This is an artist's concept illustrating the structures the solar wind forms around our Sun. As we fly out from the Sun beyond the orbits of the planets, we come to the termination shock (semi-transparent purple sphere). The termination shock is where the solar wind, a thin stream of electrically charged gas blown constantly from the Sun, is slowed abruptly by pressure from gas between the stars. Beyond this region is the solar system's final frontier - the heliosheath. The heliosheath is a vast region where the solar wind is turbulent and hot (dark purple area in Image 2). As the camera moves outward, we see the heliosheath on the largest scales. The interstellar wind collides with the heliosheath and forms a structure called the bow shock (red and orange areas), forcing the heliosheath into a long, teardrop shaped structure. This image shows the positions of the Voyager spacecraft in relation to these structures.
Image Credit: NASA/Walt Feimer