A ring-shaped distortion of light from a galaxy caused by gravitational lensing, while this galaxy passes behind another massive object.
It is sometimes also referred to as the Chwolson ring, named after a Soviet scientist Orest Chwolson, who mentioned this phenomenon in his article (in English, his surname is usually transcribed as Khvolson, however, German transliteration Chwolson is used instead, since his article was first published in a German academic journal).
Etymology
The phenomenon is named after Albert Einstein, who predicted it in his theory of general relativity.
