Eugène Michel Antoniadi (1870 – February 10 1944) was a Turkish-born Greek astronomer who spent most of his life in France. He was also known as Eugenios Antoniadi. His name is also sometimes given as Eugène Michael Antoniadi or even incorrectly Eugène Marie Antoniadi.
He became a highly reputed observer of Mars, and at first supported the notion of Martian canals, but after using the 83-centimeter telescope at Meudon Observatory during the 1909 opposition of Mars, he came to the conclusion that canals were an optical illusion.
He also observed Venus and Mercury. He made the first attempts to draw a map of Mercury, but his maps were flawed by his incorrect assumption that Mercury had synchronous rotation with the Sun.
A crater on Mars and the Antoniadi crater on the Moon were named in his honor.
