  Events which meet certain criteria from star tracker images onboard the Juno
spacecraft have been proposed to be due to interplanetary dust particle impacts
on its solar arrays. These events have been suggested to be caused by particles
with diameters larger than 10 micrometers. Here, we compare the reported event
rates to expected dust impact rates using dynamical meteoroid models for the
four most abundant meteoroid/dust populations in the inner solar system. We
find that the dust impact rates predicted by dynamical meteoroid models are not
compatible with either the Juno observations in terms of the number of star
tracker events per day, or with the variations of dust flux on Juno's solar
panels with time and position in the solar system. For example, the rate of
star tracker events on Juno's anti-sunward surfaces is the largest during a
period during which Juno is expected to experience the peak impact fluxes on
the opposite, sunward hemisphere. We also investigate the hypothesis of dust
leaving the Martian Hill sphere originating either from the surface of Mars
itself or from one of its moons. We do not find such a hypothetical source to
be able to reproduce the star tracker event rate variations observed by Juno.
We conclude that the star tracker events observed by Juno are unlikely to be
the result of instantaneous impacts from the Zodiacal Cloud.
