  The increasing sensitivity of cosmic microwave background (CMB) missions will
require to significantly improve the accuracy in the subtraction of the various
sources of Galactic foreground, from the most relevant components (synchrotron,
dust and free-free emission) to those usually considered of minor relevance in
CMB experiments. With respect to other Galactic diffuse components, the
Zodiacal Light Emission (ZLE) is peculiar, depending not only on the observing
direction but also on the location of the observer within the Solar System: ZLE
behaves then as a large scale, time-dependent foreground. Starting from the
existing far-infrared ZLE models, we discuss the impact of ZLE contribution in
CMB maps and the level of contamination in time ordered data and maps expected
from the forthcoming Planck space mission as well as the Planck capability to
increase our knowledge of the ZLE properties.
