  The recent close approach of comet C/2020 F3 (NEOWISE) allowed us to study
the morphology of its inner coma. From the measurement of the dust ejection
velocityon spiral structures expanding around the nucleus, we estimated a mean
deprojectedexpansion velocity Vd= 1.11+/-0.08 km s^-1. Assuming that a new
shell formed after every rotation of the comet, a rotation period of 7.8+/-0.2
hours was derived. The spin axis orientation was estimated at RA 210+/-10d,
Dec. +3+/-10d. The comamorphology appears related to two strong, diametrically
opposite emissions located at mid-latitudes on the nucleus. A qualitative
modelling of the coma produced consistent results with a wide range of dust
sizes (0.80 to 800 micro-m), with inversely correlated densities (0.003 to 3.0
g cm^-3). Images taken with Vj and r-Sloan filters showed a greater
concentration of dust in the first two shells, and an increasing density of
radicals emitting in the B and V band-passes from the third shell outwards.
Striae-like structures in the tail suggest that dust particles have different
sizes.
