The heliosphere—made of solar wind, solar transients, and the interplanetary magnetic field—acts as our solar system's personal shield, protecting the planets from galactic cosmic rays. These extremely energetic particles accelerated outwards from events like supernovas and would cause a huge amount of damage if the heliosphere did not mostly absorb them.

Currently, the scientific community cannot reach a consensus on the boundaries or contours of this protected space, and they're exploring mission concepts for an interstellar probe that travels beyond the sun's sphere of influence to answer these questions.