Observational confirmation of a circumsolar dust ring by the COBE satellite

Abstract

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 dust¹¹. 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 direction¹¹. This prediction is in both qualitative and quantitative agreement with the asymmetry in zodiacal light observed by the Infrared Astronomical Satellite (IRAS)^11,12, but the IRAS data alone are equivocal because of calibration uncertainties and sparse coverage of elongation angle¹². Here we report observations by the Diffuse Infrared Background Experiment¹³ (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.