  The geometry of black hole spacetimes can be probed with exquisite precision
in the gravitational-wave window, and possibly also in the optical regime. We
study the accretion of bright spots -- objects which emit strongly in the
optical or in gravitational waves -- by non-spinning black holes. The emission
as the object falls down the hole is dominated by photons or gravitons orbiting
the light ring, causing the total luminosity to decrease exponentially as
${\cal L}_o\sim e^{-t/(3\sqrt{3}\,M)}$. Late-time radiation is blueshifted, due
to its having been emitted during the infall, trapped at the light ring and
subsequently re-emitted. These universal properties are a clear signature of
the existence of light rings in the spacetime, and not particularly sensitive
to near horizon details.
