NASA's two Voyager spacecraft show nothing's simple at the edges of the solar system.
After a three-decade journey away from Earth, the two Voyager spacecraft are approaching the outer edges of the solar system. To scientists' surprise, the satellites have revealed a region vastly different than previously modeled. The solar system's boundary is defined by a steady stream of particles known as the solar wind. The solar wind shoots out from the sun until it pushes up against the galactic medium and slows down at a line called the termination shock. Beyond this lies the heliosheath, where the solar wind's journey stops completely. Scientists thought the solar wind turned back smoothly at this point, sweeping back around the outskirts of the solar system. As seen in the video below, Voyager now shows that solar wind hits the heliosheath and piles up into a frothy layer filled with magnetic bubbles. This layer must have an affect on how intense energetic particles from the rest of the universe, called cosmic rays, make it into our solar system. But scientists have yet to figure out if the bubbles help stop the bulk of the rays, or are the prime factor that allows them to enter.