British and American astronomers have discovered a cosmic mirage caused when the gravity of a distant galaxy distorts the light coming from an object even further away. Our science correspondent David Whitehouse reports.

The remarkable object was discovered by the radio telescopes at the Jodrell Bank radio observatory in northern England. Searching the sky for distant galaxies that give off radio waves Jodrell astronomers discovered a strange object that appeared to be smeared across the sky.

Follow up observations made by the Hubble Telescope in orbit around the Earth showed that the object was the first known example of an "Einstein Ring."

More than 80 years ago Albert Einstein, in his theory of gravity, suggested that a massive object could deflect any light passing by it. The galaxy would act as a "gravitational lens" distorting and focusing light in much the same way that a glass lens would.

The Einstein Ring

The first cosmic gravitational lens was discovered by Jodrell Bank astronomers almost 20 years ago but this latest one is the closest to a perfect circle.

There is an almost exact alignment between the nearby galaxy and the distant object that means that its image is distorted into a ring. Astronomer Professor Mark Birkinshaw said: "We have scored a bulls-eye!"

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