30 years since it was launched in 1977, Voyager 2 reached and crossed the edge of our solar system where the solar wind still manages to push back against the interstellar wind particles that try to enter it. This boundary is called the termination shock front and the space that it defines is called the heliosphere.

Voyager 1 already crossed this boundary in 2004, but some of its sensors had failed before the probe got to the termination shock, so scientist weren’t able to get enough information about the physical phenomena that take place in that region. Because of this, Voyager 2 remained the scientists’ only hope to gather that kind of information for many years to come.

After analyzing the data that was sent back to earth by the probe, researchers made some very interesting findings. First of all, Voyager 2 crossed the termination shock about 1 billion miles closer to the sun, confirming the theory of some scientists that the heliosphere is egg-shaped, and not round as others considered it should be. One explanation for this is given by the differences in the magnetic field of our galaxy, which are supposedly caused by star explosions.

The discovery that shattered what scientists thought about the termination shock is that it seems to fluctuate. Up until now, the common perception was that it should stay at all times in the same position in space, but Voyager 2 passed through it several times. Another phenomenon that puzzled researchers was solar wind slowing down for apparently no reason before reaching the zone where it collides with interstellar particles.

Both Voyager 1 and Voyager 2 are expected to enter the interstellar region in about 10 years. At this moment they are both travelling through the heliosheath, the region of space where solar wind and interstellar particles both manifest their influences.