The heliosphere

The heliosphere is the big magnetic bubble in space carved out by the solar wind. The solar defines the border between our Solar System and interstellar space. This border, called the heliopause, is where the solar wind's strength is no longer great enough to push back the wind originating from other stars. The region around the heliopause also acts as a shield for our Solar System, warding off a significant portion of the cosmic rays outside the galaxy.

Latest data from Ulysses show that the Sun has reduced its output of solar wind to the lowest levels since accurate readings have become available. This current state of the Sun could reduce the natural shielding that envelops our Solar System.