AN EXTRATERRESTRIAL INFLUENCE DURING THE CURRENT GLACIAL-INTERGLACIAL

Evidence is presented for a category of inner Solar System fragmentati on events involving substantially devolatilized cometary bodies which not only give rise to dust singularities responsible for tails, antita ils and trails but also provide the bulk of the fragile meteoroidal ma terial reaching the Earth. The most prominent of these events are appa rently associated with a swarm of such bodies that moves within the 7: 2 Jovian mean motion resonance. Assuming the material released by thes e events perturbs the atmospheres of Sun and Earth attention is drawn to modulations of the climate during the late Pleistocene-Holocene (i. e. since similar to 20000 sp) which are in accordance with the growth pattern and cosmogenic signature of the bristlecone pine and appear to be due to the swarm and its source. It follows that the solar-terrest rial relationship may be largely sustained by dust erosion events. To facilitate further astronomical study, we tabulated forthcoming encoun ters with the swarm and give a short term orbit for the putative sourc e, emphasizing that in the longer term the orbit is essentially chaoti c and not reliably predicted. We indicate the likely character of the source in the past and consider also the future celestial hazard to ci vilization.