Peter van de Kamp (1901–1995)

Peter van de Kamp died in suburban Amsterdam on 18 May 1995 at the age of 93, after a long career as an authority in the field of long-focus photographic astrometry. He was born in 1901 in Kampen, a picturesque walled city reminiscent of the days the town was a member of the Hansiatic League, in the north of Holland. Although his father had little education beyond elementary school he was well read, spoke several languages and rose to be an administrator in a local business. He played the organ in church and had a piano in the home. This is where the future astronomer found his love and talent for music which played a significant part in his life.

Van de Kamp started his astronomical studies at the University of Utrecht in The Netherlands in 1918, having determined that a career in music would be more difficult to achieve than one in astronomy. He was a "straight A student" with an interest in mathematics and cosmology. Following four years in Utrecht he became an assistant at the Kapteyn Astronomical Laboratory in Groningen, and this led to an invitation to come to the McCormick Observatory at the University of Virginia after he had gained a Ph.D. from the University of California, Berkeley, in 1925, as well as a similar degree at the University of Groningen. From 1925 to 1937 he pursued the study of stellar proper motions at the McCormick Observatory, where he produced data useful for the study of galactic structure. He also became interested in the question of the absorption of light in space as it affected the distance determinations of globular clusters.

In 1937 van de Kamp accepted a call to Swarthmore College as Associate Professor of Astronomy and Director of the Sproul Observatory. In 1940 he was appointed Professor, which he held until his retirement in 1972. During his tenure he became recognized internationally for his research in long-focus astrometry. Many of those working in the field of astrometry today were among his students. His first project at Swarthmore College was to initiate the Sproul Observatory's long range research emphasis on nearby stars, thus augmenting the reputation of Swarthmore for astronomical research in this branch of astrometry .

Capitalizing on previous astrometric photographs from the Sproul 60 cm. refractor, which were obtained primarily for trigonometric parallax determination, van de Kamp extended the program to include an extensive and intensive study of the stars in our stellar neighborhood. This pioneer study had as one of its major goals the discovery of low-mass stars to extend and refine the lower end of the mass-luminosity relation and to find out if other stars had planets. Visual detection being virtually impossible, any such discovery would be made by the gravitational pull of the planet on "its sun" giving rise to an observed wobble in the visible star's path across the plane of the sky. Fifty years ago, the subject of whether there were planets revolving around other stars was not the popular question that it is today, and the technology to pursue the notion was not as refined then. After several decades of research the star closest to the earth visible from northern latitudes, Barnard's Star, gave indications of a companion of very low mass. The amplitude of the deviation from linear proper motion as shown on the compilation of a long series of photographs taken with the Sproul 60 cm. refractor was very small and near the level of attainable accuracy. In the early 1960s van de Kamp announced that there was evidence that Barnard's star had a planetary companion with a mass similar to that of Jupiter, the most massive planet in our solar system. Later some slight confirming evidence came from other sources but was not conclusive, and with further studies, small discrepancies in the performance of the optics of the Sproul telescope over a period of time indicated that the "wobble" was spurious.

The Sproul research program initiated by van de Kamp has led to the discovery of a number of low-mass stellar companions to stars which augmented our knowledge of astrometric binaries with low-mass companion stars and also strengthened statistics indicating the prevalence of stellar duplicity in the galaxy. Also through the study of known double stars van de Kamp increased knowledge of stellar masses, one of the most fundamental parameters in the physical universe.

In the months immediately after the end of the war in Europe, van de Kamp became a member of the Alsos Mission under the Office of Scientific Research and Development, and was stationed in Paris, France. The group was officially committed to a study of the progress of science in Germany under the Nazis, which included gaining knowledge of Germany's progress in the construction of atomic bombs, guided missiles and radar. Making many collegial contacts there, he returned to Paris as Fulbright Professor in 1949.

During the 1950s and 1960s van de Kamp was influential in the professional organization of astronomy though various service positions. He was the first Program Director for Astronomy for the National Science Foundation, vice President of the AAAS and chairman of Section D. he was also Director-at-large on the Board of the Association of Universities for Research in Astronomy at the time they were charged with the planning and construction of the Kitt Peak National Observatory. He also was President of Commission 26 of the International Astronomical Union and a member of the U.S. National Committee. A gifted teacher, he was a participant in the Visiting Professor program sponsored by the NSF and the American Astronomical Society.

Between 1952 and 1981 van de Kamp authored a number of books and monographs including: Basic Astronomy; Elements of Astromechanics; Architecture of the Universe (with G. Honegger); Principles of Astrometry and Stellar Paths. Between 1940 and 1975 he was a visiting professor at graduate summer schools at Harvard, Wesleyan University and in France, as Fulbright Professor. He was an invited lecturer in Germany, Mexico and also in Moscow, Tbilisi and Leningrad in 1970.

Van de Kamp was a recipient of a number of awards and prizes: The President and Visitors Prize, U of Virginia; The Glover Award, Dickinson College; The Nason Award, Swarthmore College; The Rittenhouse Medal, The Rittenhouse Society of Philadelphia; Bude Award of the College de France; and the Janssen Medal of the French Astronomical Society. He was awarded membership in Sigma Xi, Phi Beta Kappa and Correspondent of the Royal Netherlands Academy of Science. In 1980 an asteroid was named in his honor. In 1974-5 van de Kamp was a Lecturer at the Astronomical Institute of Amsterdam and from that time on he was a frequent resident in Amsterdam and kept close contact with the Institute. He remained as Research Astronomer at the Sproul Observatory from 1972-76.

He was well known as a popular and witty lecturer in amateur circles. An accomplished musician, he directed an amateur orchestra in Charlottesville, Virginia prior to coming to Swarthmore, where be became Conductor of the Swarthmore College Orchestra. He also played violin and piano and was a published composer of works for the piano. An ardent admirer of Charlie Chaplin, van de Kamp amassed a significant collection of his films at a time when they were not generally available to the public in the United States. He showed these on designated evenings at Swarthmore College as "Charlie Chaplin Seminars." Often he accompanied these silent gems with his playing of appropriate piano music. At the time of the IAU Colloquium No 18 on Double Stars, held in Swarthmore, the closing dinner celebrated his 70th birthday, and he was presented with an original piano composition by Peter Schickele (alias P.D.Q. Bach) entitled "The Easy Goin' P.V.D.K. Ever Loving Rag."

Peter van de Kamp always expressed the belief that Astronomy was a marvelous synthesis of art and science, and he patterned his successful life in that fashion

Further information on the astronomical life and times of Peter van de Kamp can be found in an extensive oral history interview deposited in the Niels Bohr Library of the American Institute of Physics; aspects of his professional life are also nicely recorded in the educational film Invisible Universe. His research correspondence and general papers have been deposited at the Library of the United States Naval Observatory in Washington, DC.