Hubble’s discovery had revolutionized humanity’s conception of its place in the world, and it is difficult to overestimate its long-term effects. Over three millennia, from an essentially local idea of Earth as a disc, the planet had become round and had been dislodged from its position at the center of the universe to be a mere satellite of a sun, which in turn had been found to be one of many in a galaxy of suns, the Milky Way. Now this galaxy was no longer a universe—the only universe—but merely one among countless galaxies in the immense, fathomless, and expanding darkness of space, and
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