Mapping the location of terrestrial impacts and extinctions onto the spiral arm structure of the Milky Way

High density regions within the spiral arms are expected to have profound effects on passing stars. Understanding of the potential effects on the Earth and our Solar System is dependent on a sufficient dynamic model of arm passage. Using a novel combination of data we derive a model of the timings of the Solar System through the spiral arms and the relationship to arm tracers such as methanol masers. This reveals that asteroid/comet impacts are significantly clustered near the spiral arms and within specific locations of an average arm structure. The end-Permian and end-Cretaceous extinctions are shown to be located within a small star formation region in two different arms. The start of the Solar System greater than 4.5 Ga occurs in the same region in a third arm. The model complements geo-chemical data in determining the relative importance of extra-Solar events in the diversification and extinction of life on Earth.