Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. Without a telescope, even this immense spiral galaxy appears as an unremarkable, faint, nebulous cloud in the constellation Andromeda . But a bright yellow nucleus, dark winding dustlanes, gorgeous blue spiral arms and star clusters are recorded in this stunning telescopic digital mosaic of the nearby island universe. While even casual skygazers are now inspired by the knowledge that there are many distant galaxies like M31, astronomers seriously debated this fundamental concept only 80 years ago. This question was central to the famous Shapley-Curtis debate of 1920, which was later resolved by observations of M31 in favor of Andromeda, island universe .
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