Abstract

The effect of stellar flybys on planetary bodies within our solar system is relatively unknown.
Research suggests that changes in Earth’s orbit can affect the climatic evolution on our planet.
These cycles, dubbed the Milankovitch cycles, have been cited as playing a role in the
extinction events in Earth’s history. There is the potential that long term consecutive stellar
flybys could alter the Milankovitch cycles. This may be a contributing factor in the extinction
events that are associated with the crossing of the spiral arms. This study presents the effects
of 34 flyby scenarios on the Earth’s eccentricity and inclination evolution. A number of
REBOUND simulations were run over a 15 Myr period, passing stars of various masses at a
variety of encounter distances, locations, and inclinations. The numerical models show that
although many cases have little impact on the evolution of Earth’s eccentricity and inclination
cycles, that coplanar flybys at distances < 50000 AU can change these cycles significantly.
The results suggest that consecutive close encounters of stars to our solar system can perturb
Earth’s orbit. Therefore, it is plausible that stellar flybys may influence the Milankovitch
cycles and play a role in mass extinction events on Earth.