Our solar system is a series of bubbles within bubbles – plasma within magnetic fields separated from each other by huge, flowing sheets of electric currents. It's a pattern that's repeated throughout the rest of our plasma universe. The Sun is enclosed in a magnetic bubble. As the solar wind streams outward, pulling the Sun's magnetic field with it, it forms a huge, teardrop-shaped magnetic bubble. This bubble, the heliosphere, contains the solar wind, the entire solar magnetic field, and all the planets (many with their own magnetic fields). At the outermost boundary of the heliosphere, called the heliopause, the solar wind meets the interstellar medium, a plasma that permeates our Milky Way galaxy. Sometime in the next few decades, the Pioneer and Voyager spacecraft will finally cross this distant frontier. The heliosphere is thought to be around 100 times the distance from Earth to the Sun (100 AU) – For comparison, Pluto is about 40 AU from the Sun.