Scientists say they believe this is the final region Voyager 1 has to cross before reaching interstellar space.
Voyager 1's instruments showed a five-fold increase in high-energy charged particles, accompanied by a 1,000-fold drop in low-energy particles, NASA officials said. These data would be consistent with Voyager 1's exit from the heliosphere, but Voyager 1's magnetic-field reading instrument indicates otherwise.
It shows an East-West magnetic field orientation, indicative of the sun's influence. The magnetic field in interstellar space, influenced by winds from explosions of supernovae, is thought to have a roughly North-South orientation, according to NASA astrophysicist Leonard Burlaga.