On the possible relation between the Tunguska bolide and comet Encke

Almost two decades ago Ľ. Kresák (Bull. Astron. Inst. Czechoslov. 29, 129–134, 1978) suggested that the Tunguska bolide might be a fragment of comet Encke, a hypothesis that Z. Sekanina criticized in a publication a few years later (Astron. J. 88, 1382–1414, 1983). One aspect of the proposed genetic relationship is investigated, namely the required differential orbital precession of the two objects so as to make an impact upon our planet possible for the Tunguska projectile, even though the cometʹs orbit in the current epoch is far from the condition of Earth intersection. This work was foreshadowed in a previous paper in which it was shown how theoretical meteor radiants may be calculated for objects with orbits similar to 2P/Encke (Earth, Moon and Planets 68, 155–164, 1995). By applying appropriate secular perturbation theory and numerical integration techniques, it is shown that the necessary dispersion can be attained within 10 kyr if the semi-major axes of the orbits differ by ∼0.05 AU, an amount easily achieved even under the presently observed non-gravitational forces of 2P/Encke.