  The time-dependent metric of a cosmic string leads to an effective
interaction between the string and photons - the "gravitational Aharonov-Bohm"
effect -- and causes cosmic strings to emit light. We evaluate the radiation of
pairs of photons from cosmic strings and find that the emission from cusps,
kinks and kink-kink collisions occurs with a flat spectrum at all frequencies
up to the string scale. Further, cusps emit a beam of photons, kinks emit along
a curve, and the emission at a kink-kink collision is in all directions. The
emission of light from cosmic strings could provide an important new
observational signature of cosmic strings that is within reach of current
experiments for a range of string tensions.
