  We perform and analyze global Particle-in-Cell (PIC) simulations of the
interaction between solar wind and an outgassing comet with the goal of
studying the plasma kinetic dynamics of a cometary environment. To achieve
this, we design and implement a new numerical method in the iPIC3D code to
model outgassing from the comet: new plasma particles are ejected from the
comet "surface" at each computational cycle. Our simulations show that a bow
shock is formed as a result of the interaction between solar wind and outgassed
particles. The analysis of distribution functions for the PIC simulations shows
that at the bow shock part of the incoming solar wind, ions are reflected while
electrons are heated. This work attempts to reveal kinetic effects in the
atmosphere of an outgassing comet using a fully kinetic Particle-in-Cell model.
