NASA wrote:June 9, 2011: NASA's Voyager probes are truly going where no one has gone before. Gliding silently toward the stars, 9 billion miles from Earth, they are beaming back news from the most distant, unexplored reaches of the solar system.

Mission scientists say the probes have just sent back some very big news indeed.

It's bubbly out there.

"The Voyager probes appear to have entered a strange realm of frothy magnetic bubbles," says astronomer Merav Opher of Boston University. "This is very surprising."

Nasa's Voyager 1 has entered uncharted territory on the border of our solar system and the remainder of the Milky Way.

Scientists at the US space agency said the craft had gone into a region at the edge of the solar system, describing it as "a kind of cosmic purgatory".

Ed Stone, Voyager project scientist at the California Institute of Technology in Pasadena, said: "Voyager tells us now that we're in a stagnation region in the outermost layer of the bubble around our solar system … We shouldn't have long to wait to find out what the space between stars is really like."

The Voyager 1 spacecraft is on course to be the first human-made object to leave the solar system, although Nasa expects it will be several months or even a few years before it completely enters interstellar space. Voyager 2, which is now 9bn miles away from the sun, will follow later.