Édouard Stephan

Édouard Stephan, born on August thirty-first, eighteen thirty-seven, in Sainte Pezenne, France, was a distinguished astronomer whose contributions to the field are still recognized today. He graduated at the top of his class from the École Normale Supérieure in eighteen sixty-two, marking the beginning of a remarkable career in astronomy.

Stephan served as the director of the Marseille Observatory from eighteen sixty-four until nineteen oh seven, where he initially focused on enhancing the observatory's capabilities rather than conducting observations. His early work led to the discovery of the asteroid eighty-nine Julia in eighteen sixty-six, and he made significant strides in observational astronomy, including a notable transit of Mercury in eighteen sixty-seven.

Between eighteen seventy and eighteen seventy-five, he meticulously studied nebulae, documenting their positions and discovering numerous new ones. His innovative approach aimed to establish a reference system of fixed objects to facilitate the precise measurement of stellar proper motions. In eighteen seventy-three, he became the first to attempt measuring the angular diameter of a star using interferometry, although he did not succeed in resolving any stellar disks.

Stephan's discoveries include NGC five in eighteen eighty-one and the galaxy NGC six thousand twenty-seven the following year. He is perhaps best known for discovering Stephan's Quintet, a group of five galaxies, utilizing a telescope equipped with a reflection-coated mirror. His achievements earned him the Valz Prize from the French Academy of Sciences in eighteen eighty-four, and he was honored as a Chevalier of the Légion d'honneur in eighteen sixty-eight and later as an Officier in eighteen seventy-nine.