Light bends around a massive object, such as a black hole, causing it to act as a lens for the things that lie behind it. Astronomers routinely use this method to study stars and galaxies behind massive objects.
The Einstein Cross, a quasar in the Pegasus constellation, according to the European Space Agency (ESA), and is an excellent example of gravitational lensing. The quasar is seen as it was about 11 billion years ago; the galaxy that it sits behind is about 10 times closer to Earth. Because the two objects align so precisely, four images of the quasar appear around the galaxy because the intense gravity of the galaxy bends the light coming from the quasar.In cases like Einstein's cross, the different images of the gravitationally lensed object appear simultaneously, but that isn't always the case. Scientists have also managed to observe lensing examples where, because the light traveling around the lens takes different paths of different lengths, different images arrive at different times, as in the case of one particularly interesting supernova.
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The Einstein Cross, a quasar in the Pegasus constellation, according to the European Space Agency (ESA), and is an excellent example of gravitational lensing. The quasar is seen as it was about 11 billion years ago; the galaxy that it sits behind is about 10 times closer to Earth. Because the two objects align so precisely, four images of the quasar appear around the galaxy because the intense gravity of the galaxy bends the light coming from the quasar.In cases like Einstein's cross, the different images of the gravitationally lensed object appear simultaneously, but that isn't always the case. Scientists have also managed to observe lensing examples where, because the light traveling around the lens takes different paths of different lengths, different images arrive at different times, as in the case of one particularly interesting supernova.