Antoniadi Eugène M.

(b. Constantinople [now Istanbul], Turkey 1870); d. Meudon, France. 10 February 1944)

astronomy.

Born of a Greek family, Antoniadi was more than a professional astronomer; he was an astrophile. At the age of eighteen using very modest instruments, he began his long series of observations in Constantinople and on the island of Prinkipe. He published these observations and most of his others, in Camille Flammarion’s review L’astronomie, the bulletin of the Astronomical Society of France. A frequent and diligent observer, Antoniadi was also an artist. His drawings from observation far surpass those of many other astronomers who lacked his artistic ability.

In 1893 Antoniadi was Flammarion’s guest in his private observatory at Juvisy, near Paris. Here he was able to employ a forty-two-centimeter equatorial to observe Mars, which was his chief concern. As a result of his research he was appointed director of the section on Mars of the British Astronomical Association.

In 1909 H. Deslandres director of the observatory at Meudon, authorized him to make use of the large telescope there, which led Antoniadi to make important discoveries regarding the constitution of the surface details of Mars. This was possible because in that year the planet, in a close opposition, was in an extremely favorable position to be observed. Antoniadi’s excellent drawings of that particular opposition and of those that followed revealed that the strange network of geometrical “canals,” which some observers had thought to be man-made, are no more than an effect produced by very minute details. It was his conclusion that 70 percent of the canals are irregular dark bands more or less continuous and scattered with small spots that vary in width and appearance; 21 percent are irregular lines of gray, diffuse spots; 9 percent are isolated and complex nuclei. Antoniadi’s drawings, reproduced in his major work, show terrain covered with sparse vegetation, volcanic soil, and vast deserts.

During the opposition of 1924 Antoniadi observed, among other things, shining protuberances on the edge of the planet, precisely on the configuration called Hellas. The highest point of these protuberances seemed to oscillate, over a period of four days, eight to twenty kilometers above the surface of the planet. By observing the apparent motion of the various details of Mars, Antoniadi also was able to confirm the period of rotation about its axis, which had been determined by Giovanni Schiaparelli.

In later life Antoniadi became interested in the history of Greek and Egyptian astronomy; the results of his studies were published in L’astronomie and in his L’astronomie égyptienne. In addition, outside the field of astronomy, he conducted important archeological studies on the basilica of Saint Sophia in Constantinople, which were published in 1907. The French government awarded him the Cross of Chevalier of the Legion of Honor, and in 1928 he became a French citizen.

BIBLIOGRAPHY

Antoniadi’s major work is La planète Mars (Paris, 1930). Also see L’astronomie, 58 (1944), 58; and G. Abetti, Storia dell’astronomia (Florence, 1963). Antoniadi’s major contributions to periodicals are to be found primarily in the Bulletin de la Société astronomique de France and in the Journal of the British Astronomical Association.

Giorgio Abetti