  Over the recent past, the galactic environment of the Sun has differed
substantially from today. Sometime within the past ~130,000 years, and possibly
as recent as ~56,000 years ago, the Sun entered the tenuous tepid partially
ionized interstellar material now flowing past the Sun. Prior to that, the Sun
was in the low density interior of the Local Bubble. As the Sun entered the
local ISM flow, we passed briefly through an interface region of some type. The
low column densities of the cloud now surrounding the solar system indicate
that heliosphere boundary conditions will vary from opacity considerations
alone as the Sun moves through the cloud. These variations in the interstellar
material surrounding the Sun affected the paleoheliosphere.
