OBSERVATIONAL CONFIRMATION OF A CIRCUMSOLAR DUST RING BY THE COBE SATELLITE

ASTEROID collisions are an important source of the dust particles in the zodiacal cloud(1-3). These particles spiral in towards the Sun under the influence of drag forces(4-6) and, in passing through the inner Solar System, are subject to gravitational perturbations by the planets, which may trap them (at least temporarily) in orbital resonances(7-10). Recently, numerical simulations have shown that resonances with the Earth are particularly effective at trapping asteroidal dust, leading to the suggestion that the Earth may be embedded in a circumsolar ring of dust(11). The azimuthal structure of this ring was predicted to be asymmetric, with the region trailing the Earth being substantially more dense than that in the leading direction(11). This prediction is in both qualitative and quantitative agreement with the asymmetry in zodiacal light observed bg the Infrared Astronomical Satellite (IRAS)(11,12), but the IRAS data alone are equivocal because of calibration uncertainties and sparse coverage of elongation angle(12). Here we report observations by the Diffuse Infrared Background Experiment(13) (DIRBE) on the Cosmic Background Explorer satellite (COBE)(14), which confirm both the existence of this ring and the predictions of its near-Earth structure.