As Earth orbits the Sun, the Solar System itself revolves around the center of the Milky Way, moving through a continuously changing Galactic environment. In addition to its mean orbital motion, the Solar System has a peculiar velocity relative to the surrounding gas and stars, causing it to traverse different regions of the interstellar medium (ISM) over time. The ISM spans a wide range of gas and dust densities, temperatures, and pressures, and is continuously shaped by processes such as supernova explosions, stellar winds and radiation, Galactic shear, and magnetic fields.
Encounters with dense gas structures, such as molecular clouds or supernova shock fronts, may have measurable consequences for the Solar System. For instance, an enhanced influx of interstellar dust into the Solar System and Earth’s atmosphere during such encounters could induce radionuclide anomalies in terrestrial archives. Similar signals may also be produced by nearby supernovae through an enhancement of the cosmic-ray flux. In addition, increased extraterrestrial dust may alter Earth’s radiative balance, and it remains a matter of debate whether this could result in detectable climatic responses. Under sufficiently high ambient gas densities, the heliosphere itself could be compressed, potentially exposing parts of the Solar System directly to the ISM.
Recent advances in astronomy, geochemistry, and paleoclimatology underscore the timeliness of studying these processes. In astronomy, the European Space Agency’s Gaia mission has revolutionized our view of the local Galactic environment, enabling the identification of previously unknown large-scale gas structures and stellar associations or clusters, as well as their relation to the Solar System’s past trajectory. In geochemistry, improved analytical techniques and expanding datasets have revealed anomalies in radionuclide and interplanetary dust records, some already linked to astrophysical events and others still unexplained. In paleoclimatology, new high-resolution proxy records and Earth system model simulations of past climates are becoming available. Together, these developments open new opportunities to explore connections between Galactic, Solar, and Terrestrial environments.
This meeting aims to characterize the past and future Galactic environments encountered by the Solar System, investigate potential links between these environments and changes in the Earth system, constrain the conditions under which interstellar densities and close supernovae can produce radionuclide anomalies or enhanced extraterrestrial particle fluxes, and foster interdisciplinary collaboration across astronomy, geology, and paleoclimatology.