Letter to the Editor

Strong chaos induced by close encounters with Ceres and Vesta

J. Laskar¹, M. Gastineau¹, J.-B. Delisle¹, A. Farrés¹ and A. Fienga^1,2

¹ ASD, IMCCE-CNRS UMR 8028, Observatoire de Paris, UPMC, 77 Av. Denfert-Rochereau, 75014 Paris, France
e-mail laskar@imcce.fr
² Observatoire de Besançon – CNRS UMR 6213, 41bis Av. de l’Observatoire, 25000 Besançon, France

Received: 17 June 2011
Accepted: 7 July 2011

Abstract

We consider the full Solar System including(1) Ceres and some of the main asteroids, (2) Pallas, (4) Vesta, (7) Iris, and (324) Bamberga. We show that close encounters amongthese small bodies induce strong chaotic behavior in their orbits and in those of many asteroids that are much more chaotic than previously thought. Even if space missions will allow very precise measurements of the positions of Ceres and Vesta, their motion will be unpredictable over 400 kyr. As a result, it will never be possible to recover the precise evolution of the Earth’s eccentricity beyond 60 Myr. Ceres and Vesta thus appear to be the main limiting factors for any precise reconstruction of the Earth orbit, which is fundamental for the astronomical calibration of geological timescales. Moreover, collisions of Ceres and Vesta are possible, with a collision probability of 0.2% per Gyr.