Around a century ago, astronomers believed our Milky Way encompassed the entire universe. Then Henrietta Swan Leavitt's work on Cepheid variable stars and
Around a century ago, astronomers believed our Milky Way encompassed the entire universe. Then Henrietta Swan Leavitt’s work on Cepheid variable stars and Edwin Hubble’s observations revealed that the mysterious “nebulae” scattered across the night s... [9763 chars]