  It is expected that the next generation of high-contrast imaging instruments
will deliver the first unresolved image of an extrasolar planet. The emitted
thermal infrared light from the planet should show no phase effect assuming the
planet is in thermal equilibrium. But the reflected visible light will vary
versus the phase angle. Here, we study the photometric variation of the
reflected light versus the orbital phase of a ringed extrasolar planet. We show
that a ring around an extrasolar planet, both obviously unresolved, can be
detected by its specific photometric signature. A simple quantitative model is
discussed, taking into account the basic optical and geometrical properties of
the ringed planet.
