A century ago, the Milky Way galaxy was the entirety of the known universe. We had no idea what made the stars shine, and only one star — our own sun — was known to harbor any planets. Of those planets, humans had explored only one: Earth.
“The stellar universe, as we know it … is a flattened, watch-shaped organization of stars and nebulae,” astronomer Harlow Shapley wrote in Science News Bulletin, the earliest version of Science News, in August 1921 (SN: 8/8/1921, p. 3). That sparkling pocket watch was the Milky Way, and at the time Shapley wrote this, astronomers were just beginning to conceive that anything at all might
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