Linearly polarized starlight is revealing the three-dimensional structure of the local
interstellar magnetic field (ISMF) surrounding the heliosphere, and hitherto unknown
aspects of the solar system's galactic environment. The polarization arises as starlight
traverses a dichroic interstellar medium formed by aligned interstellar dust grains. An
ongoing survey of the interstellar polarizations of nearby stars indicates that these data trace
(at least) three magnetic field directions: the ISMF direction of the center of the arc of the�…