gravitational lensgravitational lens
a massive celestial body, esp. a galaxy or cluster of galaxies, having enough gravity to refract light waves from a more distant object, esp. a quasar, so that an observer sees an amplified or multiple image (gravitational lensing)
A massive object whose gravitational field redirects or bends light rays.
Abell 2218, a cluster of galaxies in the constellation Draco
(plural gravitational lenses)