Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. Here a very distant QSO happened to be placed right behind a massive galaxy . The gravitational effect of the galaxy on the distant QSO was similar to the lens effect of an empty wine glass on a distant street light - it created multiple images. These stars make the images change brightness relative to each other. These brightness changes are visible on these two photographs of the Einstein Cross , taken about 3 years apart.
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