John Stanley Plaskett

John Stanley Plaskett


Date of Birth
November 17, 1865
Date of Death
October 17, 1941

“Jack” Plaskett began his college education at age 24, while a mechanic employed by the University of Toronto physics department, and graduated at 33. He was one of the original staff of the Dominion Observatory in Ottawa in 1903. He designed an exceptionally efficient spectrograph for the 15-inch refractor and measured radial velocities and found orbits of spectroscopic binary stars. He successfully lobbied for and designed and supervised construction of the 72-inch reflector built for the new Dominion Astrophysical Observatory in Victoria and was appointed its first director in 1917. There he extended the work on radial velocities and spectroscopic binaries and studied spectra of O and B-type stars. He was able to confirm the Lindblad-Oort model of galactic rotation with these data, and he also did important work on interstellar calcium. He was a leader in building Canadian astronomy.

Presentation of Bruce medal

Joy, Alfred H., PASP 44, 5-20 (1932).

Other awards

American Academy of Arts & Sciences, Rumford prize, 1930.
National Academy of Sciences, Henry Draper medal, 1934.
Royal Astronomical Society, Gold medal, 1930, presented by A.C.D. Crommelin, MNRAS 90, 466-477 (1930).
Royal Society of Canada, Flavelle medal, 1932.

Some offices held

Royal Astronomical Society of Canada, President, 1914-15.

Biographical materials

Beggs, Mike, Canada Heirloom Series, John Stanley Plaskett — Canada's Father of Modern Astronomy
Broughton, R. Peter, Northern Star: J.S. Plaskett (Univ. of Toronto Press, 2018). [info]
North, J.D., Dictionary of Scientific Biography 11, 18-19.
Spencer Jones, H., Obituary Notices of Fellows of the Royal Society 4, 67-82 (1942).
Tenn, Joseph S., “John S. Plaskett: The Twenty-Seventh Bruce Medalist,” Mercury 24, 1, 34 (1995).


Aitken, Robert G., PASP 53, 323-24 (1941).
Beals, C.S., JRASC 35, 401-411 (1941)
Bok, Bart J., Science 94, 453 (1941).
Chant, C.A., “John S. Plaskett at the University of Toronto,” JRASC 35, 412-414 (1941).
Hogg, Frank S., MNRAS 102, 70-73 (1942).
Petrie, R.M., Popular Astronomy, 50, 1, 2-5 (1942).
Redman, R.O., Observatory 64, 207-211 (1942).
Sanford, R.F., Ap. J. 98, 137-141 (1943).


Herzberg Astrophysics

Named after him

Lunar crater Plaskett.
Minor Planet #2905 Plaskett (with his son, Oxford astronomer H.H. Plaskett).
Plaskett’s Star, long the most massive binary star system known.
The Plaskett Telescope at the Dominion Astrophysical Observatory.
Royal Astronomical Society of Canada and the Canadian Astronomical Society, The Plaskett Medal (more).


Papers, etc.

. There is more information about him in a 1978 oral history interview with his son, Oxford University astronomer Harry H. Plaskett.

Other References: Historical

The Dominion Astrophysical Observatory, Victoria, B.C.; A Sketch of the Development of Astronomy in Canada and of the Founding of This Observatory. (F.A. Acland, Ottawa, 1923).

Batten, Alan H., “Of Stars and the Galaxy,” JRASC 61, 241-56 (1967).

Crommelin, A.C.D., “The Astronomical Work of John S. Plaskett,” JRASC 24, 217 (1930).

Heard, John F. & Helen Sawyer Hogg, “Astronomy at the David Dunlap Observatory, JRASC 61, 257-76 (1967).

Hearnshaw, J. B., The Analysis of Starlight (Cambridge University Press, Cambridge, UK, 1986).

H[ogg], F[rank] S., “Memorial to Dr. J.S. Plaskett,” JRASC 37, 167-68 (1943).

Hogg, Helen Sawyer, “Memories of the Plaskett Era of the Dominion Astrophysical Observatory, 1931-1934,” JRASC 82, 328-335 (1988).

Hogg, Helen Sawyer, “The First Hundred Years of the Royal Astronomical Society of Canada,” Observer’s Handbook 1990, 1-3.

Hogg, Helen Sawyer, “Joseph Algernon Pearce, 1893-1988,” Trans. Royal Society of Canada V (1989).

Jarrell, R.A., The Cold Light of Dawn: A History of Canadian Astronomy (U. of Toronto Press, Toronto, 1988).

Jarrell, R.A., “The Birth of Canadian Astrophysics: J.S. Plaskett at the Dominion Observatory,” JRASC 71, 221-233 (1977).

Jarrell, Richard A. “The Instrument was Instrumental — Plaskett’s Telescope and Canadian Astronomy Between the Wars,” JRASC 87, 218-22 (1993).

Jarrell, R.A., “J.S. Plaskett and the Modern Large Reflecting Telescope," Journal for the History of Astronomy 30, 359-390 (1999).

Plaskett, J.S. “The Dominion Astrophysical Observatory,” PASP 39, 88-96 (1927).

Plaskett, J.S. “The History of Astronomy in British Columbia,” JRASC 77, 108-20 (1983) [previously published in the British Columbia Historical Quarterly in 1939].

Plaskett, Thomas S., “The History of the Plaskett Family,” JRASC 82, 6, 319-27 (1988) and introduction to this paper by R. Peter Broughton, p. 317-318.

Webb, George E., “Victoria Welcomes the Dominion Astrophysical Observatory: Science and Society in the Pacific Northwest,” Pacific Northwest Quarterly 94, 171-81 (Fall 2003).

