Einstein ring

noun1

1. •
   A ring-shaped gravitational mirage; an image of a distant light source, such as a galaxy, which has been distorted into a ring by a gravitational lens.

   • Thus, clusters of galaxies with masses M ∼ 10¹⁵M_⊙ at cosmological distances can result in Einstein rings with angular radii tens of arcseconds. — 2008