Introduction: Paleoheliosphere versus PaleoLISM
  Speculations that encounters with interstellar clouds modify the terrestrial climate have appeared in the scientific literature for over 85 years. This article introduces a series of articles that seek to give substance to these speculations by examining the exact mechanisms that link the pressure and composition of the interstellar medium surrounding the Sun to the physical properties of the inner heliosphere at the Earth. 
Priscilla C. Frisch