis, a solar physicist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., told the Los Angeles Times. "There is no cosmic ray physicist I know who ever expected that they would not all be coming equally from all directions."
Whether Voyager 1 -- which launched in 1977 -- has truly left the solar system has been a matter of some debate, because scientists have come up with competing theories on what constitutes in outermost edge.
"We're not free yet," Krimigis said. "This is a new region that we didn't know existed. We have no road map, and we're waiting to see what's going to happen next."