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Explanation: Most galaxies have a single nucleus -- does this galaxy have four? The strange answer leads astronomers to conclude that the nucleus of the surrounding galaxy is not even visible in this image. The central cloverleaf is rather light emitted from a background quasar. The gravitational field of the visible foreground galaxy breaks light from this distant quasar into four distinct images. The quasar must be properly aligned behind the center of a massive galaxy for a mirage like this to be evident. The general effect is known as gravitational lensing, and this specific case is known as the...

Because of the lensing effect of a massive galaxy located between this supernova and the telescope imaging it, the same explosion showed up four times around the galaxy. This formation is called an Einstein Cross. Einstein first predicted the phenomenon of gravitational lensing (a result of his theory of relativity) about a century ago. Astronomers have seen Einstein Crosses made by galaxies and black holes before, but this is the first time they've seen a supernova jump into the shot. In this case, the supernova -- which is 9 billion light years away -- would be too faint to be...