The radio emission seen here is an Einstein Ring, a dramatic demonstration of EinsteinΓÇÖs principle that because mass and energy can be considered equivalent gravity can affect energy as well as mass. Radio waves have no mass, but they do contain energy and, as the Einstein Ring demonstrates, can be affected by gravity. On a terrestrial scale, gravityΓÇÖs effect on radio or light waves cannot be measured, but in the vast distances of space, the effects are sometimes detectable.
The radio waves from this quasar are distorted, literally bent into a ring, by the gravity of a galaxy lying in front of the lobe (the galaxyΓÇÖs position is marked by the cross inside the ring).
