Einstein ring 爱因斯坦环
In observational astronomy an Einstein ring, also known as an Einstein-Chwolson ring or Chwolson ring, is the deformation of the light from a source (such as a galaxy or star) into a ring through gravitational lensing of the source's light by an object with an extremely large mass (such as another galaxy or a black hole). This occurs when the source, lens, and observer are all aligned. The first complete Einstein ring, designated B1938+666, was discovered by collaboration between astronomers at the University of Manchester and NASA's Hubble Space Telescope in 1998.