The structured zodiacal light: IRAS, COBE, and ISO observations

The zodiacal light, once thought to be a simple phenomenon, to be easily removed from large-scale sky maps, has been found to be structured in many ways. The relatively smooth cloud cloud that dominates the emission is azimuthally asymmetric about the Sun and tilted with respect to the ecliptic, requiring a large number (> 13) of parameters for a moderately successful model. At least 5 asteroidal dust-bands have been detected, contributing some 10% of the zodiacal light, and on smaller scales at least 8 cometary dust trails have been detected. The emissivity of interplanetary grains is evidently not grey, nor is the albedo independent of wavelength, and recent ISO observations have revealed a possible spectral feature at 10 mu m.