THE CLOSE APPROACH OF STARS IN THE SOLAR NEIGHBORHOOD

We examine the kinematics of stars in the Solar Neighbourhood, and com pute their trajectories and distances of closest approach to the Sun. We find that Proxima has been the closest star to the Sun for the last 32 000 years, but will lose this status to the dwarf star Ross 248 in 33 000 years. We are approaching a period relatively rich in stellar encounters, with six stars all coming closer to the Sun than the curre nt distance of Proxima Centauri over the next 45 000 years. Only the c lose approach of alpha Cen A/B will have any detectable dynamical effe ct, however, perturbing the outer Oort Cloud and putting about 10(5) c omets into potentially Earth-impacting orbits.