On Monday, project officials said new information sent back from the ship yielded a surprising result.
"If we would have only looked at particle data alone, we would have said we're out of the solar system," said Tom Krimigis, a scientist from Johns Hopkins University who examines data on low-energy charged particles. "But nature is very imaginative, and Lucy pulled up the football again."
The Voyager team believes this region is where lines of magnetic particles from the solar system are meeting particles from interstellar space.
Because the direction of the magnetic lines is unchanged, the project members count this as part of the solar system. When the direction changes, Voyager 1 will finally be in interstellar space.
"We believe this is the last leg of our journey to interstellar space," said project member Edward Stone of the California Institute of Technology. "Our best guess is it's likely just a few months to a couple years away. The new region isn't what we expected, but we've come to expect the unexpected from Voyager."
The spacecraft entered the new region in July, fueling predictions it was getting close to the edge of the solar system.
Voyager 2, which is on a different flight path, is a few billion miles closer to the sun.
