  Advancements in infrared IR open up the possibility to spatially resolve AGN
on the parsec-scale level and study the circumnuclear dust distribution,
commonly referred to as the "dust torus", that is held responsible for the type
1/type 2 dichotomy of AGN. We used the mid-IR beam combiner MIDI together with
the 8m telescopes at the VLTI to observe the nucleus of the Seyfert 2 galaxy
NGC 424, achieving an almost complete coverage of the uv-plane accessible by
the available telescope configurations. We detect extended mid-IR emission with
a relatively baseline- and model-independent mid-IR half-light radius of (2.0
\pm 0.2) pc \times (1.5 \pm 0.3) pc (averaged over the 8-13 {\mu}m wavelength
range). The extended mid-IR source shows an increasing size with wavelength.
The orientation of the major axis in position angle -27deg is closely aligned
with the system axis as set by optical polarization observations. Torus models
typically favor extension along the mid-plane at mid-IR wavelengths instead.
Therefore, we conclude that the majority of the pc-scale mid-IR emission
(>~60%) in this type 2 AGN originates from optically-thin dust in the polar
region of the AGN, a scenario consistent with the near- to far-IR SED. We
suggest that a radiatively-driven dusty wind, possibly launched in a puffed-up
region of the inner hot part of the torus, is responsible for the polar dust.
In this picture, the torus dominates the near-IR emission up to about 5 {\mu}m,
while the polar dust is the main contributor to the mid-IR flux. Our results of
NGC 424 are consistent with recent observations of the AGN in the Circinus
galaxy and resemble large-scale characteristics of other objects. If our
results reflect a general property of the AGN population, the current paradigm
for interpreting and modeling the IR emission of AGN have to be revised.
(abridged)
