OBSERVATIONAL CONFIRMATION OF A CIRCUMSOLAR DUST RING BY THE COBE SATELLITE

ASTEROID collisions are an important source of the dust particles in t he zodiacal cloud(1-3). These particles spiral in towards the Sun unde r the influence of drag forces(4-6) and, in passing through the inner Solar System, are subject to gravitational perturbations by the planet s, which may trap them (at least temporarily) in orbital resonances(7- 10). Recently, numerical simulations have shown that resonances with t he Earth are particularly effective at trapping asteroidal dust, leadi ng to the suggestion that the Earth may be embedded in a circumsolar r ing 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 u ncertainties and sparse coverage of elongation angle(12). Here we repo rt observations by the Diffuse Infrared Background Experiment(13) (DIR BE) on the Cosmic Background Explorer satellite (COBE)(14), which conf irm both the existence of this ring and the predictions of its near-Ea rth structure.