Latitude Variation of Flux and Impact Angle of Asteroid Collisions with Earth and the Moon

Abstract

Abstract Flux and impact angles were calculated for asteroid collisions with Earth and the Moon, using the latest population models for the distribution of near-Earth objects (NEOs) and precession models to determine the impact probabilities. The calculations predict that the flux of impacts to the poles for Earth is 22% greater than the flux at the equator, and 55% greater for the Moon. Impacts near the equator typically have shallower impact angles with a mode near 30° above the horizontal. Conversely, impacts near the poles are typically steep with a mode close to 65°. Our new analysis updates the previously published results by Le Feuvre & Wieczorek incorporating: (1) an updated debiased distribution of NEOs, and (2) updated collision probabilities that account for Lidov–Kozai precession. The new impact distributions provide an important update to risk models, showing a 7% increase in average population risks from sub-300 m impactors, compared to previous atmospheric entry distributions, mostly due to faster impact velocities.