  A new analytical 3D model of interstellar extinction within 500 pc of the Sun
as a function of the Galactic spherical coordinates is suggested. This model is
physically more justified than the widely used Arenou model, since it takes
into account the presence of absorbing matter both in the layer along the
equatorial Galactic plane and in the Gould Belt. The extinction in the
equatorial layer varies as the sine of the Galactic longitude and in the Gould
Belt as the sine of twice the longitude in the Belt plane. The extinction
across the layers varies according to a barometric law. It has been found that
the absorbing layers intersect at an angle of 17 deg and that the Sun is
located near the axial plane of the absorbing layer of the Gould Belt and is
probably several parsecs below the axial plane of the equatorial absorbing
layer but above the Galactic plane. The model has been tested using the
extinction of real stars from three catalogs.
