2 of 28Image
This image shows the path taken by Voyager 1. While in the heliosphere which is the edge of a bubble around our solar system it was boosted by solar winds that travel at "supersonic speeds until [they cross] a shockwave called the termination shock," according to NASA. This is the dark blue area that Voyager 1 entered in December 2004.
The heliosheath (gray) is where the solar wind slows down and heats up. When Voyager 1 passed this area, it encountered interstellar winds, indicating it left the solar system. The area where the interstellar wind meets the heliosphere is called a bowshock and is indicated by the yellow area.