Voyager may already left solar system for interstellar space

Nasa's long-lived Voyager probe probably crossed into interstellar space last year, becoming the first man-made object to leave the solar system, research suggests.

Scientists had been waiting for Voyager to detect a magnetic field that flows in a different direction to the solar system's magnetic field, but those behind the new research say that scenario is not accurate.

"We think that the magnetic field within the solar system and in the interstellar are aligned enough that you can actually pass through without seeing a huge change in direction," University of Maryland physicist Marc Swisdak said.

That would mean that Voyager reached interstellar space last summer, when it detected a sudden drop in the number of particles coming from the sun and a corresponding rise in the number of galactic cosmic rays coming from interstellar space.

Not everyone is convinced, however.