born in Turkey. He specialized in the planets, of which he was one of the most outstanding observers of his time. His highly detailed drawings show, for example, spots on Saturn’s disk and ‘spokes’ in its rings, the South Tropical Disturbance on Jupiter, and surface details on Mercury. Antoniadi’s chief interest, though, was Mars. He was sceptical about the Martian canals, and was able to demonstrate that they were illusory. He devised the Antoniadi scale for the quality of seeing.