Detection of a large amount of diffuse extraplanar dust in NGC 891

Significant discrepancies have been found between the dust masses derived from various tracers (optical/near-IR, far-IR/sub-millimeter observations, and the variation of dust attenuation with viewing angle). Here we report the first detection of the extended far-UV (FUV) and near-UV (NUV) haloes perpendicular to the galactic plane of NGC 891, which can be interpreted as scattered stellar light from the galactic plane. An additional ``geometrically thick'' dust disk, which contains about the same mass as the standard thin dust disk, is needed to reproduce the vertically extended UV profiles