Wright, K.O., “Astronomy in Canada,” JRASC 61, 211-217 (1967).

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Other References: Scientific

Beals, C.S., R.M. Petrie, & K.O. Wright, “A Bibliography of the Published Papers of J. S. Plaskett,” JRASC 35, 408-11 (1941).

Plaskett, J.S. “The Character of the Star Image in Spectrographic Work,” Ap.J. 25, 195-217 (1907) and 27, 139-51 (1908).

Plaskett, J.S., “The Spectrum of Mira Ceti,” JRASC, 1, 45-59 (1907).

Plaskett, J.S., “Adapting a Universal Spectroscope for Radial Velocity Determinations,” JRASC, 1, 104-121 (1907).

Plaskett, J.S. “Camera Objectives for Spectrographs,” Ap.J. 29, 290-300 (1909).

Plaskett, J.S., “The Design of Spectrographs for Radial Velocity Determinations,” JRASC, 3, 190-208 (1909).

Plaskett, J.S. & W.E. Harper, “Two Curiously Similar Spectroscopic Binaries,” Ap.J. 30, 373-82 (1909).

Plaskett, J.S., “Slit Widths and Errors of Measurement in Radial Velocity Determinations,” JRASC, 4, 333-44 (1910).

Plaskett, J.S., “The Plane Grating for Stellar Spectroscopy,” Ap.J. 37, 373-79 (1913).

Plaskett, J.S., “The Stellar Spectrograph of the 72-inch Reflecting Telescope,” Ap.J. 49, 209-23 (1919).

Plaskett, J.S., “The Spectroscopic Binary H. R. 8170,” JRASC 13, 174-78 (1919).

Plaskett, J.S., W.E. Harper, R.K. Young, & H.H. Plaskett, “One Hundred Spectroscopic Binaries,” Pubs. Dominion Astrophysical Observatory 1, 163-85 (1920).

Plaskett, J.S., “The H and K lines of calcium in O-type stars,” MNRAS 84, 80-93 (1923).

Plaskett, J.S., “A Very Massive Star,” MNRAS 82, 447-500 (1922).

Plaskett, J.S. “The O-Type Stars,” Pubs. Dominion Astrophysical Observatory 2, 285-356 (1924).

Plaskett, J.S. “The Optical Parts of the Victoria Spectrograph,” Ap.J. 59, 65-75 (1924).

Plaskett, J.S. “Three Peculiar Spectra,” Pubs. Dominion Astrophysical Observatory 4, 1-26 (1926).

Plaskett, J.S., “Note on Three Peculiar Spectra,” MNRAS 87, 31-34 (1926).

Plaskett, J.S., “The Rotation of the Galaxy,” MNRAS 88, 395-403 (1928).

Plaskett, J.S., “The Motions of the B Stars,“ Science 71, 225-30 (1930).

Plaskett, J.S. & J.A. Pearce, “The Motions and Distribution of Inter-stellar Matter,” [George Darwin Lecture] MNRAS 90, 243-68 (1930).

Plaskett, J.S., “The High-Temperature Stars,” (George Darwin Lecture), MNRAS 90, 616-635 (1930).

Plaskett, J.S. & J.A. Pearce, “The Radial Velocities of 523 O- and B-Type Stars Obtained at Victoria,” Pubs. Dominion Astrophysical Observatory 5, 1-98 (1931).

Plaskett, J.S. & J.A. Pearce, “A Catalogue of the Radial Velocities of O- and B-Type Stars,” Pubs. Dominion Astrophysical Observatory 5, 99-165 (1931).

Plaskett, J.S. “The Structure and Rotation of the Galaxy,” PASP 44, 141-66 (1932).

Plaskett, J.S. “Observational Confirmation of the Rotation of the Galaxy,” Observatory 56, 328–32 (1933).

Plaskett, J.S. & J.A. Pearce, “The Distance and Direction to the Gravitational Centre of the Galaxy from the Motions of the O5 to B7 stars,” MNRAS 94, 679 (1934).

Plaskett, John Stanley, The and Structure of the Galaxy; being the Halley lecture delivered on 5 June 1935. (The Clarendon Press, Oxford, 1935) [A summary appeared in JRASC 30, 153-64 (1936)].

Plaskett, J.S., “An Analysis of the K Term in the B-type Stars,” MNRAS 98, 518-27 (1938).

Plaskett, J.S. “The 82-inch Mirror of the McDonald Observatory,” Ap.J. 89, 84-98 (1939).

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Other Works: Popularizations, History, etc.

Plaskett, J.S., “Some Recent Interesting Developments in Astronomy,” JRASC 7, 448-55 (1913).

Plaskett, J.S., “The Sidereal Universe,” JRASC 9, 37-56 (1915) [President’s address].

Plaskett, J.S., “Modern Views of the Sun,” JRASC 10, 101-20 (1916) [President’s address].

Plaskett, J.S., “The 72-inch Reflecting Telescope,” PASP 30, 267-82 (1918).

Plaskett, J.S., “The Dimensions of the Stars,” PASP 34, 79-93 (1922).

Plaskett, J.S., “Luncheon to Dr. and Mrs. J. S. Plaskett,” JRASC 19, 247-54 (1925) [an account of his trip to England for the IAU meeting and other events].

Plaskett, J.S., “Sixty Years’ Progress in Astronomy,” JRASC 21, 295-310 (1927).

Plaskett, J.S., “A Review of the Progress of Astronomy,” PASP 44, 215 (1932).

Plaskett, J.S., “Modern Conceptions of the Stellar System,” Popular Astronomy 47, 239-55 (1939) [Presidential address to Pacific Division of AAAS, 1938].