Page 15 of the April 2013 issue of Smithsonian magazine also reports that Voyager 1 has seen a rise in cosmic rays but does NOT interpret this as an indication that the spacecraft has left the heliosphere.

Also, as JohnD correctly states, even when Voyager exits the heliosphere, the spacecraft will still be firmly within the solar system. The Oort cloud has roughly a trillion objects BEYOND the heliosphere; all are orbiting the Sun and thus members of our solar system.

To quote from page 16 of the April 2013 Smithsonian, “Despite its swift speed, Voyager 1 is like a California-bound traveler who has walked just a few miles from the Atlantic seaboard.”

Voyager has a LONG way to go before it exits the solar system.

Best,
Mohi Kumar
Surprising Science Blog Editor

Which I further hope will be in the Smithsonian when one day we’ll finally develop the technology to go and fetch you back home!

NASA/JPL has released the following statement:

“The Voyager team is aware of reports today that NASA’s Voyager 1 has left the solar system,” said Edward Stone, Voyager project scientist based at the California Institute of Technology, Pasadena, Calif. “It is the consensus of the Voyager science team that Voyager 1 has not yet left the solar system or reached interstellar space. In December 2012, the Voyager science team reported that Voyager 1 is within a new region called ‘the magnetic highway’ where energetic particles changed dramatically. A change in the direction of the magnetic field is the last critical indicator of reaching interstellar space, and that change of direction has not yet been observed.”

First, and foremost, the heliopause is not a static boundary. Instead, it is formed by the interaction of the Sun’s magnetic field with the galactic field; as the Sun’s magnetic field changes, the heliopause moves back and forth. So Voyager 1 could be beyond the heliopause one day and back inside it another.

Second, even outside of the heliopause, there are literally tens of thousands of objects orbiting the Sun. These objects, which include Oort cloud members and plutoids such as Haumea, Eris, and Makemake.