Einstein ring

Part of a series of articles about
Gravitational lensing
Einstein ring Formalism Strong lensing Microlensing Weak lensing
Strong lens systems Abell 1689 Abell 2218 CL0024+17 Bullet Cluster QSO2237+0305 SDSSJ0946+1006 B1359+154 QSO 0957+561
Surveys Strong: CLASS SLACS SDSS Micro: OGLE Gaia Weak: DLS Pan-STARRS CFHTLS DES LSST SNAP DESTINY
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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.