The Voyager 1 spacecraft, launched by NASA in 1977, crossed an unexpected region of space last August, a report published in the journal Science confirmed on Thursday.
The news was announced in December 2012, but the evidence has now been peer-reviewed.
The previously unknown territory is located within the heliosophere, a bubble around our solar system formed by a stream of charged particles blown out by our sun.
Voyager 1 entered an especially turbulent region of the heliosphere, called the heliosheath, in December 2004.
Scientists have dubbed this newly observed part of the helioshealth the "heliosheath depletion region."
This may be the last leg of the spacecraft's journey to interstellar space, the region between solar systems where the magnetic field of the Sun is no longer felt.
When that happens, Voyager 1 will become the first man-made object to exit our solar system.