Word: shapleys
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Last week, at an Amherst, Mass, meeting of the American Astronomical Society, Harvard's famed Astronomer Harlow Shapley demoted the Milky Way. It is a big galaxy, he said, but no bigger than many others...
...Shapley explained that astronomers have long had doubts about the yardstick they use to measure the enormous distances between the galaxies. It is based on Cepheid variable stars, whose luminosity (and therefore whose distance) can be told from their periods of pulsation. The system worked all right for a while, but recently many contradictions have shown up. For instance, the globular star clusters in the Magellanic Clouds (small, comparatively nearby galaxies) seemed to be much fainter intrinsically than similar clusters in the Milky Way. This offended the astronomers' sense of order. They felt that the clusters in both galaxies...
...Shapley's new scale of measurement will have a far-reaching effect on existing astronomical cosmologies. According to his findings, the universe is twice as old as was previously thought; its creation probably occurred between three and four billion years...
...Shapley also believes that the Milky Way, our own galactic system, can no longer be ranked as the largest galaxy. The famed spiral nebula in Andromeda now appears to be at least as large and is actually 1,500,000 light years away, twice as far as the previous figure...
...Shapley bases his conclusion chiefly on observations of the globular clusters found within the Magellanic Clouds, companion galaxies to the Milky Way. His scale resolves discrepancies in the brightness of the clusters which had long been a source of difficulty to astronomers...