Eugenios Mihail Andoniadis was one of the most famous of all planetary astronomers. Yet few Greeks anywhere in the world could readily identify this man. This is especially curious since E.M. Antoniadi (as he was later known) is the most renowned question of mapmaker of Mars in human history. It was not until the 1975 Viking orbiter images that Antoniadi’s maps became a part of history rather than regularly consulted geographic guides. Such was the level of Antoniadi’s overall work that he is attributed with finally resolving the most sensational and perplexing question ever to be raised by Mankind; the existence of the Martian canals.

On March 1, 1870, Antoniadi was born in the Tatavla quarter of Constantinople the son of Michel Antoniadi and Photini Alexiou. Antoniadi so quickly developed an interest in astronomy that by his late teens he was already systematically searching the night skies with a 3-inch (76-mm) refracting telescope. First in Constantinople and later on the beaches of the island of Prinkipo, the young Greek began to compile detailed drawings of the planets and other objects he observed. Antoniadi’s exceptional talent as a draftsman was immediately recognized as he submitted his drawings to the Societe Astronomique de France and the British Astronomical Association.

In 1893, the young Greek was invited by (Nicholas) Camille Flammarion (1842-1925), to work at his private observatory at Juvisy-sur-Orge, near Paris. Flammarion was one of the world’s leading astronomers as well as the funder, in 1887, of the French Astronomical Society. Antoniadi published regularly in this society’s official bulletin L’astronomie. While Antoniadi was to earn a reputation as a brilliant observer it is in his role as a publishing scholar upon which his international fame was to rest. Aside from French the young Greek was fluent in English and regularly wrote for the Journal of the British Astronomical Association. Once in France Antoniadi devoted the rest of his life to the telescopic observation of planetary surfaces.

Clearly Antoniadi was a well-respected colleague who was read and listened to closely. But he was not initially a leading figure at the very center of the field of cutting edge astronomical debate. All that would come with the international controversy over life on Mars.

Giovanni Virginio Schiaparelli (1835-1910), an Italian astronomer was the director of the Milan observatory from 1862 until, 1900, when he retired. Schiaparelli was the first to observe the asteroid Hesperia (1861) and is credited with identifying the orbits of numerous comets and shooting stars. Such was Schiaparelli’s work that he was awarded the prestigious Lalande Prize of the French Academie des Sciences in 1868. Today, Schiaparelli is most known for his observations and writings on the planet Mars.

Schiaparelli was not the first astronomer to draw maps of Mars but he was the first to note specific geographic features such as mountain ranges, seas, islands, capes, straits and so on. More importantly Schiaparelli was the first to systematically assign specific names to these geographic forms on his published maps. It was the translation of the word canali, which in Italian can mean either “channels” or “canals” that caused an international sensation.

Percival Lowell (1855-1916), a wealthy businessman and intellectual, who founded and became the director of the Lowell Astronomical Observatory in Flagstaff, Arizona, immediately, responded to the implications of canals on Mars. In 1906, Lowell published Mars and Its Canals arguing that for these massive canals to exist some intelligence must be at work on the planet surface (New York: Macmillan). A charismatic individual and dynamic public speaker Percival Lowell soon had the world scientific community and the world press abuzz with his theories.

Antoniadi made his observations from the Grand Lunette at Meudon to study Mars’s planetary oppositions between 1924 and 1941. While much of Antoniadi’ public life and work is documented his private life remains largely unknown. Curiously Antoniadi never officially belonged to the observatory staff. He referred to himself simply as the “astronome volontarie a l’Obervatoire de Meudon” Antoniadi was a man who could easily have secured a position in astromony literally anywhere in the world. But he did not seem to have needed such employment. On June 9, 1902, Antoniadi married Katherine Sevastupulo, who is said to have belonged to one of the leading families in Paris’s Greek community. Curiously history does not now record how Antoniadi made his living, assuming that he needed to do.

It is perhaps difficult for the modern Reader to fully comprehend the degree of public response and interest in Percival Lowell’s assertion of the intelligent life on Mars. What would otherwise have been dry academic articles read and argued by only a small circle of persons became the stuff of banner headlines in newspapers around the world. The scientific debate on the true surface of Mars became one of the very first international sensations of modern history.

At first, while at the Juvisy-sur-Orge observatory, Antoniadi was a supporter of Lowell’s work. Yet, Antoniadi’s own ongoing investigations and the publications of his colleagues caused him some considerable reflection. As William Sheehan has noted in, The Planet Mars: A History of Observation and Discovery, Antoniadi’s: “confidence in the whole network had been badly shaken by the “discovery” by Lowell and his assistants of what Antoniadi referred to as “subjective” linear markings on Mercury, Venus, and the Jovian satellites. Whereas in 1898 Antoniadi had stated that “despite the skepticism of several eminent authorities, I do not hesitate to say that the famous canals of Mars have a true objective existence,” by 1902 he characterized his position as “agnostic” (Tucson: University of Arizona Press, 1996).”

Such was Antoniadi’s professional accomplishments that no less a figure than Henri Deslandres (1853-1948) the director of the Meudon Observatory placed the Grand Lunette, then, as now the largest refractor telescope in Europe (and the third largest in the world) fully at the Greek’s disposal. This led to a revelation. As Antoniadi’s wrote of his observations of Martian deserts using the Grand Lunette, “[T]he soil of the planet then appeared covered with a vast number of dark knots and chequered fields, diversified with the faintest imaginable dusky areas, and marbled with irregular, undulating filaments, the representations of which was evidently beyond the powers of any artist. There was nothing geometrical in all this, nothing artificial, the whole appearance having something overwhelming natural about it.”

The ever-meticulous Antoniadi soon realized that various optical effects were at play. Some involved the diffraction of light by the Earth’s atmosphere that gave the illusion of spots on his telescope lens. Other’s had to do with the eye’s linking of many tiny surface details into apparently meaningful patterns. In time Antoniadi took the unwavering position that, “Nobody has ever seen a genuine canal on Mars.” He rightly concluded that the “completely illusory canals” seen on Mars were, in fact, irregular features on that planet’s surface. The entry on Antoniadi in the International Encyclopedia of Astronomy flatly concludes, “he settled the controversy about the canals on Mars (Patrick Moore, editor, New York: Orion Books, 1987).”

In 1930, Antoniadi published, La planete Mars, 1659-1929 (Paris: Hedrmann et Cie), which has been translated into English by Patrick Moore as The Planet Mars (Sheldon Devon, U.K.: Keith Reid, 1975). Much has been written about Antoniadi. For those interested in learning more about Antoniadi’s career they can consult Richard J. McKim’s, 1993, two part article, “The Life and Times of E.M. Antoniadi, 1870-1944. Part I: An Astronomer in the Making” (Journal of the British Astronomical Association 103: 164–170. Bibcode: 1993JBAA..103..164M and Bibcode: 1993JBAA..103..219M). A serviceable overview that has extended passages on Antoniadi’s career can be found in the William Sheehan book already mentioned.

Antoniadi has experienced lasting fame within the scientific community in yet another manner. No less than three geographic sites on two planets and one moon are named after him. On our Moon there is the Antoniadi Crater, on Mercury there is the Antoniadi Dorsum, and on Mars there is the 381 km Antoniadi Crater, so named in 1973. This means that quite literally in our solar system more geographic locations are named after Eugenios Mihail Andoniadis than any other single Greek in history. In like manner Modern Greek history will never be complete until figures such as Antoniadi, an internationally recognized astronomer, on an equal footing with figures such as Flammarion, Schiaparelli and Lowell are factored into the wider flow of historical events.