Einstein ring
Sign in to saveAlso known as Chwolson ring, Einstein–Chwolson ring
an image of a distant light source (such as a galaxy or star) which has been distorted into a ring through gravitational lensing caused by an object with an extremely large mass (such as another galaxy or a black hole)
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Encyclopedic overview
Einstein ring, created by a nearer galaxy (NGC 6505) distorting light of a distant galaxy. Four images of the distant galaxy, corresponding to four bright spots, can be seen in this picture.
An Einstein ring, also known as an Einstein–Chwolson ring or Chwolson ring (named for Orest Chwolson), is created when light from a galaxy or star passes by a massive object en route to the Earth. Due to gravitational lensing, the light is diverted, making it seem to come from different places. If source, lens, and observer are all in perfect alignment (syzygy), the light appears as a ring.
Excerpted from Wikipedia’s “Einstein ring” article, available under the CC BY-SA 4.0 licence.