Abstract
This chapter describes the discovery of the two moons of Mars, Phobos and Deimos, made in 1877 by Asaph Hall using the giant 26-in. refractor at the U. S. Naval Observatory. Subsequent research over the next century is briefly highlighted, most notably the secular acceleration of Phobos, leading to claims of its artificial nature. A renaissance in moons of Mars studies came with robotic space missions beginning in the 1970s. The description of the discovery of Phobos and Deimos presented here is based on a manuscript discovered by the author in the U. S. Naval Observatory archives, as well as on Hall’s published work. Hall read the manuscript before Washington Philosophical Society on February 16, 1878, 6 months after the discovery of the two moons.
Keynote address at the First International Conference on the Exploration of Phobos and Deimos, held November 5–7, 2007 at NASA Ames Research Center in Mountain View, California, published here for the first time.
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Notes
- 1.
The future astronomer’s father, sometimes designated Asaph Hall II, died in 1842. His grandfather, who served in the Revolutionary War, was Asaph Hall I. The astronomer was therefore Asaph Hall III, and his son (also to become an astronomer) was Asaph Hall IV, although neither used the nomenclature. Asaph Hall IV was appointed an Assistant Astronomer at the USNO on July 27, 1889. He would become a Professor of Mathematics in February, 1908.
- 2.
Among the numerous obituaries see especially (Pritchett 1908). For a view of Asaph and his wife, see the biography of Mrs. Hall by their son Angelo Hall (Hall 1908, as well as Percival Hall (1945), and Journal of the National Science Club (March, 1899), 1–6. The Asaph Hall papers, comprising six boxes of material and approximately 1000 items, are located at the Library of Congress.
- 3.
- 4.
The report of the Melbourne Observatory for this period shows that its “Great Reflector” was used in a search for satellites of Mars, but the observers did not see them, MNRAS, 38 (1877–78), 188–89.
- 5.
See also (Hall 1878a, 4) and the 26-in. log book, Aug. 10–11, 1877, Naval Observatory Library.
- 6.
26-inch logbook, August 17, 1877, USNO Library.
- 7.
26-inch logbook, August 18, 1877, USNO Library; Hall (1878b, 6).
- 8.
Hall to Rodgers, Aug. 19, 1877, USNO Archives. Next to the date, Hall wrote “1600 hours,” which, since the astronomical day was then reckoned from noon, refers to 4 am.
- 9.
Clearly the discovery caught the imagination of the normally staid Hall. Noting that the angle subtended from Earth by the outer satellite of Mars was about.031 s of arc, Hall calculated that at the distance of our Moon this angle would correspond to 187 ft. on the Moon’s surface. “Hence, if we assume that the diameter of six miles is nearly correct it appears that the proposition of a German astronomer to establish on the plains of Siberia a system of fire signals for communicating with the inhabitants of the Moon is by no means a chimerical project.” In the year that Schiaparelli would begin the great Mars controversy with his observations of canali, it is interesting to see Hall sizing up the prospects of this scheme, attributed to K. F. Gauss, for communication with lunar inhabitants!
- 10.
While one might think (as most astronomers do) that Phobos is “fear” and Deimos “flight,” Blunck (1982) has the definitions the other way around. In fact classicist sources such as Crowell’s Handbook of Classical Mythology agree that Phobos means “panic,” “flight,” or “rout,” while Deimos means “fear” or “terror.” Thus there is some confusion between astronomers and classicists on this matter.
- 11.
Shklovskii first proposed the idea in 1959.
- 12.
Inexplicably, Sharpless does not cite Nautical Almanac Office Director Edgar W. Woolard’s article of the previous year (Woolard 1944), nor did Woolard cite the work of his Naval Observatory colleagues Burton and Sharpless. See Pascu (1978). In contrast to Phobos, Sinclair finds the results for an acceleration of Deimos “barely significant.”
References
Blunck, Jurgen. 1982. Mars and its Satellites: A Detailed Commentary on the Nomenclature. Exposition Press, Smithtown, N.Y., p, 151
Burns, J. A. 1978. “The Dynamical Evolution and Origin of the Martian Moons,” in Symposium on the Satellites of Mars, Vistas in Astronomy, 22, 193–210.
Burton, H. A. 1929. “Elements of the Orbits of the Satellites of Mars,” AJ, 155–164.
Dick, Steven J. 1988. “Discovering the Moons of Mars,” Sky and Telescope (September, 1988), 242–243.
Gingerich, Owen. 1970. “The Satellites of Mars: Prediction and Discovery,” JHA, 1 (Aug., 1970), 109–115
Gingerich, Owen. 1972. “Asaph Hall,” Dictionary of Scientific Biography, Charles Gillespie, ed., vol. 6, 48–50
Gould, S. H. 1945. “Gulliver and the Moons of Mars,” Journal of the History of Ideas, vi (1945), 91–101.
Hall, Angelo. 1908. An Astronomer’s Wife: The Biography of Angeline Hall. Baltimore
Hall, Asaph. 1878a. “Discovery of the Satellite of Mars,” manuscript in U. S. Naval Observatory Archives, read before Washington Philosophical Society February 16, 1878, p. 1.
Hall, Asaph. 1878b. Observations and Orbits of the Satellites of Mars, with Data for Ephemerides in 1879. Washington, U. S. Naval Observatory.
Hall, Asaph. 1878c. MNRAS, volume 38 (1877-8), pp. 205–209.
Hall, Percival 1945. Asaph Hall: Astronomer, A Biographical Sketch of Asaph Hall, 3d [1945], privately printed and distributed by its author.
Hill, George W. 1908. “Biographical Memoir of Asaph Hall, 1829-1907,” BMNAS, 6, Washington, 243–309.
NASA. 1988. Exploration Studies Technical Report, Washington, DC: NASA https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19890007336.pdf
Nature, Aug 23, 1877a, 341
Nature. Sept 6, 1877b, 397–98
Nature, Sept. 13, 1877c, 427–28
Pascu, Dan. 1978. “A History of the Discovery and Positional Observation of the Martian Satellites, 1877-1977, Vistas in Astronomy, 22, 141–148.
Pritchett, Henry S. 1908. Popular Astronomy (Feb, 1908), 66–70
Scientific American, 1877. Sept. 8, 1877, p. 1.
Seidelmann, P. K., ed. 1978. The Satellites of Mars, special issue of Vistas in Astronomy, vol. 22.
Sharpless, Bevan P. 1945. “Secular Accelerations in the Longitudes of the Satellites of Mars,” AJ, 51, 185–186.
Shklovskii, I. S. and Carl Sagan. 1966. “Are the Moons of Mars Artificial Satellites?”, in Intelligent Life in the Universe. Holden-Day: San Francisco, pp. 362–376.
Sinclair, A. T. 1978. “The Orbits of the Satellites of Mars,” Vistas in Astronomy, 22, 133–140
Veverka, J., M. Noland, C. Sagan, J. Pollack et al. 1974. A Mariner 9 Atlas of the Moons of Mars, Icarus, vol. 23, Oct. 1974, p. 206–289
Woolard, Edgar W. 1944. “The secular Perturbations of the Satellites of Mars,” AJ, 51 (August, 1944), 33–36
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Dick, S.J. (2020). The Discovery and Exploration of the Moons of Mars. In: Space, Time, and Aliens. Springer, Cham. https://doi.org/10.1007/978-3-030-41614-0_34
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