Twilight data obtained photographically from a stratospheric balloon platform in the autumns of 1980 and 1981 and in the spring of 1982 are presented for blue and red light. They indicate the presence of a light absorbing layer and of a scattering layer in the mesosphere at altitudes near 60 ± 10 km with a low scattering albedo (0.1) at 0.44 μm if it is accepted that both the extinction and scattering originate from dust. The optical efficiency of the layer increases more than 10 times when the wavelength of the interacting light changes from 0.65 to 0.44 μm. At the zenith and near sunset, the natural 0.44-μm extinction optical thickness and the cm2 column scattering rate due to this layer are found to be 6.6 × 10-2 and 0.18 MR Å -1 respectively on 3 May 1982 above the south-west of France.