Harlow Shapley

After graduation, Shapley received a fellowship to Princeton University for graduate work, where he studied under Henry Norris Russell and used the period-luminosity relation for Cepheid variable stars (discovered by Henrietta Swan Leavitt) to determine distances to globular clusters. He was instrumental in moving astronomy away from the idea that Cepheids were spectroscopic binaries, and toward the concept that they were pulsators.[9]

He realized that the Milky Way Galaxy was far larger than previously believed, and that the Sun's place in the galaxy was in a nondescript location. This discovery supports the Copernican principle, according to which the Earth is not at the center of our Solar System, our galaxy, or our Universe.

Shapley participated in the "Great Debate" with Heber D. Curtis on the nature of nebulae and galaxies and the size of the Universe. The debate took place on April 26, 1920, in the hall of the United States National Academy of Sciences in Washington DC. Shapley took the side that spiral nebulae (what are now called galaxies) are inside our Milky Way, while Curtis took the side that the spiral nebulae are 'island universes' far outside our own Milky Way and comparable in size and nature to our own Milky Way. This issue and debate are the start of extragalactic astronomy, while the detailed arguments and data, often with ambiguities, appeared together in 1921.[10]

Characteristic issues were whether Adriaan van Maanen had measured rotation in a spiral nebula, the nature and luminosity of the exploding novae and supernovae seen in spiral galaxies, and the size of our own Milky Way. However, Shapley's actual talk and argument given during the Great Debate were completely different from the published paper. Historian Michael Hoskin says "His decision was to treat the National Academy of Sciences to an address so elementary that much of it was necessarily uncontroversial.", with Shapley's motivation being only to impress a delegation from Harvard who were interviewing him for a possible offer as the next Director of Harvard College Observatory.[11] With the default by Shapley, Curtis won the debate. The astronomical issues were soon resolved in favor of Curtis' position when Edwin Hubble discovered Cepheid variable stars in the Andromeda Galaxy.[12][13]

At the time of the debate, Shapley was working at the Mount Wilson Observatory, where he had been hired by George Ellery Hale. After the debate, however, he was hired to replace the recently deceased Edward Charles Pickering as director of the Harvard College Observatory (HCO).

He is also known to have incorrectly opposed Edwin Hubble's observations that there are additional galaxies in the universe other than the Milky Way. Shapley fiercely critiqued Hubble and regarded his work as junk science. However, after he received a letter from Hubble showing Hubble's observed light curve of V1, he withdrew his criticism. He reportedly told a colleague, "Here is the letter that destroyed my universe." He also encouraged Hubble to write a paper for a joint meeting of the American Astronomical Society and American Association for the Advancement of Science.[12] Hubble's findings went on to reshape fundamentally the scientific view of the universe.[13]

Despite having earlier argued strongly against the idea of galaxies other than our Milky Way, Shapley went on to make significant progress in the research of the distribution of galaxies, working between 1925 and 1932. In this time period, with the Harvard College Observatory, he worked to map 76,000 galaxies. One of the first astronomers to believe in the existence of galaxy superclusters, Shapley later discovered and found a rather notable, very large and distant example - which would in 1989 be named Shapley Supercluster. He had estimated the distance to this supercluster at 231 Mpc, which is within 15% of the currently accepted value.

He served as director of the HCO from 1921–1952. During this time, he hired Cecilia Payne, who, in 1925, became the first person to earn a doctorate at Radcliffe College in the field of astronomy, for work done at Harvard College Observatory.

From 1941 he was on the original standing committee of the Foundation for the Study of Cycles. He also served on the board of trustees of Science Service, now known as Society for Science & the Public, from 1935–1971.

In the 1940s, Shapley helped found government funded scientific associations, including the National Science Foundation. He is also responsible for the addition of the "S" in UNESCO (United Nations Educational, Scientific and Cultural Organization).

On November 14, 1946, Shapley appeared under subpoena by the House Un-American Activities Committee (HUAC) in his role as member of the Independent Citizens Committee of the Arts, Sciences and Professions (ICCASP), which HUAC described as a "major political arm of the Russophile left". It had opposed re-election of U.S. Representative Joseph William Martin Jr. during mid-term elections that year and was asked to answer questions about the ICCASP's Massachusetts' chapter. HUAC committee chairman John E. Rankin commented about Shapley's attitude, "I have never seen a witness treat a committee with more contempt" and considered contempt of Congress charges. Shapley accused HUAC of "Gestapo methods" and advocated for its abolition, saying that it had made "civic cowards of many citizens" by pursuing the "bogey of political radicalism."[2][14]

A few weeks later, in early 1947, Shapley became President of the American Association for the Advancement of Science (AAAS). At the time, the AAAS's choice appeared to be a "rebuke" of HUAC and a positive championing of scientists.[2] In his inaugural address, Shapley referred to the danger of the "genius maniac" and proposed the elimination of "all primates that show any evidence of signs of genius or even talent".[15] Other global threats he listed were: drugs that suppressed the desire for sex; boredom; world war with weapons of mass destruction; a plague epidemic.[16]

In 1950, Shapley was instrumental in organizing a campaign in academia against Worlds in Collision by Russian expatriate psychiatrist Immanuel Velikovsky. Scientists generally considered this controversial US bestseller to be pseudoscience.