Einstein ring
An Einstein ring is a phenomenon where the light from a distant object, such as a galaxy or quasar, is bent into a ring shape by the gravitational field of a massive foreground object, like another galaxy. This effect is a consequence of Einstein's theory of general relativity.
Source: hyperphysics.phy-astr.gsu.edu
APODs including "Einstein ring"
The Very Large Array of Radio Telescopes
28/05/2002
The most photogenic array of radio telescopes in the world has also been one of the most productive. Each of the 27 radio telescopes in the Very Large Array (VLA) is the size of a house and can be moved on train tracks. The above pictured VLA, celebrating its twenty-second year of operation, is situated in New Mexico, USA. The VLA has been used to discover water on planet Mercury, radio-bright coronae around ordinary stars, micro-quasars in our Galaxy, gravitationally-induced Einstein rings around distant galaxies, and radio counterparts to cosmologically distant gamma-ray bursts. The vast size of the VLA has allowed astronomers to study the details of super-fast cosmic jets, and even map the center of our Galaxy. An upgrade of the VLA is being planned.