This animation illustrates how the constant outflow of particles from the sun, called the solar wind, interacts with the surrounding interstellar medium (ISM). Where the outflow first encounters the ISM, it forms a shockwave called the termination shock--the boundary that Voyager 2 just crossed. It is now in the intermediate zone, called the heliosheath, where the two regions interact. Within the next few years, it will cross another boundary, called the heliopause, where the sun's influence ends.

More: MIT instrument finds surprises at solar system's edge

Video animation / John Belcher and Mark Bessette, MIT