The Journey of the Sun

An analysis of the distribution and kinematics of interstellar material within 500 pc of the Sun leads to the conclusion that the galactic environment of the Sun changes with time. Consideration of evidence for interstellar gas interacting with the solar wind implies that these variations may alter the interplanetary environment of the Earth. The events causing the 10Be spikes 33,000 years and 60,000 years ago in the Antarctic ice record must be associated with the Local Fluff cloud complex, possibly due to solar encounters with structures with subparsec scale sizes. An encounter with "dense" interstellar cloud material could attenuate the solar L-alpha flux by as much as 70%, modify mesospheric chemistry, modify the magnetosphere-solar wind coupling, and alter the global electrical circuit. Prior to the entry of the Sun into the Local Fluff cloud complex, within the past 200,000 years, the galactic environment of the Sun differed radically from the environment prevailing today and expected for the near future.