  It has been proved that the general relativistic Poynting-Robertson effect in
the equatorial plane of Kerr metric shows a chaotic behavior for a suitable
range of parameters. As a further step, we calculate the timescale for the
onset of chaos through the Lyapunov exponents, estimating how this trend
impacts on the observational dynamics. We conclude our analyses with a
discussion on the possibility to observe this phenomenon in neutron star and
black hole astrophysical sources.
