IT STANDS out like a neon sign in the centre of the image, a thin blue arc floating over a golden-red blob. The blob is a giant elliptical galaxy six billion light years from Earth in the constellation Fornax. The arc above it is an illusion - a cosmic mirage created as the light from a young blue galaxy up to 10 billion light years away is dragged into a semicircular shape by the golden-red giant's gravity.
Captured in 2003 by the Hubble Space Telescope, this is just one of many stunning gravitational lens images that decorate the sky. Gravitational lenses are nature's giant telescopes, giving glimpses of what lies beyond the edge of the visible universe.
But look at them in the right way and these shining, candy-coloured arcs offer more than just distorted snapshots of young galaxies. They can also tell us about the age of the cosmos ...
18:00 23 July 2008
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