Turkish-born French astronomer who demolished the theory of canals on Mars. He became an expert also on the scientific achievements of ancient civilizations. Antoniadi was born in Constantinople (now Istanbul). He began to make astronomical observations 1888, and in 1893 went to France to utilize better telescopes, first at the observatory at Juvisy-sur-Orge and then at Meudon. Detecting an apparent spot on the surface of Mars, he soon realized that it was merely an optical effect caused by the diffraction of light by the Earth's atmosphere.
There was at that time widespread belief that there was an intricate pattern of canals on the surface of Mars suggestive of advanced technology, as proposed 1877 by Italian astronomer Giovanni Schiaparelli.
Antoniadi suggested that the canals were also an optical illusion, produced by the eye's linking of many tiny surface details into an apparently meaningful pattern. Antoniadi's later work included research into the behaviour and properties of Mercury (published in La planète Mercure/The Planet Mercury 1934). He then turned to a study of the history of astronomy and, in particular, the work of the ancient Greek and Egyptian astronomers.