This graphic shows the position of the Voyager 1 and Voyager 2 probes relative to the heliosphere, a protective bubble created by the Sun that extends well past the orbit of Pluto.
According to NASA, the spacecraft has started to detect the same increase in cosmic radiation that hit Voyager 1 just before it finally entered interstellar space. The Low-Energy Charged Particle instrument also detected an increase in higher energy cosmic rays. In order to Voyager 2 to leave the solar system it must pass through a heliopause so it is not an easy job to predict that, based on information from scientists. - We learn much in the coming months, but we still have no idea when we reach the heliopause.
Considering that Voyager 2 was not released at the same time as its predecessor or the same path, scientists can not predict when it will pass through the heliopause.
Signals indicate the NASA space probe could be nearing the edge of the heliosphere. The spacecraft has detected a spike in cosmic rays that is believed to have originated outside the Solar System.
An cosmic ray instrument on the probe had measured about a 5 percent increase in the rate of cosmic rays since late August, compared to early August.
If successful, Voyager 2 will become the second human-made object, after Voyager 1, to reach interstellar space.
Image NASA JPL-Caltech
Launched in 1977, Voyager 2 spacecraft is now nearly 11 billion miles from Earth or more than 118 times the distance between Earth and the Sun.
Voyager 2 is the only spacecraft to visit Uranus and Neptune.
Between them, Voyager 1 and 2 have explored all the giant outer planets of the solar system, 48 of their moons, and the unique systems of rings and magnetic fields those planets possess.
"We are seeing a change in the environment around "Voyager-2", there is no doubt, says project scientist Voyager ed stone, a physicist from Caltech".
Cosmic rays are fast-moving particles that originate outside the solar system.
Still, it's a remarkable achievement and, judging by growing cosmic rays - about a five per cent increase over two months - it's only a matter of time before the probe joins its companion in interstellar space. It is similar to a bubble around the solar system which expands and contracts. "We're not there yet - that's one thing I can say with confidence". However, this solar wind wanes every 11 years in accordance with the solar cycle.