Voyager surfs Solar System's edge

"It could be any day, but it could also be several more years."

Ed Stone cannot say when the Voyager-1 spacecraft will leave the Solar System, but he believes the moment is close.

The latest data from this extraordinary probe, reported in this week's Science journal, suggests it is surfing right on the very edge of our Sun's domain.

The particles streaming away from our star have reduced to a trickle at its present location, 18.5 billion km from Earth.

Particles flying towards it from interstellar space, by contrast, have jumped markedly in the past year.

It all points to an imminent departure, which would make Voyager the first man-made object to cross into the space between the stars.

- bbc.co.uk