`Great Debate:' Obituary of Harlow Shapley

This obituary was reprinted from Nature, Vol. 240, pp 429-430 (1972) with permission. Copyright 1972 by Nature. Written by Z. Kopal.

NATURE Obituary


Dr Harlow Shapley

With the passing, on October 20, 1972, of Dr Harlow Shapley less than two weeks before his 87th birthday, the world astronomical community has lost one of its outstanding leaders in the first half of the 20th century; and (by the time of his death) also one of the last survivors of its heroic age which saw the 19th century solar-system astronomy (almost) "break the barriers of the heavens" - an effort in which Shapley took a prominent part.

Born on November 2, 1885, in Nashville, Missouri, in the rural mid-west of the United States, Shapley was deflected to study astronomy almost by accident (from professional journalism), though he remained a successful writer for the rest of his life. His academic career led him through the University of Missouri (AB in 1910, AM in 1911) where he came under the influence of Frederick H. Seares (1873-1964) - and subsequently to Princeton, then being a rejuvenated under the new administration of President Woodrow Wilson, with young Henry Norris Russell (1877-1957) at the head of its astronomy department.

The time when Shapley came to Princeton could not have been more propitious. Shortly before, Russell embarked on a new approach to the analysis of the light curves of eclipsing variables in quest of the properties of constituent stars. The arrival of a research student of Shapley's calibre was a godsend to the subject as well as to Russell himself; for thousands of observations were by 1912 awaiting analysis. Russell - aided by his never-absent slide-rule, and unimpeded by any excess of mathematical sophistication - was the guide; but without Shapley's energy in applications the new methods would not have got off the ground. Shapley's energy 1914 PhD thesis on the orbits of 90 eclipsing binaries virtually created in one stroke a new branch of double-star astronomy.

Having received his doctorate, Shapley joined the staff of the Mount Wilson Observatory in California. Fortune smiled on him (and on astronomy) when George Ellery Hale (1868-1936) offered him a research post at one of the few institutions in the United States where such positions were available at that time; and Shapley made ample use of his opportunity. His scientific interests shifted from eclipsing variables - a field in which he retained lasting interest, but to which he never really returned - to globular star clusters; and with their aid he made, in 1918, what was to become his greatest single contribution to science: namely, the discovery of the dimensions of our Galaxy, and of the location of its centre.

That the distribution of such clusters in the sky is highly asymmetric (most of them are situated in one hemisphere) was known long before Shapley's time: as well as the fact that many of them contain large numbers of cepheid variables whose absolute brightness can be estimated from the periods of their light changes. Armed with this evidence, Shapley embarked on systematic study of the distribution of the globular clusters in space; and found its center to be located some 50,000 light years from us, in the direction of the galactic longitude 325o in the constellation of Sagittarius. This point Shapley boldly identified with the centre of our entire Galaxy; and he was indeed right. As a result of his work, our Galaxy began to emerge for what it actually is: a stellar system at least ten times as large as all earlier estimates - from Herschel to Kapteyn - made it out to be; with our Sun located eccentrically some 15 thousand parsecs from its centre.

This latter distance was, to be sure, somewhat overestimated; for by 1918 Shapley was not yet aware of the absorption of light which a concentration of gas and dust close to the galactic place exerts on distant objects at low galactic latitudes. The role of this "interstellar fog" did not transpire more fully until the 1930s, and it diminished our actual distance from the galactic centre from 15 to 9 thousand parsecs; but the order of magnitude of Shapley's earlier estimate remained unaltered.

The years 1914-1921, which Shapley spent at Mount Wilson, mark, in retrospect, the high noon of his scientific life; but Shapley did not distinguish himself only in research. Soon the world - and not only the astronomers - learned to know him as an outstanding lecturer and successful writer; in addition, Hale's example helped to develop Shapley's innate talents for administration. Small wonder that - in 1920 - Shapley was offered directorship of the Harvard College Observatory, when the latter fell vacant on the death of E. C. Pickering (1846-1919). Shapley accepted; and this observatory was to remain his academic home for the rest of his life.

Under Shapley's energetic direction, the observatory's equipment was rapidly modernized, the Arequipa Southern Station transferred to become the Boyden Station in South Africa, and domestic observational activities were relegated from the proximity of the Harvard yard to the new Oak Ridge (later, Agassiz) Station some 30 miles west of Cambridge. Both the Oak Ridge and Boyden Stations were provided with new 60-inch reflectors and (in the last decade of Shapley's directorship) also with modern Schmidts. But perhaps the greatest - and certainly the most fruitful - of Shapley's innovations was the establishment of the graduate school of astronomy as a part of the educational structure of Harvard University. This school became a great success; and a list of its graduates reads like a Who's Who in astronomy today.

All these activities inevitably raised considerable demands on Shapley's time, but never made him abandon active work in galactic and extragalactic research. After he left Mount Wilson, Shapley no longer had reflectors as large as those on the West Coast within his research. His telescopes at Harvard possessed smaller apertures, but wider angular fields. It was with these that Shapley and his collaborators continued to explore the Magellanic clouds, to probe the spatial distribution of external galaxies; and (in 1938) discovered new dwarf galaxies in Sculptor and Fornax - discoveries which augmented the known population of the inner metagalaxy in an unexpected manner.

Then World War II came; and with it a sequence of changes the end of which is nowhere in sight. At its end in 1945, Shapley was 60 years age; and as an "elder statesman" of science he was called upon to perform many extracurricular duties - such as to preside of the American Astronomical Society, the American Association for the Advancement of Science, and the National Society of Sigma Xi, almost in succession. All these duties took much of his time from the observatory and from more creative work. As a result, the last seven years of Shapley's term of office as director of the Harvard Observatory were not, perhaps, marked by the same elan as the decade preceding them; and his observatory gradually yielded its leading position to others.

Shapley's retirement from directorship in 1952 (he continued to serve as research professor until 1956) brought to a close an era which kept Harvard Observatory in the forefront of astronomy progress 75 years under the administration of two outstanding directors - a record unequalled in the annals of astronomy. Unlike his predecessor, E. C. Pickering, who died in office, Shapley survived his retirement for another 20 years; and saw the directorship of his observatory change hands no less than three times. He continued to be active as a lecturer and author for some time after 1956; but his creative powers slowly waned; and he died peacefully on October 20 of this year in Boulder, Colorado, while on a visit to his son. He is survived by his wife Martha Betz Shapley - his faithful collaborator already from the Princeton days, and as gracious a hostess as ever presided over the social life of any observatory, keeping her own and no small scientific abilities largely under a bushel - and five children, all of whom have been active in further development of science. Moreover, Shapley's talents as a scientist and writer are already in evidence among his grandchildren as well.

Harlow Shapley was an outstanding man of his time - astronomer, educator, author, orator, as well as man of affairs. Some of his gifts, displayed prominently in the course of his life, may gradually fall in oblivion as those of us who knew him in his prime may no longer be here to remember; and dust may settle on some of his work, or on many honours bestowed upon him by his contemporaries. But one title to fame will never tarnish - Shapley's discovery of the centre of our Galaxy, and of our position within it.

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